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A motor protection relay is a microprocessor-based protective device that continuously monitors the current, voltage, thermal state and sequence conditions of a medium-voltage induction or synchronous motor, and trips the associated circuit breaker or contactor when a fault or abnormal operating condition is detected. Selecting the right relay is not a catalogue exercise — it requires calculating the motor’s rated current, its thermal withstand behavior during starting, and the current-transformer ratios that feed the relay, then translating those numbers into correct protection settings. This guide walks through the method step by step, with a fully worked numeric example, and is relevant to engineers specifying pumping, compression, crushing and process-drive systems across the Middle East and Gulf (including Egypt and Saudi Arabia), North Africa, CIS and Sub-Saharan Africa markets, where MV motors above roughly 200 kW commonly move to dedicated numerical protection.

Why correct relay selection matters

An MV motor represents a large, expensive, often single-critical asset in a plant — a boiler feed pump, a compressor train, a conveyor drive. Two failure modes dominate the risk profile: thermal damage from prolonged overload or a stalled/locked rotor during starting, and electrical faults — phase, ground or internal winding faults — that must be cleared in milliseconds to limit iron and copper damage. An undersized or incorrectly set relay either nuisance-trips a healthy motor during normal starting (costing production) or fails to trip in time during a real fault (costing the motor itself, and potentially the upstream switchgear). Because motor starting current is many times the running current for a short but thermally significant period, motor protection relay setting is fundamentally a coordination problem between the motor’s thermal capability curve and the relay’s time-current characteristic — this is different from a simple feeder overcurrent relay.

The method: from nameplate data to relay setting

Step 1 — Determine the motor’s full-load current (FLC)

For a three-phase motor, the rated full-load current is derived from the nameplate rated power, voltage, power factor and efficiency:

I_FLA = P / (√3 × V × cosφ × η)

where P is rated shaft power in watts, V is rated line voltage, cosφ is rated power factor and η is rated efficiency. If the FLC is stamped on the nameplate, use that value directly — it already reflects the manufacturer’s design margins.

Step 2 — Establish the thermal withstand / starting characteristic

Every motor has a locked-rotor (starting) current, typically a multiple of FLC, and a maximum permissible locked-rotor time — the duration the stator and rotor windings can carry that starting current before insulation damage begins. This data (locked-rotor current multiple, hot/cold stall times) is supplied by the motor manufacturer and is the single most important input for setting the relay’s thermal overload and stall-protection curves — it must not be assumed generically.

Step 3 — Size the current transformers (CTs)

The relay measures current through dedicated protection-class CTs, not directly on the MV bus. CT primary rating should be chosen close to (and normally above) the motor FLC so the relay operates in a well-resolved part of its measuring range across the load range from light load to starting current, without saturating during the maximum through-fault current the CT must reproduce accurately.

Step 4 — Assign settings to each protection function

Once FLC, thermal/starting data and CT ratio are known, each protection element (thermal overload, locked rotor/stall, instantaneous and time overcurrent, earth fault, unbalance, differential if used) is set as a function of FLC or of the motor’s specific thermal curve — never as an arbitrary fixed current.

Worked example

Consider a 1000 kW, 11 kV MV induction motor with rated power factor cosφ = 0.87 and rated efficiency η = 0.95, driving a centrifugal pump.

Full-load current:

I_FLA = P / (√3 × V × cosφ × η) = 1,000,000 / (1.732 × 11,000 × 0.87 × 0.95) = 1,000,000 / (19,052 × 0.87 × 0.95) = 1,000,000 / 15,746 ≈ 63.5 A

Thermal overload setting (commonly applied practice is to set the relay’s thermal reference current between about 1.05 and 1.15 times FLC, to allow for measurement tolerance while still protecting the winding insulation):

I_set = 1.10 × 63.5 A ≈ 69.9 A

Illustrative locked-rotor / starting check: if the motor manufacturer states a locked-rotor current of 6 × FLC and a maximum hot stall time of, say, 12 seconds, the starting current would be:

I_LR = 6 × 63.5 A = 381 A

The relay’s stall/locked-rotor timer must then be set below the 12-second thermal withstand limit but above the motor’s normal accelerating time (for example, 8 seconds), so a healthy start is never blocked while a stalled rotor is still tripped before insulation damage occurs.

CT ratio selection: with an FLC of 63.5 A and an expected starting current of 381 A, a CT primary rated around 100 A (giving a secondary of 1 A or 5 A depending on relay input) keeps the motor operating comfortably within the CT’s linear accuracy range at both full load and starting current, while leaving margin below the CT’s rated accuracy limit factor for through-fault conditions.

Selection & setting comparison table

Selection criteria and common pitfalls

• Always use manufacturer motor data, not generic multipliers, for locked-rotor current and thermal withstand time — these vary significantly between motor designs and drive different relay curve selections.
• Match CT accuracy class to the protection function — a CT sized correctly for thermal/overload measurement may not have the accuracy-limit factor needed for a differential or high-set instantaneous element during a close-in fault.
• Coordinate the relay’s stall timer with actual starting time, especially for high-inertia loads (fans, crushers) where starting duration can approach the motor’s thermal withstand limit — a poorly coordinated relay will trip on every start.
• Account for restart and re-acceleration duty (e.g., after a brief supply dip) — successive-start counters and thermal memory functions prevent cumulative thermal damage from repeated starts.
• Differential protection (87M) is generally reserved for larger or critical motors, given the additional CT set required at both winding ends, while thermal, stall, overcurrent and earth-fault protection are considered standard on virtually all MV motor feeders.
• Verify relay and CT selection alongside the associated MV switchgear and protection relay panel design, and check upstream coordination with feeder and transformer protection so that a motor fault is cleared selectively without unnecessary upstream tripping.

Governing standards

Motor protection relay selection is guided by IEC 60255 (functional and performance requirements for measuring relays and protection equipment), IEC 60034-1 (rating and performance requirements for rotating electrical machines, the source of the motor’s nameplate parameters used in sizing), and IEEE C37.96 – Guide for AC Motor Protection, which specifically addresses the protection philosophy, function selection and coordination practices for AC induction and synchronous motors. Current transformers used to feed the relay are selected per IEC 61869-2, which defines protection accuracy classes and accuracy-limit factors relevant to CT sizing described above.

Related guides

See also our guides on medium voltage switchgear, gas-insulated switchgear and ring main units.

UniGear ZS1 metal clad switchgear is ABB’s mainline air-insulated medium-voltage switchgear platform, built for primary power distribution up to 24 kV with metal partitions segregating internal compartments and air-insulated live parts. This article covers the platform’s design, apparatus options, electrical ratings, applicable standards, and selection guidance for buyers in the Middle East and Gulf region including Egypt and Saudi Arabia, North Africa, CIS markets, and Sub-Saharan Africa, where UniGear ZS1 is widely specified for utility, industrial, and marine electrification projects.

What Is UniGear ZS1 Metal Clad Switchgear?

UniGear ZS1 is manufactured worldwide and forms part of ABB’s global distribution solutions portfolio, with a very large installed base and a manufacturing footprint spanning multiple continents. The switchgear has been installed in more than 100 countries, reflecting its status as a well-established global product line.

Each UniGear ZS1 panel is built as a single functional unit that can house a circuit-breaker, a contactor, or a switch-disconnector, along with the accessories typically expected in conventional switchgear units. A defining operational feature is that installation, operation, and maintenance are performed entirely from the front of the unit, with no rear access required — a practical advantage in installations built back-to-wall or in space-constrained rooms.

Panel Architecture and Compartmentation

Internally, each switchgear unit is divided into three power compartments — circuit-breaker, busbars, and cables — plus a separate low-voltage compartment that houses auxiliary instruments. These compartments are segregated from one another by metallic partitions, consistent with the platform’s Partition Metallic (PM) classification.

The main busbar system, made of copper with a flat cross-section, connects to the upper isolating contacts of the circuit-breaker through branch connections; higher-current variants use an open D-shaped busbar cross-section instead. Busbars and branch conductors rated at the higher voltage classes are insulated using shrink-on sleeves, and bolted connections are covered with insulating covers for additional protection. The cable compartment houses flat electrolytic-copper connections to the lower contacts of the circuit-breaker, and can be fitted with an earthing switch for cable earthing.

