| Low-Voltage Switchgear Assembly | Up to 1,000 V AC | Air circuit breakers, molded-case circuit breakers, fuses, contactors, and protective relays | Power distribution, overload protection, short-circuit protection, isolation, and metering | Commercial buildings, factories, data centers, infrastructure, and utility substations | Modular construction; fixed or withdrawable circuit-breaker compartments; copper or aluminum busbars | IEC 61439-1 and IEC 61439-2 |
| Metal-Enclosed Medium-Voltage Switchgear | Typically above 1 kV to 36 kV | Vacuum circuit breakers, load-break switches, fuses, earthing switches, and protection relays | Feeder control, fault interruption, busbar protection, isolation, and safe access control | Industrial plants, commercial power systems, renewable-energy plants, and distribution substations | Compartmentalized metal enclosure; may use fixed or withdrawable circuit breakers | IEC 62271-200 |
| Metal-Clad Switchgear | Commonly medium voltage up to approximately 38 kV | Withdrawable vacuum circuit breakers, instrument transformers, relays, and grounding switches | High-reliability switching, feeder protection, equipment isolation, and arc-fault risk reduction | Utility substations, heavy industry, mining, transportation, and large manufacturing facilities | Separate grounded metal compartments; withdrawable breakers support maintenance and testing | IEEE C37.20.2 and applicable local electrical codes |
| Gas-Insulated Switchgear | Medium and high voltage; designs range from several kilovolts to transmission voltages | Circuit breakers, disconnectors, earthing switches, current transformers, and voltage transformers | Compact power switching, fault interruption, busbar sectionalizing, and electrical isolation | Urban substations, indoor substations, offshore facilities, renewable-energy hubs, and space-limited sites | Sealed metal enclosure with insulating gas or gas mixture; small footprint and protected internal conductors | IEC 62271-203 for gas-insulated metal-enclosed switchgear above 52 kV |
| Hybrid Insulated Switchgear | Medium to high voltage | Combined circuit breakers, disconnectors, earthing switches, and air-insulated or gas-insulated bus sections | Power switching and protection where reduced footprint is needed without fully gas-insulating every section | Substation extensions, wind farms, solar plants, industrial networks, and constrained sites | Combines air-insulated and gas-insulated technologies; can simplify retrofit projects | Applicable parts of the IEC 62271 series |
| Ring Main Unit | Typically 6 kV to 36 kV | Load-break switches, circuit breakers, fuses, disconnectors, and earthing switches | Ring-network switching, transformer protection, feeder isolation, and supply continuity | Urban distribution networks, commercial developments, apartment complexes, and compact substations | Compact, sealed or compartmentalized construction; often configured with two ring ways and one transformer way | IEC 62271-200 and IEC 62271-103, according to the equipment configuration |
| Motor Control Center | Usually up to 1,000 V AC | Circuit breakers, fuses, contactors, overload relays, soft starters, and variable-speed drives | Motor starting, stopping, speed control, overload protection, short-circuit protection, and monitoring | Manufacturing plants, water treatment facilities, HVAC systems, process industries, and pumping stations | Grouped motor feeders in a common enclosure; available with fixed or withdrawable units | IEC 61439-1 and IEC 61439-2 |
| Automatic Transfer Switchgear | Low voltage, commonly up to 1,000 V AC | Mechanically or electrically interlocked circuit breakers, transfer switches, and control relays | Transfers critical loads between normal and emergency power sources | Hospitals, data centers, emergency systems, airports, commercial buildings, and industrial plants | Prevents unintended paralleling of sources unless specifically designed for closed-transition operation | IEC 60947-6-1 and applicable installation standards |