Every facility that takes in electrical power needs a place where that power is switched, divided among loads, metered, and - above all - protected against faults. That equipment is switchgear. It is the assembly of breakers, buses, and protective relays standing between the incoming supply and the motors, drives, and panels that use it. This guide explains what switchgear is, what is inside it, how low- and medium-voltage switchgear differ, and its role in oil and gas power distribution.
Switchgear in one line: Switchgear is an assembly of switching and protective devices - circuit breakers, disconnect switches, fuses, busbars, and protective relays - used to control, protect, and isolate electrical equipment. It de-energizes a faulted or serviced circuit safely, distributes incoming power to downstream loads, and provides metering and protection for the system it feeds.
At its core, switchgear combines three functions: switching (connecting and disconnecting circuits with breakers or switches), protection (interrupting fault currents with circuit breakers commanded by protective relays or trip units), and isolation (visibly and safely separating equipment for maintenance). Copper or aluminum busbars carry the incoming power along the lineup, and each outgoing circuit taps off through its own breaker.
Protective relays - or modern microprocessor-based intelligent electronic devices (IEDs) - watch current and voltage and command breakers to trip on overcurrent, ground fault, or other abnormal conditions before damage or fire results. Metering, control power, interlocks, and indicating instruments round out the assembly. Switchgear is typically built into metal-enclosed or metal-clad cubicles for safety and arc containment.
Low-voltage (LV) switchgear operates at or below 1,000 volts (commonly 480 V or 600 V in North American industry) and feeds motor control centers, panelboards, and smaller loads. It usually uses air circuit breakers or molded-case breakers and is the workhorse of plant-floor distribution.
Medium-voltage (MV) switchgear handles roughly 1 kV to 38 kV and is used where power is received at higher voltage or where large motors and long feeders make higher voltage efficient. It uses vacuum or SF6 circuit breakers rated to interrupt very high fault currents. The distinction matters for arc-flash energy, clearances, and the protective relaying scheme, and both types often appear on a single large facility - MV at the incoming service, LV closer to the loads.
Gas plants, compressor stations, LNG terminals, and large production facilities receive utility or on-site generated power and distribute it through switchgear to compressor drives, pump motors, VFDs, MCCs, and utility loads. On generator-backed or islanded sites, switchgear also handles source selection, paralleling, and load shedding, working with automatic transfer schemes to keep critical loads energized.
Protective relays and breakers in modern switchgear are increasingly networked. They report breaker status, currents, voltages, power, and trip events over protocols like IEC 61850, Modbus, or DNP3. A cloud SCADA such as Merobix can read those breaker and metering tags over Modbus or DNP3, giving operators visibility of breaker positions, loads, and trips across remote sites without a trip to the electrical room.
Both distribute and protect power, but switchgear uses draw-out, metal-enclosed circuit breakers with higher fault-interruption ratings and is designed for maintainability and arc containment, often at medium voltage. A switchboard is generally a lower-cost low-voltage assembly with fixed-mounted breakers for smaller distribution duty.
Switchgear distributes and protects feeders and large circuits with circuit breakers, sitting upstream in the power system. A motor control center (MCC) is a lineup of motor starters and drives that a feeder from switchgear supplies. Put simply, switchgear feeds the MCC, and the MCC starts the motors.
Low-voltage switchgear operates at or below 1,000 V, commonly 480 V or 600 V in industry. Medium-voltage switchgear covers roughly 1 kV to 38 kV. The rating is chosen for the incoming service voltage and the fault current it must safely interrupt, which drives clearances, breaker type, and arc-flash energy.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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