The RP-400 TLF unit is a compact, highly reliable CT self-supplying protection device. The unit is particularly ideal for backup protection of circuits where the load is a transformer or motor and the switch is a circuit breaker, or it can be used separately as a primary protection.
RP-400 TLF protection device connects CT secondary current directly to fuses, when short circuit, overcurrent, earthing and other faults occur in the protection zone. The fuses will be reliably burnt according to the inverse time limit action characteristics, and within the device, the CT excitation circuit, which is connected to the CT secondary circuit and consists of capacitor and clamping voltage discharge device, is activated without any delay. Besides, it will provide enough energy to drive the circuit breaker tripping coil to realize the tripping to cut off the faulty circuit.