Medium Voltage Switchgear Buying Guide
Medium voltage switchgear is a coordinated protection and control assembly. Voltage, current and fault duty are only the opening data; the single-line diagram, protection philosophy, room layout and test scope decide the final configuration.
Short answer: Record nominal voltage, frequency, source arrangement, transformer capacity, feeder count, bus sectioning, earthing method and downstream loads. A lineup cannot be selected correctly from a generic voltage class alone.
Start with the single-line diagram
Record nominal voltage, frequency, source arrangement, transformer capacity, feeder count, bus sectioning, earthing method and downstream loads. A lineup cannot be selected correctly from a generic voltage class alone.
Rated current and fault duty answer different questions
Rated current describes normal continuous carrying capability. Short-time withstand and breaking ratings relate to fault conditions. Both must coordinate with the calculated fault level, protection clearing time and upstream source.
Protection, metering and interlocking
Confirm relays, CT and VT ratios, trip coils, communications, metering, mechanical key interlocks and arc-flash or internal-arc requirements where applicable. These are project functions, not decorative options.
Room layout and cable interfaces
Check indoor or outdoor construction, clearances, lifting route, front or rear access, cable entry, termination space, earthing bar, ventilation and maintenance isolation.
Documents and acceptance
Agree drawings, nameplates, wiring diagrams, relay settings responsibility, routine-test records, witness testing and applicable standard before manufacture.
| Network point | Why it must be confirmed |
|---|---|
| Nominal voltage and insulation level | Determines the equipment class and clearances |
| Rated current | Matches continuous load and temperature rise |
| Fault withstand and breaking duty | Coordinates with the calculated short-circuit duty |
| Protection and interlocking | Defines safe operating and isolation sequences |
Information to prepare before requesting a quotation
- Single-line diagram and system voltage
- Rated current, fault level and protection-clearing time
- Transformer and feeder data
- CT/VT, relay, metering and communication requirements
- Cable entry, termination and room layout
- Applicable standard, drawings and test scope
Frequently asked questions
What rating matters most for switchgear?
No single rating is enough. Nominal voltage, rated current, short-time withstand, breaking duty, protection and installation data must work together.
Can switchgear be chosen from transformer kVA?
Transformer capacity is an input, not the complete answer. Fault level, feeder arrangement and protection coordination are also required.
Need a configuration review?
Send the measurements, installed references and required result for Medium Voltage Switchgear Buying Guide. Geararo can identify open compatibility questions before the quotation is finalized.
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