Arc-proof designs are typically equipped with a duct for evacuating gases generated by an internal arc event.

Types and Configuration Variants

UniGear ZS1 is offered in several busbar and space arrangements to match project layout and continuity requirements:

• Single busbar — the standard configuration, combinable with other units in the UniGear family.
• Double busbar system — for applications requiring source or bus redundancy.
• Back-to-back arrangement — for efficient use of switchroom floor area.
• Double-level design — a compact solution that stacks functional units to reduce footprint.
• A 500 mm wide panel option is also part of the ZS1 24 kV third-generation family, aimed at further reducing switchroom width.

On the apparatus side, ABB offers what is described as one of the most complete ranges on the market for this platform:

• Withdrawable vacuum circuit-breakers with mechanical or magnetic actuator.
• Withdrawable gas (SF6) circuit-breakers.
• Withdrawable vacuum contactors with fuses (ConVac).
• Fixed switch-disconnector units.

This shared apparatus platform allows the same switchgear-user interface and the same operating and maintenance procedures across a project regardless of which apparatus type is fitted. Additional design features include protection and control units, standard and ultra-fast earthing switches, IS-limiter fault-current limitation devices, integrated capacitor banks, and bay control and protection units.

Electrical Characteristics

The table below summarizes the rated electrical characteristics across the UniGear ZS1 voltage classes.

Circuit-breaker rated current steps offered across the range include 630 A, 1250 A, 1600 A, 2000 A, 2500 A, and 3150 A, with forced-ventilation variants extending up to 3600 A and 4000 A on the lower voltage classes. Panels equipped with a contactor are rated at 400 A. A GB/DL variant is available with enhanced dielectric performance up to 42 kV and extended short-time withstand duration. A CSA-compliant version is available up to 27.6 kV.

LSC and Partition Classification (IEC 62271-200)

Under IEC 62271-200, switchgear is classified by Loss of Service Continuity (LSC) and partition type rather than by the older metal-enclosed/compartmented/cubicle categories. The most common UniGear ZS1 panel classification is LSC2B, PM — meaning the cable compartment, adjacent functional units, and main busbars can remain energized while a main-circuit compartment on one unit is opened for maintenance, with metallic partitions (PM) separating live compartments.

Front access to high-voltage compartments is interlock-controlled, while rear-side compartments (not intended for normal operation) are tool-based access only, requiring special procedures. Depending on panel type — incoming/outgoing, bus-tie, riser, measurement, contactor, or switch-disconnector units — the assigned LSC category ranges from LSC1 to LSC2B across the different rated-current and short-circuit variants.

Safety and Internal Arc Performance

UniGear ZS1 functional units are guaranteed arc-proof in accordance with IEC 62271-200, Appendix AA, class A accessibility criteria 1 to 5. The switchgear carries the internal arc classification IAC AFLR, and both the switchgear and its earthing switches are operated from the front with the door closed. When specifying arc-fault protection for a project, fault current levels of 16 to 63 kA and fault durations of 0.1 to 1 second must be considered, along with gas-evacuation escape routes and room dimensions.

Standard ingress protection is IP4X for the outer enclosure and IP2X for internal compartment partitions, with higher degrees of protection available on request. Circuit-breaker racking is performed with the door closed, and other safety interlocks are built into the design.

Environmental and Site Conditions

Rated characteristics are guaranteed within an ambient temperature range of −5 °C to +40 °C. Humidity limits are specified as a maximum 24-hour average relative humidity of 95% RH and a maximum monthly average of 90% RH, with corresponding water vapour pressure limits of 2.2 kPa (24h) and 1.8 kPa (monthly). Normal operating altitude is up to 1000 metres above sea level, with higher altitudes requiring consultation with ABB.<!– 🔴 idd

Related guides

See also our guides on gas-insulated switchgear, ring main units and air-insulated switchgear.

The Relion series is ABB’s family of numerical protection, control, measurement and supervision relays for medium-voltage feeders, in which REF601, REX615 and REX640 represent entry-level, standard, and advanced feeder-protection relay classes built around IEC 61850-based substation communication. This article explains how the three relay classes differ, what protection and control functions a typical feeder relay in this family provides, how to select between them, and where they fit into MV switchgear projects across the Middle East and Gulf region (including Egypt and Saudi Arabia), North Africa, the CIS, and Sub-Saharan Africa.

What Is a Relion Series Protection Relay?

A Relion-series relay is a microprocessor-based intelligent electronic device (IED) that combines overcurrent, earth-fault, and related protection functions with control, measurement, disturbance recording, and communication capabilities for a single MV feeder bay or busbar section. Within the family, REF601 is positioned as a compact, cost-optimized feeder protection unit; REX615 is a re-engineered, standard-configuration feeder protection relay guided by the IEC 61850 standard for communication and interoperability of substation automation devices ; and REX640 sits at the higher end of the platform, aimed at applications needing extended functionality and flexibility. Because ABB’s own product documentation for this generation of feeder relays is published under the REF615 designation, the technical detail below is grounded in that document and should be read as representative of the 615-class relay within the Relion family; REF601 and REX640 features are described qualitatively where source-verified figures are not available.

Relion Relay Classes at a Glance

REF601 — a basic-tier feeder protection relay intended for simpler distribution feeder applications where a compact footprint and core overcurrent/earth-fault protection are the priority. Detailed numeric ratings for REF601 are not covered in the source document referenced here and should be confirmed against the specific REF601 datasheet before specification.

REX615 — the standard-configuration feeder protection relay described in ABB’s REF615 product guide. It is designed for protection, measurement and supervision of utility substations and industrial power systems, providing main protection for overhead line and cable feeders in distribution networks, and back-up protection where an independent, redundant protection system is required . It supports isolated neutral, resistance earthed, compensated and solidly earthed network types depending on the configuration selected .

REX640 — positioned as a more advanced feeder/bay-level relay in the same platform generation, intended for applications requiring greater functional depth and flexibility than the standard 615-class relay; specific numeric ratings for REX640 are outside the scope of the source document used for this article and should be verified directly with ABB technical documentation.

Standard Configurations and Protection Functions (REX615 Reference)

The REX615-class relay is available in four alternative standard configurations, labelled A, B, C and D, which combine directional or non-directional earth-fault protection with a common core of overcurrent and supervisory functions . Configurations A and B include directional earth-fault protection, intended mainly for isolated or compensated networks, while configurations C and D provide non-directional earth-fault protection for directly or low-impedance earthed networks .

Across all four standard configurations, the relay includes:

• Three-phase non-directional overcurrent protection with low-set, two high-set instances, and an instantaneous stage
• Negative-sequence overcurrent protection (two instances), phase discontinuity protection, and thermal overload protection
• Circuit-breaker failure protection and three-phase inrush current detection
• Optional arc protection using up to three light-detection sensors for switchgear compartments

Configurations A and B additionally provide directional and non-directional earth-fault low/high-set stages, cross-country earth-fault detection, and transient/intermittent earth-fault protection, while configurations C and D add non-directional sensitive earth-fault protection .

Control, Measurement and Recording Capabilities

The relay provides control of one circuit breaker via dedicated push-buttons, with interlocking schemes configured through the signal matrix tool in the engineering software . Two interlocking modes are available: basic interlocking, where circuit-breaker closing is enabled through a binary input acting as a master interlocking signal, and extended interlocking, where the interlocking scheme is implemented inside the relay configuration based on primary-equipment position information .

Measurement functions continuously track phase currents, symmetrical current components, residual current, and — where directional earth-fault protection is fitted — residual voltage, together with maximum demand, thermal overload level, and phase unbalance .

The disturbance recorder captures up to 12 analog and 64 binary signal channels, with recordings triggerable by threshold crossing or by rising/falling binary-signal edges . The event log stores up to 50 time-stamped event codes in non-volatile memory , and the relay retains records for the four most recent fault events, including current/voltage values and start-time stamps, using DFT, RMS or peak-to-peak measurement modes .

Circuit-breaker condition monitoring covers spring charging time, SF6 gas pressure, travel time and inactivity time, supporting preventive maintenance scheduling , while trip-circuit supervision continuously checks trip-circuit availability in both open and closed breaker positions and detects loss of control voltage .

