What is the relationship between the protective voltage, protective current, and operating voltage of a vacuum circuit breaker in an AC power grid?

The relationship between the protective voltage, protective current, and operating voltage of a vacuum circuit breaker in an AC power grid is as follows:

• Protection signals are usually issued by relay protection devices, triggering operation by collecting data from instrument transformers (such as AC current or voltage). For example, overcurrent protection and differential protection rely on AC signals to detect faults.
•  The protection function itself is implemented by the relay protection device; the circuit breaker only executes trip commands and does not directly participate in the voltage or current protection logic.

• Operating voltage (control circuit voltage) can be an AC or DC signal. For example, the opening and closing coils are usually driven by a DC power supply, but the control signal may be transmitted through an AC circuit.
• If the DC power supply fails, the relay protection device may not function properly, leading to protection failure.

Protection signals: Mostly AC signals (such as current and voltage), used for fault detection.

Operating signals: Can be AC ​​or DC, used to control the operation of the vacuum circuit breaker.