What Are the Differences between Disconnectors, Load Switches, Switch Disconnectors, and Circuit Breakers?


Low voltage switchgear is used to control, protect, switch, and isolate electrical equipment. Switchgear is composed of different circuit breakers, disconnectors, load switches, and switch disconnectors, and each has slightly different applications and functions that serve the primary role of low voltage switchgear in electrical engineering. Edvard Csanyi, founder of Electrical Engineering Portal, does a great job of outlining the basic functions of disconnectors, load switches, switch disconnectors, and circuit breakers with regard to the requirements laid out by IEC 60947.

Disconnectors: A disconnector is used to isolate electrical equipment when it needs to be repaired or inspected as part of a regular maintenance schedule. This is obviously necessary for safety reasons. According to Csanyi, the function of a disconnector is to assure that the flow of electricity has been stopped in a system "from pole to pole and from input to output." Disconnectors can be automatic or manually-operating, depending up on the specific device but are never to be used to interrupt or connect an energized circuit.

Load Switches: On the other hand, load switches are intended to make or break currents under normal, energized circuit conditions. Load switches typically have circuit "making" capacity but lack circuit "breaking" capacity as per IEC 60947-1 and 3. Load switches cannot be switched off, but they can be conducted.

Switch Disconnectors: As you can probably guess by the name, a switch disconnector combines properties of the disconnector and the load switch. This means that it can be used to isolate electrical equipment for the safety feature, but it can also be used to make and break energized circuits. Csanyi says that there are many different types of switch disconnectors in low voltage switch gear as well, including normal switch disconnectors, fuse switch disconnectors, and circuit breakers.

Circuit Breakers: Speaking of circuit breakers, circuit breakers can fulfill the requirements of a load switch or a disconnector. Circuit breakers make, carry, and break currents. Circuit breakers can provide the isolation function if necessary.

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