Inputs, Outputs and Communication

Access to the relay is protected by a four-level, role-based authentication system covering viewer, operator, engineer and administrator roles, applied consistently across the front-panel HMI, web-browser interface, and engineering tool . A built-in self-supervision system continuously checks relay hardware and software integrity and will block protection functions on detection of a permanent fault, to prevent incorrect operation .

Selection Criteria: Choosing Between REF601, REX615 and REX640

When specifying a Relion-family feeder relay for an MV project, buyers should weigh:

• Network earthing type — directional earth-fault protection suits isolated or compensated networks, while non-directional earth-fault protection fits directly or low-impedance earthed systems .
• Functional depth required — REF601 for compact, cost-sensitive feeder applications; REX615 for standard utility/industrial feeder protection with configurable directional/non-directional schemes; REX640 where extended functionality beyond the standard configuration set is needed.
• Arc-flash protection needs — if fast, sensor-based arc-fault tripping is required for switchgear compartments, confirm the optional arc-protection interface is available on the chosen relay and communication module .
• Circuit-breaker interlocking complexity — simple master-interlock schemes can use basic interlocking; multi-bay or busbar-protection-by-interlocking schemes typically need extended interlocking logic within the relay.
• Communication architecture — verify IEC 61850/GOOSE and Modbus support align with the substation automation system already deployed or planned.
• Recording and diagnostics depth — projects needing detailed post-fault analysis benefit from the multi-channel disturbance recorder, event log and fault-record storage described above.

Sound practice standards and compliance for this relay class rest on adherence to IEC 61850-based communication and interoperability principles, alongside the manufacturer’s own type-test documentation; no switchgear-specific IEC 62271 series requirements apply to relay selection itself, since protection relays are secondary equipment rather than primary switchgear.

Applications

Relion-series feeder relays are applied across:

• Utility distribution substations protecting overhead line and cable feeders
• Industrial power systems requiring independent, redundant back-up protection
• Incoming and outgoing feeder bays in metal-enclosed switchgear, including busbar protection by interlocking between incoming and outgoing feeder relays
• Retrofits and new-build MV substations across the Middle East and Gulf region (including Egypt and Saudi Arabia), North Africa, the CIS, and Sub-Saharan Africa, where robust feeder protection and IEC 61850-based communication support utility and industrial modernization programs.

Related guides

See also our guides on medium voltage switchgear, gas-insulated switchgear and ring main units.

8DJH gas insulated switchgear is a factory-assembled, type-tested, three-pole, metal-enclosed single-busbar medium-voltage switchgear from Siemens, designed for indoor secondary distribution systems and insulated with SF6 gas inside hermetically sealed, welded stainless-steel vessels. This article explains the 8DJH product family — its panel types, electrical ratings, construction, applications, and governing standards — so procurement and engineering teams can specify the correct configuration for a given project. Buyers across the Middle East and Gulf region including Egypt and Saudi Arabia, North Africa, the CIS states, and Sub-Saharan Africa evaluate 8DJH switchgear specifically for its compact footprint, environmental sealing, and minimal maintenance burden in harsh or space-constrained substations.

What Is 8DJH Gas Insulated Switchgear?

8DJH is Siemens’ gas-insulated medium-voltage switchgear platform for secondary distribution systems, built around a single busbar architecture. The primary circuit — busbars, switching devices, and cable terminations — is housed inside welded stainless-steel vessels filled with SF6 insulating gas, which is described as non-toxic, odorless, colorless, non-inflammable, chemically neutral, heavier than air, and electronegative (a high-quality insulator). This gas has a Global Warming Potential (GWP) of 22,800.

Because the primary circuit is hermetically sealed against the environment, 8DJH switchgear is positioned as insensitive to aggressive ambient conditions such as saline air, humidity, dust, and condensation, and tight against ingress of dust, pollution, small animals, and moisture. This makes it a preferred choice for coastal, desert, and industrial installations where air-insulated equipment would face accelerated degradation.

Panel Types and Variants

Siemens offers 8DJH in several configurations to match substation layout and functional requirements:

• Individual circuit-breaker panel (500 mm) — a single-function panel equipped with a vacuum circuit-breaker and three-position disconnector for protection duties.
• 8DJH Standard panel blocks — modular ring-main and transformer feeder combinations for typical secondary substations.
• 8DJH Compact — a reduced-footprint variant intended for space-constrained rooms and prefabricated substations, including designs suitable for installation without a control aisle.
• RRT block — a combined ring-main/transformer feeder block used in common distribution layouts.
• Air-insulated billing metering panels — used alongside the gas-insulated panels where separate air-insulated metering compartments are required.

Panels and panel blocks can be lined up and extended on site without any SF6 gas work, and the low-voltage compartment is available in multiple overall heights with plug-in wiring to simplify commissioning and future extension.

Electrical Ratings and Technical Data

The table below summarizes the maximum electrical values published for 8DJH across its available rated-voltage classes.

Panel width depends on feeder function, with options of 310 mm, 430 mm, or 500 mm. Panel depth is 775 mm without the pressure relief duct and 890 mm with it. Panel height, excluding the low-voltage compartment and pressure relief duct, is available in 1040 mm, 1200 mm, 1400 mm, or 1700 mm options.

SF6 Gas System Parameters

The switchgear vessel is filled with SF6 gas at a rated filling level of 150 kPa (absolute, at 20 °C) with a design pressure of 180 kPa and a design gas temperature of 80 °C. The bursting disc operates at a pressure of at least 300 kPa, with bursting pressure of at least 550 kPa. The system is designed for a gas leakage rate below 0.1% per year, supporting the sealed-for-life claim.

Vacuum Circuit-Breaker and Switching Devices

Protection feeders use a vacuum circuit-breaker combined with a three-position disconnector for disconnecting and earthing functions. The circuit-breaker is maintenance-free under normal ambient conditions, requires no relubrication or readjustment, is rated for up to 10,000 operating cycles, and is vacuum-tight for life. Ring-main and switching functions are served by the three-position switch-disconnector, which provides load-break switching plus make-proof earthing.

Selection Criteria

When specifying 8DJH gas insulated switchgear, buyers should evaluate:

• Rated voltage class — select from the 7.2 kV, 12 kV, 15 kV, 17.5 kV, or 24 kV classes based on network voltage and required insulation margin.
• Short-circuit withstand requirement — match the network’s prospective fault level against the rated peak, making, and short-time withstand current figures for the chosen voltage class.
• Feeder mix — ring-main, circuit-breaker, and transformer feeders each have different rated normal current allocations (200 A / 250 A / 400 A / 630 A depending on function and design options).
• Panel type — Standard, Compact, RRT block, or individual circuit-breaker panel depending on footprint and layout constraints.
• Internal arc classification (IAC) needs — where personnel safety in the event of an internal fault is a priority, verify the IAC option and its test parameters.
• Installation arrangement — wall-standing or free-standing, and whether pressure relief is directed downward, to the rear, or upward.
• Regional approvals — for CIS markets, confirm GOST R certification applicability.

Applications

8DJH switchgear is used at the secondary distribution level in public and industrial energy systems, including local ring-main units, customer transfer substations, and switching substations of power supply and public utilities; wind power, solar, and hydroelectric plants; water and sewage treatment plants; airports, railway stations, and underground railway stations; open-cast mining facilities; and high-rise buildings.

Safety, Personnel Protection, and Service Life

All high-voltage parts of the primary circuit carry a standard degree of protection of IP65, and the overall switchgear enclosure provides at least IP2X, per IEC 60529 and VDE 0470-1. Feeder earthing is achieved through make-proof earthing switches, and HV HRC fuses and cable sealing ends are accessible only when outgoing feeders are earthed, reducing the risk of contact with live parts during maintenance.

Where the optional internal arc classification is specified, 8DJH panels are tested for resistance to internal faults with an arc test current of up to 21 kA for a test duration of 1 second. The IAC designation covers accessibility types — front (F), lateral (L), and rear (R) — for wall-standing and free-standing arrangements, and the Compact design also supports use in prefabricated substations without a control aisle, tested to IEC 62271-202.

