The liquid-flow control relay protects the on-load tap-changer (OLTC) and, therefore, the transformer itself. If oil flow occurs from the OLTC head to the oil conservator, the flow vane switches the reed, the circuit breakers are tripped and the transformer is de-energized.
Hitachi Energy liquid-flow control relay promptly detects leakages from the energized tap-changer’s oil compartment to the oil conservator and protects the OLTC from damage.
