Earthing switches with fault making capacity can be reliably closed against short-circuit currents, thus protecting the operator and switchgear in the cause of inadvertent operation. Naturally, operation behind a closed compartment door forms part of the overall cubicle safety.
|Rated voltage (kV)||12 - 24|
|Rated short-circuit closing capacity (kA)||63 - 110|
There are two forms of earthing switch:
- independent earthing switches and
- earthing switches with combined current transformers.
The current transformers of the combined version form the mounting base for the earthing switch contacts thus reducing the space required in the cubicle.
Every earthing switch is fitted with a spring operating device which makes the closing capacity independent of the operating speed.
The control side of the earthing switch and direction of current can usually be chosen without limitations except for a few models with combined current transformers.