Under normal operating conditions, the expected service life of 8DJH gas-insulated switchgear is at least 35 years, and probably 40 to 50 years, taking the tightness of the hermetically welded switchgear vessel into account. Service life limitations are governed by the operating-cycle endurance classes of the installed switching devices: circuit-breakers per the endurance class in IEC 62271-100, three-position disconnectors and earthing switches per IEC 62271-102, and three-position switch-disconnectors and earthing switches per IEC 62271-103.

Siemens states that more than 500,000 switchgear panels of this type of design are in operation worldwide, supporting a track record of field reliability.

Standards and Regional Approvals

8DJH switchgear is classified according to IEC/EN 62271-200 / VDE 0671-200. The sealed-for-life design (sealed pressure system) also follows IEC 62271-200. General maintenance-free operation under normal ambient conditions is referenced to IEC 62271-1 and VDE 0671-1. Interlocking systems comply with IEC 62271-200 and VDE 0671-200. Cable connections use the outside-cone plug-in system per DIN EN 50181. Metal partitioning corresponds to the “metal-clad” concept per the former standard IEC 60298.

The manufacturing system is certified according to ISO 9001, ISO 14001, and BS OHSAS 18001, with quality assurance additionally referenced to DIN EN ISO 9001.

For CIS-region projects, 8DJH holds national GOST R certification in Russia, approved for application at voltage levels of 6 kV, 10 kV, and 20 kV, with validity extending to Russia, Belarus, Kazakhstan, and Ukraine.<!– 🔴 iddia: By certification in the system GOST R in Russia, 8DJH is approved for application at the voltage levels 6 kV, 10 kV and 20 kV. The

Related guides

See also our guides on ring main units, metal-clad switchgear and air-insulated switchgear.

NXPLUS switchgear is Siemens’ factory-assembled, type-tested, metal-enclosed, SF₆-insulated medium-voltage circuit-breaker switchgear line, offered as NXPLUS C for fixed-mounted, single- and double-busbar indoor applications up to 36 kV. This article explains the NXPLUS C product family, its construction principles, its published electrical ratings, typical industrial and utility applications, and the governing IEC/IEEE/CSA standards, for buyers sourcing gas-insulated MV switchgear across the Middle East and Gulf region (including Egypt and Saudi Arabia), North Africa, CIS countries, and Sub-Saharan Africa.

What Is NXPLUS Switchgear?

NXPLUS C is a hermetically sealed, gas-insulated switchgear system built around welded stainless-steel switchgear vessels that keep the busbars, cable terminations, and instrument transformers isolated from ambient air and mechanical damage. Because the primary circuit is protected inside a sealed SF₆ vessel, the design is described by Siemens as maintenance-free under normal indoor service conditions in accordance with IEC 62271-1. The switchgear vessel and the sealed pressure system are also designed to comply with the sealed-for-life provisions of IEC 62271-200.

The switchgear uses a three-position switch functioning simultaneously as busbar disconnector and feeder earthing switch, combined with a vacuum circuit-breaker that provides make-proof earthing capability. This arrangement, together with logical mechanical interlocking, is intended to prevent maloperation sequences such as closing an earthing switch onto a live busbar.

Types and Panel Variants

NXPLUS C is delivered as fixed-mounted circuit-breaker panels rather than withdrawable truck-type breakers, which simplifies the enclosure design while still allowing panel replacement without SF₆ gas work. The catalog structure covers:

• Single-busbar panels — the standard configuration for most substation and industrial feeder applications.
• Double-busbar panels — used where source/feeder transfer flexibility or n-1 busbar redundancy is required.
• Circuit-breaker panels in multiple widths — available in 450 mm, 600 mm, and 900 mm variants shown in the catalog, in addition to a 300 mm option.
• Air-insulated metering panel — used for block-type current and voltage transformers where dielectric stress considerations differ from the gas-insulated primary panels.
• Auxiliary transformer panel — houses a three-phase or single-phase dry-type transformer rated at 40 kVA or 10 kVA, with Dyn1, Dyn5, or Li0 connection symbols.

Both single- and double-busbar panel families are covered by dedicated panel-dimension and electrical-data sections in the manufacturer catalog, allowing engineers to align panel selection with substation layout and busbar architecture.

Selection Criteria for Buyers

When specifying NXPLUS-type gas-insulated switchgear, procurement and engineering teams typically evaluate the following criteria:

1. Rated voltage class. NXPLUS C covers a rated voltage range from 7.2 kV up to 36 kV, with an additional 38 kV rating listed for certain national requirements. Select the voltage class matching the incoming or distribution network level.

2. Short-circuit performance. Rated short-time withstand current and rated short-circuit breaking current values differ across the voltage range — buyers should match panel short-circuit ratings to prospective fault levels at the installation point, not just to nominal voltage.

3. Continuous current requirements. Busbar and feeder continuous-current ratings must be checked against expected load and future load growth, since feeder current ratings can differ from busbar current ratings at the higher end of the voltage range.

4. Enclosure protection and site environment. The standard degree of protection is IP65 for the high-voltage primary parts and IP3XD for the switchgear enclosure according to IEC 60529. This is relevant for sites with saline air, dust, humidity, or condensation risk, such as coastal, offshore, or desert installations.

5. Internal arc classification. Panels are tested for resistance to internal faults up to 31.5 kA, an important criterion for personnel safety compliance in enclosed switchrooms.

6. Circuit-breaker duty cycle. The vacuum circuit-breaker is rated for up to 10,000 operating cycles as standard, with an option extending this to up to 30,000 operating cycles for higher-duty applications.

7. Expected service life. Under normal service conditions the expected service life of the gas-insulated switchgear is at least 35 years, and potentially 40 to 50 years, limited mainly by the maximum number of switching-device operating cycles.

8. Environmental compliance. SF₆ has a documented Global Warming Potential of 24,300 according to IPCC AR6 GWP100 methodology, a figure buyers should weigh in sustainability procurement policies.

9. Standards and certification requirements. For projects requiring North American compliance, NXPLUS C switchgear conforms to IEEE STD C37.20.9 and is certified to CSA STD C22.2 No. 31, in addition to marine/offshore type approvals.

Electrical Ratings Table

The table below summarizes representative maximum electrical ratings across the NXPLUS C voltage range, as published in the manufacturer catalog.

The full catalog also lists intermediate voltage classes (15 kV, 17.5 kV, and 38 kV) with corresponding withstand and current values, and notes alternate national ratings of 32 kV/60 kV and 42 kV/75 kV for some markets.

Construction and Personnel Safety Features

NXPLUS C keeps all high-voltage parts — cable terminations, busbars, and voltage transformers — inside earthed, metal-enclosed compartments, which corresponds to the “metal-clad” classification under the former IEC 60298 standard. A capacitive voltage detecting system allows operators to verify safe isolation from supply before accessing compartments, and operating mechanisms plus auxiliary switches remain accessible from outside the sealed primary enclosure, so routine operation never requires opening the gas-filled vessel.

Instrument transformers are designed to minimize dielectric stress on current transformers, which are of the ring-core type and mounted outside the SF₆ vessel for straightforward replacement, while voltage transformers are metal-coated and plug-in for easy disconnection during maintenance work elsewhere in the panel.

Interlocking follows IEC 62271-200 principles: the three-position disconnector/earthing switch cannot select the READY-TO-EARTH function while in the DISCONNECTING position and vice versa, and the circuit-breaker can only be operated with the disconnector in its defined end position and the operating lever removed. Padlock-based locking options give additional operational control over which switching function is available at any given time.

Siemens reports that more than 500,000 switchgear panels of this general design family are in operation worldwide, supporting the long service-life expectation for the product line.

Digitalization and Condition Monitoring

NXPLUS C can be integrated with Siemens Xcelerator, an open digital platform aimed at grid stability management, cyber and asset security, CAPEX/OPEX optimization, and distributed energy resource integration. Condition monitoring functionality is positioned to extend the resilience and availability of the maintenance-free, gas-insulated switchgear over its expected multi-decade service life, referencing the design and empirical data basis defined under IEC 62271-1.

Secondary systems can include customary protection, measuring, and control equipment, or an optional numerical multifunction protection relay combining protection, control, communication, operating, and monitoring functions integrable into process control systems. Current and voltage sensing can also be implemented via inductive current transformers with precision shunts and resistor-divider voltage sensors, used in combination with devices such as SICAM FCM or 7SJ81 relays.

