When electrical equipment is being repaired, the power must be cut off, separated from live parts, and an effective isolation distance must be maintained. Require a withstand voltage level that can withstand the overvoltage between its fracture surfaces. Knife switch is a switching device used as an isolated power source. The knife switch that isolates the power supply is also called an isolation switch.

The use of a knife switch for isolation generally belongs to an unloaded circuit breaker, which can only connect or disconnect "negligible currents" (referring to the capacitive current of a busbar with voltage, the current of a short cable or voltage transformer). Some knife switch switches have a certain breaking capacity, and when their breaking capacity is suitable for the required breaking current, they can turn on or off some electrical equipment or complete sets of equipment under non fault conditions.

The knife switch used as an isolation switch must meet the isolation function, that is, the switch has a clear fracture and the fracture distance is qualified.

The knife switch and fuse are connected in series to form a unit called the knife switch fuse group; When the movable part (moving contact) of the knife switch is composed of a fuse carrier with a fuse link, it is called a fuse type knife switch.

Knife switch fuse combination and additional auxiliary components, such as operating rod, spring, arc knife, etc. It can be combined into a load switch. The load switch has the ability to turn on or off the load current under non fault conditions, and has a certain short-circuit protection function.

Knife switch maintenance:

1) Check if the load current exceeds the rated value of the knife switch;

2) Check whether there is poor contact between the moving and stationary contacts, heating, burning of the moving and stationary contacts, and wire (body) connection in the conductive part of the knife switch. In case of the above situation, repair it in a timely manner;

3) Check for burns and discharges on insulation components such as connecting rods and bases;

4) Check whether the components of the switch operating mechanism are intact and flexible, and whether the three phases are synchronized and accurately in place during opening and closing.