Switchgear is the equipment that switches, protects and isolates parts of an electrical power system. It brings circuit breakers, disconnectors, earthing switches, fuses, protection relays and measuring transformers together in a metal enclosure, so that a fault can be cleared automatically and a section of the network can be made safe for maintenance.
What switchgear does
- Switches circuits on and off under normal load
- Interrupts fault currents, such as short circuits, before they damage equipment
- Isolates and earths equipment so people can work on it safely
- Measures current and voltage for protection and metering
Main components
- Circuit breaker: interrupts normal and fault current. Medium-voltage switchgear in China mostly uses vacuum circuit breakers
- Disconnector and earthing switch: provide a visible isolation point and connect the circuit to earth
- Load-break switch and fuses: a lower-cost alternative to a breaker for smaller feeders
- Protection relay: detects faults and tells the breaker to trip
- Current and voltage transformers: feed relays and meters
- Busbars: carry power between the panels in a switchgear line-up
Voltage classes
| Class | Typical range | Common products |
|---|---|---|
| Low voltage (LV) | Up to 1 kV AC | Switchboards, motor control centres, distribution cabinets |
| Medium voltage (MV) | Above 1 kV up to 52 kV | Metal-clad panels, ring main units, vacuum circuit breakers |
| High voltage (HV) | Above 52 kV | Gas-insulated switchgear (GIS), outdoor circuit breakers |
Air-insulated and gas-insulated switchgear
Air-insulated switchgear (AIS) uses air between live parts. It is cheaper and easier to extend, but larger. Gas-insulated switchgear (GIS) seals live parts in a gas-filled enclosure, traditionally SF6. It is much smaller and suits city substations, offshore platforms and higher voltages. Some markets now restrict SF6 in new medium-voltage equipment, so check whether your project needs an SF6-free design.
Metal-clad and metal-enclosed panels
Metal-clad switchgear separates the breaker, busbar and cable compartments with earthed metal partitions and usually has a withdrawable breaker that can be racked out for maintenance. In Chinese catalogues these panels are often listed under the KYN28 model series at 12 kV. Fixed metal-enclosed panels, often the XGN series, cost less but need the whole panel to be isolated for breaker maintenance. Low-voltage switchboards are commonly sold as GCS, GCK or MNS types.
What to check when buying switchgear from China
- Rated voltage, rated current and short-time withstand current match your single-line diagram
- Type test reports for the exact design, from an accredited high-voltage laboratory
- Internal arc classification (IAC) for operator safety
- Standard compliance: IEC 62271-200 for MV, IEC 61439 for LV, or UL/ANSI if your market requires it
- Brand and origin of key components: breakers, relays and interrupters
- Factory acceptance test and inspection before shipment
A ranked list of Chinese switchgear manufacturers, with registered company names and direct contacts, is linked below.