Applications

NXPLUS C fixed-mounted circuit-breaker switchgear is applied across a broad range of transformer and switching substations, including power supply companies, power stations, cement plants, automobile manufacturing, iron and steel works, rolling mills, mining operations, textile/paper/food processing, chemical and petroleum industries, pipeline installations, offshore platforms, electrochemical and petrochemical plants, shipbuilding, diesel and emergency power supply installations, lignite open-cast mines, and traction power supply systems.

The switchgear has also received type approval from classification societies DNV GL and the American Bureau of Shipping (ABS), making it suitable for marine and offshore platform applications where recognized class certification is a procurement requirement. This combination of industrial versatility and marine certification makes NXPLUS-type gas-insulated switchgear a relevant specification option for buyers across the Middle East and Gulf region (including Egypt and Saudi Arabia), North Africa, CIS countries, and Sub-Saharan Africa, where projects frequently span onshore industrial plants, offshore oil and gas platforms, and utility distribution networks with challenging ambient conditions.

Standards and Certifications

NXPLUS C switchgear design and testing references multiple IEC provisions relevant to gas-insulated MV switchgear:

• IEC 62271-1 — general requirements for high-voltage switchgear and controlgear, referenced for maintenance-free operation under normal service conditions.
• IEC 62271-200 — metal-enclosed switchgear standard, referenced for interlocking requirements and the sealed pressure system/sealed-for-life design.<!– 🔴 iddia: interlocks according to IEC 62271-200 and sealed pressure system design per IEC 62271-200 — kaynak Siemens NXPLUS Type MEDIUM-VOLTAGE SWITCHGEAR Fixed-Mounted Circuit-Bre

Related guides

See also our guides on ring main units, metal-clad switchgear and air-insulated switchgear.

NXAIR switchgear is Siemens’ air-insulated, metal-enclosed, factory-assembled medium-voltage switchgear platform designed for primary distribution applications up to 17.5 kV and up to 40 kA short-circuit rating. This article covers the NXAIR design and classification, its main components, technical characteristics, typical applications, and the governing IEC standard, giving procurement and engineering teams the information needed to specify the product correctly. NXAIR is widely deployed by utilities and industrial end users across the Middle East and Gulf region (including Egypt and Saudi Arabia), North Africa, the CIS, and Sub-Saharan Africa, where robust air-insulated switchgear is preferred for primary substations, industrial plants, and offshore installations.

What Is NXAIR Switchgear?

NXAIR is a global platform of circuit-breaker switchgear that uses ordinary air as the insulating medium instead of SF6 or other F-gases, combined with maintenance-free vacuum interrupters for switching duty. Because air is the insulation medium, no gas handling, gas monitoring, or pressure supervision is required on site, simplifying installation and long-term operation. The platform concept means the same design principles are applied worldwide, with centrally controlled development and locally manufactured components adapted to regional standards. More than 610,000 air-insulated Siemens switchgear panels of this family are reported in operation worldwide, reflecting a long track record in the field.

Design and Classification

NXAIR is factory-assembled, metal-enclosed, and type-tested switchgear for indoor installation, classified according to IEC 62271-200. The switchgear is built around a modular panel with distinct compartments — busbar, switching-device, connection, low-voltage, and a withdrawable circuit-breaker section — each separated by pressure-resistant partitions for enhanced operator safety.

Key classification parameters include:

• Loss of service continuity category: LSC 2B, meaning the busbar, connection, and switching-device compartments are separately partitioned.
• Partition class: PM, i.e., metal-clad in pressure-resistant design.
• Internal arc classification: IAC A FLR, covering front, lateral, and rear accessibility, valid for all rated short-circuit currents with an arc duration of 1 second.
• Degree of protection: Standard IP3XD, with higher degrees of protection available as an option, up to a maximum of IP51.
• Internal arc confinement: The switchgear confines an internal arc to the respective compartment for short-circuit currents up to 31.5 kA.

All high-voltage operations require the door to be closed and interlocked, and the design incorporates earthed shutters, a logical mechanical interlocking system, and unambiguous position indicators on the high-voltage door for safe, error-free operation.

Main Components

The NXAIR panel integrates several key components:

• Vacuum circuit-breaker — withdrawable, maintenance-free switching device using Siemens’ SION circuit-breaker series, contributing to the compact panel footprint.
• Switch-disconnector/fuse combination and vacuum contactor options for feeder protection variants.
• Block-type current transformers — standardized units used across the platform.
• Voltage transformers, including a withdrawable option.
• Make-proof earthing switch, type-tested together with the main switching devices in the panel.
• Low-voltage compartment — removable, with plug-in wiring for flexibility.
• Optical arc detection systems and the SIQuench arc quenching device, available to further reduce the consequences of an internal arc event.
• Pressure relief duct system for directing arc energy safely away from the operator area.

Cable testing can be performed without isolating the busbar, and functions such as isolating-distance establishment and feeder/busbar earthing can be fully controlled remotely, supporting safer and faster switching operations.

Technical Data Summary

Applications

NXAIR circuit-breaker switchgear is deployed at transformer and switching substations, primarily at the primary distribution level. Typical sectors include public power supply — power supply companies, energy producers, and system operators — as well as a broad range of industrial and offshore applications such as the automobile industry, traction power supply, mining, chemical processing, diesel power plants, electrochemical plants, emergency power installations, textiles, paper and food processing, iron and steel works, oil and gas, offshore platforms, petrochemical plants, pipeline installations, data centers, shipbuilding, cement production, and rolling mills.

NXAIR has also been type-approved for maritime and offshore use by classification societies Lloyd’s Register and DNV, confirming its suitability for shipboard and platform installations.

Standards, Sustainability, and Certification

NXAIR switchgear is manufactured and sold under a certified management system in accordance with ISO 9001, ISO 14001, and BS OHSAS 18001. Classification and type testing follow IEC 62271-200 for metal-enclosed, indoor switchgear.

From a sustainability standpoint, NXAIR relies on natural air as its insulating medium and vacuum interrupters for switching, and it is free of asbestos, mercury, SF6, and other F-gases. Siemens performs Life Cycle Assessments and provides Environmental Product Declarations for reference installations, following the ISO 14040/14044 series of standards. The maintenance-free vacuum circuit-breakers, homogeneous and fully recyclable materials, and a service life beyond 30 years contribute to a favorable lifecycle energy balance for owners.

Related guides

See also our guides on gas-insulated switchgear, ring main units and metal-clad switchgear.

The Easypact EXE medium voltage breaker is a range of vacuum circuit breakers from Schneider Electric’s Easy series, engineered to combine mechanical simplicity with digital-ready condition monitoring for medium-voltage switchgear. This article covers the breaker’s design, its main electrical ratings under IEC 62271-100:2012, digital/thermal-monitoring capabilities, selection criteria, and typical applications for panel builders and end users. Buyers across the Middle East and Gulf region (including Egypt and Saudi Arabia), North Africa, CIS, and Sub-Saharan Africa evaluate the EasyPact EXE for substation, industrial, and commercial retrofit and greenfield projects where fast delivery and simplified customization matter.

What Is the EasyPact EXE Circuit Breaker?

EasyPact EXE is positioned by Schneider Electric as a best-in-class vacuum circuit breaker solution for electrical rooms in commercial buildings, industrial plants, and power grid substations. The design draws on Schneider Electric’s long-standing experience in the electrical industry, targeting greater simplicity, flexibility, and peace of mind for both panel builders and switchgear operators.

Three value pillars define the product proposition:

• Shortened project delivery time — simple online selection, quotation and ordering, plus fast, simple customization supported by Schneider’s expert team.
• Customization flexibility — modular kits covering a wide choice of configurations, including thermal monitoring, and readiness for EcoStruxure digital solutions and services.
• Peace of mind — remote racking option, simplified fire-prevention provisions, and a secured integration process supported by Schneider’s technical team.

EasyPact EXE Fixed Circuit Breaker — Design Overview

The EasyPact EXE fixed-version circuit breaker uses drilled and threaded copper connection terminals at the top and bottom of the unit. The exact shape and dimensions of the connecting conductors must be defined by the panel builder, based on the dielectric withstand and temperature-rise requirements of the complete connection system in the switchgear cubicle.

