The opening and closing principle of high voltage switches

The opening and closing principle of high-voltage switches mainly involves the coordinated operation of electrical control circuits and mechanical transmission mechanisms, which can be divided into the following three core components:

Electrical control circuit

1. Tripping Operation Procedure

Place the changeover switch QK in the local position, and manually turn the control handle to the trip position (contacts 11/12 close). At this time, the normally open contact QF closes, providing power to the trip circuit.

The anti-pumping relay KLT.A coil is energized, its normally open contact self-holds, triggering the trip coil TQ to operate. After the circuit breaker is fully tripped, TQ is de-energized and reset.

If a short circuit occurs in the line, the secondary current of the current transformer exceeds the set value, the KLT.A coil will be energized, and the tripping action will be completed quickly.

2. Closing Operation Procedure

With the changeover switch QK in the closed position (1/2 contact closed), the closing command is transmitted to the closing relay coil via the 1BS module, supplying it with power.

After the closing coil HQ is energized, it drives the operating mechanism (such as a spring energy storage module), causing the moving contact of the circuit breaker to close with the stationary contact.

After closing is completed, the normally closed contact QF opens, the closing circuit is de-energized, and the spring enters the energy storage state.

Mechanical Transmission Mechanism

Opening Mechanism: After the opening coil TQ is energized, it drives the striking pin via an electromagnet or hydraulic device, causing the opening spring or striking rod to quickly reset, thus separating the contacts.

Closing Mechanism: After the closing coil HQ is energized, the energy storage mechanism releases energy, driving the operating mechanism to complete the contact closing action.

Auxiliary Function Guarantee

Status Feedback: After opening or closing, the auxiliary contact (such as QF) feeds back the circuit breaker position signal to the control circuit to ensure operational accuracy.

Safety Interlocking: "Five-proof" functions (prevention of accidental opening/closing, operation under load, etc.) prevent operational errors.

VTZ-12 Vacuum Circuit Breaker

Summary

VTZ-12 vacuum circuit breaker opening and closing relies on the coordination of electrical control and mechanical transmission. Rapid opening and closing actions are achieved through the control circuit, and operational safety is ensured through auxiliary contacts and interlocking mechanisms.