Why Can High-voltage Disconnect Switches Only Operate In A No-current State?

high voltage isolator is a mechanical device used to disconnect a circuit and create a visible break point, facilitating equipment maintenance or changes in operating mode. The original design purpose of the high voltage isolator switch was to enable maintenance personnel to clearly determine whether a circuit is broken, rather than to cut off the current that is being transmitted.

hv isolator's internal structure does not include an arc-extinguishing mechanism, meaning that the arc cannot be quickly extinguished when the contacts separate. When the current is interrupted while the circuit is energized, a high-temperature arc will be generated between the contacts, which will not only cause ablation to the hv isolator switch itself, but may also damage the surrounding insulating components.

In high-voltage system operating procedures, the current is typically interrupted by a circuit breaker or load switch before operating high voltage electrical isolator to create a visible break point. This sequence conforms to electrical industry safety regulations and provides more reliable physical isolation for maintenance work.

Attempting to operate isolator high voltage while the circuit is energized can result in a long arc or even a flying arc, posing a serious risk to equipment and personnel.