Depending on the switchgear architecture, field deflectors may be needed on the connection terminals to reach the breaker’s rated lightning impulse withstand voltage of 95 kV. This detail is important for engineers specifying insulation coordination at the panel level, since terminal geometry — not just the breaker rating — influences the achievable impulse withstand performance in the installed assembly.

Technical Specification (IEC 62271-100:2012)

The main electrical characteristics of the EasyPact EXE fixed circuit breaker are defined according to IEC 62271-100:2012.

For projects requiring a higher rated power-frequency withstand voltage at 42 kV for 5 minutes, this configuration is available on request directly from Schneider Electric. Additional characteristics beyond this core table are also defined under IEC 62271-100, and are addressed in the manufacturer’s common characteristics documentation for the range.

This spread of ratings — two voltage classes, three short-circuit breaking currents, and six normal current steps — gives specifiers a fairly broad matrix to align the breaker with substation, industrial feeder, or commercial building distribution requirements without over-specifying the switchgear bay.

Digital and Connected Features

A distinguishing element of the EasyPact EXE compared with a conventional vacuum breaker is its readiness for condition-based maintenance through Schneider Electric’s EcoStruxure Power architecture.

TH110 thermal sensor — a battery-less sensor integrated in the equipment that provides continuous thermal monitoring of critical field connections, helping to prevent unscheduled downtime and improve operator and equipment safety as part of a predictive maintenance strategy. The sensor covers connections such as circuit breaker arms, cable connections, and busbar connections.

Easergy Thermal Connect — a mobile app that gives technicians on-demand access to thermal monitoring data. Local connectivity allows nearby thermal monitoring on a smartphone from a distance of up to 10 m from the switchgear, with data access via QR code or NFC tag.

Digital Logbook and QR code access — each unit’s QR code unlocks a library of apps and services, including a paperless Digital Logbook for storing and sharing project documentation such as user manuals, single-line drawings, factory and site acceptance test records, and spare parts lists throughout the asset’s life cycle.

EcoStruxure Power platform — the breaker’s digital ecosystem sits within Schneider Electric’s open, interoperable IoT platform, spanning Connected Products, Edge Control, and Apps/Analytics/Services layers, supported by end-to-end cybersecurity.

Selection Criteria for the EasyPact EXE Breaker

When specifying an EasyPact EXE breaker for a medium-voltage switchgear panel, engineers should evaluate:

1. System voltage class — match the panel’s rated voltage to the breaker’s rated voltage options.
2. Fault-current withstand — select a rated short-circuit breaking current with adequate margin above the calculated prospective fault current at the installation point.
3. Continuous current rating — size the rated normal current to the feeder or incomer loading, allowing for future load growth.
4. Impulse withstand and terminal design — confirm whether field deflectors are required on the connection terminals to achieve the target lightning impulse withstand voltage for the specific switchgear architecture.
5. Digital monitoring needs — decide whether TH110 thermal sensors and Easergy Thermal Connect connectivity should be integrated at the design stage to support predictive maintenance programs.
6. Access and operational requirements — consider whether remote racking is needed for operator safety during racking-in/out operations.
7. Documentation and lifecycle management — leverage the QR code-based Digital Logbook for multi-stakeholder projects with EPC contractors, panel builders, and end operators.

Applications

The EasyPact EXE range is intended for a broad span of medium-voltage installations, including infrastructure such as airports and hospitals, large commercial buildings such as high-rise towers, malls, shopping centers and office buildings, industrial plants such as batch process facilities, cement plants, and food and beverage plants, and power grid distribution substations. Its role in each of these settings is protecting people and equipment while enabling reliable power distribution.

Standards and Compliance

The EasyPact EXE fixed circuit breaker’s main electrical characteristics are defined in accordance with IEC 62271-100:2012, the international standard governing high-voltage alternating-current circuit breakers. Additional characteristics referenced within the same IEC 62271-100 framework are covered separately in the manufacturer’s common characteristics documentation, and specifiers should consult the full catalogue for dimensional drawings and any characteristics not included in the summary table above.

Related guides

See also our guides on gas-insulated switchgear, ring main units and metal-clad switchgear.

The Evopact HVX medium voltage vacuum breaker is a digital-ready vacuum circuit breaker (VCB) range built for medium-voltage air-insulated switchgear, designed to protect primary power distribution equipment and connected loads while providing IoT-enabled condition monitoring for improved uptime. This article covers the Evopact HVX range structure, digital connectivity tiers, key ratings, selection criteria, applications and relevant standards for buyers evaluating this breaker for new switchgear or retrofit projects across the Middle East and Gulf (including Egypt and Saudi Arabia), North Africa, CIS, and Sub-Saharan Africa markets.

What Is the Evopact HVX Circuit Breaker?

Evopact HVX is a range of vacuum circuit breakers addressing medium-voltage networks up to 24 kV, with short-circuit breaking capacities up to 40 kA and rated currents ranging from 630 A to 4000 A. It is engineered for installation inside medium-voltage switchgear to connect primary power distribution consumers to the grid, protecting both people and equipment. Unlike a conventional vacuum breaker, the HVX platform is built around embedded sensors, so the breaker itself can report on its own mechanical and electrical health rather than relying solely on periodic manual inspection.

The breaker draws on more than 45 years of Schneider Electric’s medium-voltage engineering experience and is manufactured using best-in-class internal components intended to extend operational life beyond conventional MV breakers.

Range Structure and Digital Connectivity Tiers

A defining feature of Evopact HVX is its scalable digital architecture, offered in three connectivity tiers so a buyer can start with a base breaker and add monitoring capability as facility needs grow:

• EvoPacT HVX – the base digital circuit breaker with future-ready compatibility and fast access to documentation via a QR-code-linked Digital Logbook.
• EvoPacT HVX Active – adds 24/7 condition monitoring using scalable health sensors, starting from essential thermal monitoring, to help react faster to potential faults.
• EvoPacT HVX Active Plus – a comprehensive sensor suite monitoring the complete breaker health, including operating coils, vacuum interrupters, motors and mechanisms.

This tiered approach means the same mechanical breaker platform can be specified as a simple, non-communicating unit or as a fully instrumented digital asset, and upgrades between tiers are designed to be a smooth process once the facility is ready.

Embedded Monitoring Devices

The Evopact HVX digital ecosystem is built from individual monitoring modules that can be combined depending on the selected tier:

Access to breaker documentation and support is simplified through a QR-code-linked Digital Logbook, giving field technicians instant access to manuals and service history on a mobile device.

Key Technical Data

Note: the associated SMX modular switchgear platform referenced alongside HVX in the manufacturer catalog covers air-insulated switchgear applications up to 36 kV, but the HVX vacuum circuit breaker itself is specified for networks up to 24 kV.

Longer Service Life and Endurance

Evopact HVX is presented as proven to last considerably longer than the industry standard for MV circuit breakers, with the manufacturer stating the breaker is built to withstand up to 50,000 mechanical and electrical operations at normal rated current. This endurance figure varies by rated voltage class: 50,000 operations for the 12/17.5 kV class and 30,000 operations for the 24 kV class. Combined with EcoCare condition-based maintenance, the manufacturer notes this endurance can be further extended through predictive, health-driven servicing rather than fixed calendar intervals.

Selection Criteria for Buyers

When specifying an Evopact HVX medium voltage vacuum breaker for a switchgear project, buyers should evaluate:

• Rated voltage and short-circuit duty — confirm the network’s nominal voltage falls within the breaker’s range up to 24 kV and that the rated short-circuit breaking current (up to 40 kA) matches the site’s fault-level study.
• Rated current — select from the 630 A to 4000 A range according to feeder or incomer load requirements.
• Digital tier — decide whether a base breaker, Active (thermal monitoring), or Active Plus (full sensor suite covering interrupters, coils, motors and mechanism) best fits the facility’s maintenance strategy and OT/IT integration plans.
• Endurance class — for high-cycling applications (frequent switching duty), check the applicable mechanical/electrical operations rating for the specific voltage class.
• Service model — evaluate whether an EcoCare membership tier (Essential, Advanced, Advanced+) is available in-region to support remote monitoring, SLA-based intervention, and extended warranty.
• Sustainability requirements — where Green Premium or Cradle to Cradle certification is a procurement requirement, HVX is positioned to meet these criteria.
• Retrofit vs. new build — for aging switchgear, consider EcoFit modernization paths (upgrade to connected assets, retrofit active components, or full replacement) instead of a like-for-like breaker swap.

