Why Do High-voltage Disconnect Switches Sometimes Fail To Open Completely?

A typical scenario is that after prolonged operation, the transmission components inside the operating mechanism of high voltage electrical isolator may become jammed or experience increased friction, preventing the stationary and moving contacts from completing their required travel distance during operation. This results in the tripping operation being performed, but the contacts failing to reach the specified opening distance. Similarly, improper setting of the mechanism limit device or positioning screw can cause deviation in the stroke feedback, making the indication of isolator high voltage inconsistent with the actual position.