Applications

Evopact HVX is designed for installation inside medium-voltage switchgear to connect primary power distribution consumers to the grid, and is positioned across several end-user segments:

• Electro-intensive applications — Mining, Minerals and Metals (MMM); Oil and Gas (O&G); Water and wastewater.
• Critical sites — Data centers (co-location and cloud); hospitals.
• Transportation — Airports; railways.
• Commercial buildings — Shopping malls; large office buildings; high-rise condominiums.
• Industrial buildings and infrastructure — Manufacturing facilities; large warehouses.

For these sectors, the breaker’s condition-based monitoring is intended to reduce unplanned downtime risk and support predictive maintenance planning rather than fixed-interval servicing.

Digital Services and Lifecycle Support

Beyond the breaker hardware, the Evopact HVX ecosystem is supported by a services layer:

• EcoCare membership — a three-tiered service plan (Essential, Advanced, Advanced+) offering 24/7 remote monitoring, alarm management, priority expert access and extended warranty options. The manufacturer states this approach can reduce electrical failure risk and unplanned downtime by up to 75%, and reduce on-site maintenance activities and planned downtime costs by up to 40%.
• EcoFit modernization — life-extension and replacement services claimed to extend asset life by up to 25% and, for retrofit of active components, avoid up to 90% of waste versus full replacement.
• EcoConsult — audit, digital twin, system studies and design consultancy services to support asset management strategy.

Standards and Sustainability

Evopact HVX is stated to be tested against major international standards, including IEC, ANSI/IEEE and GB/T frameworks relevant to medium-voltage circuit breakers. On sustainability, the range holds Green Premium and Cradle to Cradle certification, and the manufacturer emphasizes that switching is achieved solely through air-based (vacuum) interruption technology rather than SF6 or other gas-insulated methods. No specific IEC standard number for the breaker itself is specified in the manufacturer catalog beyond this general compliance statement, so buyers should request project-specific type-test certificates confirming applicable IEC ratings for their exact voltage and current class.

Related guides

See also our guides on gas-insulated switchgear, ring main units and metal-clad switchgear.

A compact substation (also called a kiosk substation or package substation) is a factory-assembled, self-contained enclosure that integrates a medium-voltage switchgear compartment, a distribution transformer, and a low-voltage panel into a single weatherproof metal housing designed for fast, low-footprint installation in urban, industrial, or commercial distribution networks. This guide covers the main construction types of compact substations, how they compare with other fixed and mobile substation formats, the criteria buyers should use to specify one, typical application segments, and the governing standards framework. It is written for procurement engineers, EPC contractors, and utility planners across the Middle East and Gulf region (including Egypt and Saudi Arabia), North Africa, CIS countries, and Sub-Saharan Africa who need to source reliable, standards-compliant equipment quickly.

What Is a Kiosk / Compact Substation?

In distribution engineering, a kiosk substation is essentially a “substation in a box.” Instead of building a dedicated masonry substation room, the utility or industrial customer installs a pre-fabricated steel enclosure that already houses the MV switching cells, the transformer, and the LV distribution board, minimizing civil works and commissioning time. This format sits alongside several other recognized substation architectures used in modern grids: building-type (masonry) substations, gas-insulated switchgear (GIS) substations, metal kiosk substations, open-type substations, and step-up/step-down substations.

Because a kiosk substation is delivered largely pre-tested from the factory, it dramatically shortens the on-site installation period compared with conventional open-type or building-type substations, which require dedicated civil construction, cable trenching, and extended site commissioning before energization.

Types and Variants of Compact Substations

Metal-enclosed kiosk substations are the most common compact format, combining ring main unit (RMU)-style MV switching, a distribution transformer, and an LV panel inside a single galvanized or painted steel housing suitable for outdoor or semi-outdoor placement.

Building-type (masonry) substations are the traditional alternative — a dedicated brick or concrete room housing separate MV switchgear, transformer, and LV panels. They offer flexibility for larger transformer ratings but require significant civil works and space, and are generally slower to commission than a factory-built kiosk.

GIS (Gas Insulated Switchgear) substations replace air-insulated busbars with SF6 or alternative gas-insulated compartments, giving a very small footprint and high reliability in constrained or polluted environments. GIS technology is also used in some higher-voltage transmission applications and mobile substation platforms.

Open-type substations are older-generation installations with exposed busbars and equipment in an open switchyard. Many utilities, including TEDAŞ-regulated networks, are actively replacing legacy open-type substations with modern modular or GIS-type substations to improve safety and reduce footprint.

Mobile (transportable) substations are a related but distinct category — wheel-mounted transformer and switchgear packages used for temporary power during maintenance, emergencies, or sudden demand growth, rather than as a permanent installation. A compact kiosk substation is normally installed once and remains in place, whereas a mobile substation is designed to be moved between sites.

Step-up/step-down substations refer to the transformation direction (raising or lowering voltage) rather than the enclosure format, and can be built using any of the above physical constructions, including compact kiosk designs.

Selection Criteria for Compact Substations

When specifying a kiosk or compact substation, buyers should evaluate the following:

• Footprint and site constraints — compact kiosk units are the preferred choice where land is limited, such as dense urban feeders, shopping centers, or industrial plots where a dedicated substation building is not feasible.
• Equipment integration quality — a well-engineered unit should combine properly rated circuit breakers, disconnectors, measuring transformers, protection relays, surge arresters, and modular MV cells within the enclosure, alongside correctly sized cable cross-sections.
• LV integration — buyers should confirm whether LV distribution panels and, where required, battery-rectifier systems for protection and control power are included as part of the package.
• Enclosure robustness and layout — the metal enclosure should be engineered for optimal equipment layout and durability in the target climate, whether coastal, desert, or high-humidity environments common across GEO markets.
• Grounding system design — an advanced, properly engineered grounding scheme is essential for personnel safety and equipment protection, and should be verified as part of the technical offer.
• Short-circuit withstand verification — the switchgear and transformer combination should be validated for worst-case fault conditions, ideally supported by short-circuit analysis rather than assumed ratings.
• Speed of deployment vs. building-type substations — because factory assembly and pre-testing are completed before shipment, kiosk substations typically reach energization faster than masonry substations that require full on-site civil works.
• Compliance and modularity — where applicable, confirm compliance with local distribution utility technical specifications and modular design principles, which support easier future upgrades or capacity changes.

Comparative Overview Table

Note: the table above compares construction formats qualitatively; specific transformer capacity or voltage class should always be confirmed against the buyer’s actual load and network requirements rather than assumed from a generic table.

Applications of Compact Substations

Compact kiosk substations are widely used wherever fast deployment and minimal civil works are priorities:

• Urban and commercial distribution — retail centers, residential complexes, and mixed-use developments where space for a masonry substation building is not available.
• Industrial facilities — factories and processing plants that need a dedicated, secure MV/LV interface close to the load without constructing a separate substation room.
• Utility network modernization — replacing aging open-type substations as part of broader grid upgrade programs.
• Construction and infrastructure projects — large sites such as tunnels, dams, and mining operations often combine compact substations with temporary mobile units during the build phase, before a permanent installation is commissioned.
• Emergency and disaster response — while mobile substations handle the acute emergency phase (earthquakes, floods, storms, conflict-zone damage), compact kiosk substations are frequently the permanent replacement installed once the network stabilizes.
• Remote and military facilities — where a compact, easily transportable enclosure simplifies logistics compared to constructing a full masonry substation on-site.

A relevant engineering reference illustrates how compact substation packages are validated for real-world performance: a published technical study designed a 1600 kVA, 34.5/0.4 kV mobile substation and analyzed its short-circuit behavior in MATLAB Simulink, testing both a direct connection to an infinite bus with 100 MVA short-circuit power and integration into an actual distribution network fed from a 380/34.5 kV GIS substation in Beykoz, Istanbul. Both symmetrical (three-phase) and asymmetrical (phase-to-ground, phase-to-phase) fault scenarios were simulated, and the selected equipment successfully withstood the worst-case short-circuit currents, demonstrating the value of rigorous short-circuit analysis when specifying any compact or mobile substation package.

This type of validation matters for compact substation buyers too: even though the enclosure is smaller, the internal switchgear, transformer, and protection coordination must be engineered to the same fault-current withstand principles as a full-size fixed substation.

Standards and Compliance Notes

Compact and kiosk substations should be specified with reference to the relevant national or utility technical specifications governing MV switchgear, transformers, and enclosure protection for the target market. Utilities in several regions require modular or GIS-type replacements for older open-type installations as part of formal compliance programs. Buyers should request documentation confirming factory testing of the assembled package, short-circuit withstand verification, and grounding system design before shipment, rather than relying on generic catalog claims.

Related guides

See also our guides on medium voltage switchgear, metal-clad switchgear and air-insulated switchgear.

DVCAS MV switchgears are gas-insulated medium-voltage switchgear units, part of Schneider Electric’s SM AirSeT/GIS portfolio, engineered for secondary distribution networks up to 36/38 kV, built around a sealed-for-life stainless-steel tank that keeps live medium-voltage parts insulated and disconnected from ambient conditions. This article covers the DVCAS product architecture, application segments, safety and reliability features, standards compliance, and buyer selection criteria for procurement teams. For engineering, procurement and construction (EPC) contractors and utilities sourcing ring main units (RMUs) across the Middle East and Gulf region including Egypt and Saudi Arabia, North Africa, the CIS, and Sub-Saharan Africa, DVCAS is positioned as a compact, factory-tested solution for demanding grid, industrial, and renewable energy environments.

What Is DVCAS MV Switchgear?

DVCAS is Schneider Electric’s gas-insulated switchgear (GIS) range for secondary distribution, cataloged for voltages up to 36/38 kV. The design integrates disconnector, circuit breaker, and load-break switch functions within a single sealed enclosure, using a familiar three-position switching mechanism (closed, open, earthed) with full mechanical and electrical interlocking to prevent incorrect operating sequences. Because the switchgear ships 100% factory tested for the Compact range, no additional on-site testing is required before commissioning, which shortens installation timelines for export projects where local test infrastructure may be limited.

The core of the DVCAS design is a stainless-steel, fully grounded tank rated to an IP65 ingress protection level, sealed for life for a stated service duration of 40 years. This sealed architecture protects busbars and live components from moisture, dust, and corrosive atmospheres — an important consideration for coastal, desert, and industrial deployment sites common across GEO export markets.

Range Architecture and Functional Modules

DVCAS is structured around modular functional units that can be combined to build a full ring main unit or distribution panel:

• Line functions (D0/ID, ID0/IID, IID0/IIID) — used for incoming/outgoing ring connections in radial and ring-main network topologies, as illustrated in the wind farm collecting substation configurations described in the source documentation.
• Transformer protection function — combined incoming line and transformer protection module, typically paired with a circuit breaker for step-down MV/LV substations.
• Circuit breaker module — for transformer and feeder protection duties.
• Load-break switch and disconnector modules — for ring switching and isolation.

This modularity allows the same DVCAS platform to be reconfigured for solar farm ring architectures, wind turbine array feeders, data center distribution rings, and electro-intensive powerhouse feeders without requiring a different base product line.

Key Specification Table

Selection Criteria for DVCAS MV Switchgear

Buyers evaluating DVCAS or comparable gas-insulated RMUs for a project should assess the following:

1. Rated voltage match to network class. Confirm the project’s nominal system voltage falls within the DVCAS range up to 36/38 kV, and align functional module selection (line, transformer protection, circuit breaker) with the single-line diagram of the substation.

2. Environmental exposure and enclosure protection. For coastal, desert, or high-humidity sites, the IP65-rated sealed tank is a differentiator versus air-insulated alternatives, since disconnection and insulation performance are preserved independent of ambient conditions.

3. Internal arc safety requirements. Where personnel safety codes or utility specifications mandate arc-fault-tested switchgear, confirm testing against IEC 62271-200 with IAC AFL/AFLR classification, and note that overpressure from an internal arc event is managed through an overpressure relief valve at the base of the metal enclosure.

4. Seismic zone requirements. For projects in seismically active regions, verify seismic qualification — DVCAS has been tested per IEEE 693-2005 at 0.5g along with vibration withstand for transport and end-of-life conditions.

5. Commissioning timeline. Where local test facilities are limited or project schedules are tight, the 100% factory-tested Compact range reduces field commissioning workload — a relevant advantage for remote wind, solar, or mining sites across export markets.

6. Digital and metering integration. For data centers and electro-intensive facilities, confirm whether Low-Power Voltage Transformer (LPVT) busbar metering and Low-Power Current Transformer (LPCT) integration are required for protection accuracy and remote monitoring.

Applications

Data centers and mega factories. Large-scale data centers depend on one or two MV substations feeding multiple internal distribution rings via ring main units. DVCAS supports high-density power distribution, flexible outdoor or powerhouse installation, advanced protection schemes, remote monitoring, LPVT busbar voltage metering, and LPCT integration for reduced footprint. Documented deployment includes over 1,000 data center stations equipped with DVCAS.

Wind farms (onshore and offshore). Wind farms typically use a radial network configuration valued for simplicity, cost-effectiveness, and smooth commissioning. DVCAS supports installation either inside the turbine tower or in a separate substation, requires no on-site configuration, and offers internal arc withstand with upward or downward exhaust options. The source documentation reports over 40,000 MW installed worldwide and more than 18,000 wind turbines equipped with DVCAS.

Solar and battery storage (BESS) farms. Solar farm MV distribution is typically built from multiple LV/MV transformer substations grouped into PV power station units and interconnected in a loop configuration, with a single-line diagram including two line functions and one transformer-protection function equipped with a circuit breaker. DVCAS offers an optimized footprint suited to skid or container integration and flexible configurations for varied substation architectures. Over 1,000 solar and BESS stations are equipped with DVCAS.

Electro-intensive industries (energy, chemical, mining, minerals, metals). These sites demand highly reliable power supply with minimal downtime. DVCAS is compatible with powerhouse installation, supports remote monitoring and control, adapts to high-density layouts, and integrates LPVT and LPCT technology. Over 500 electro-intensive stations are equipped with DVCAS.

Oil & gas. DVCAS also serves secondary distribution networks within oil extraction plants and refineries, covering both onshore and offshore installations.

Commercial and industrial buildings. Industrial and infrastructure sites, along with hospitals, represent additional deployment segments for the DVCAS range.

Safety, Reliability, and Standards Compliance

Operational safety in DVCAS is built around mechanical and electrical interlocks that prevent incorrect switching sequences, a simple front-access design for all operations, and full factory testing for the Compact range that eliminates the need for further on-site tests. Internal arc protection is verified against IEC 62271-200 with IAC AFL/AFLR classification, and the switchgear is designed to withstand internal arc events supplied by defined short-circuit current levels for a duration of 1 second, with overpressure managed through a relief valve at the base of the enclosure to protect operators.

The gas-insulated stainless-steel enclosure carries an IP65 ingress protection rating and is sealed for a stated 40-year service life, preventing operator contact with MV live parts. For projects in seismically active regions, DVCAS has been tested to IEEE 693-2005 at a seismic level of 0.5g, described as high seismic performance under ETGI 1020, along with vibration withstand testing covering both end-of-life conditions and vibrations experienced during transport.

Schneider Electric positions DVCAS within a broader track record of 190 years of innovation in delivering reliability, simplicity, and flexibility to industrial and utility customers worldwide.

EcoStruxure Digital Readiness

DVCAS supports EcoStruxure-ready integration, enabling remote monitoring, supervisory control, and reduced downtime for operators managing distributed MV assets across ring main network topologies. Combined with LPVT busbar voltage metering and LPCT current sensing, this allows accurate protection and real-time visibility without the footprint penalty of conventional instrument transformers.

Related guides

See also our guides on metal-clad switchgear, air-insulated switchgear and MV protection relays.