Relay operates for 1 phase, 2 phase and 3 phase fuse failure in the supervised circuits and for an interruption in any of the cables or their associated fuses.
When a fuse blows, the relay operates fast enough to inhibit the undesired operation of high speed distance relays.
Uses the principle of instantaneous amplitude comparison of two voltages used for Fuse failure relay.
This is achieved with two voltages , one before the fuse and the other after the fuse.
Under normal operating conditions, the two voltages give rise to zero resultant voltage, thus no operation of Fuse failure relay.
When the fuse blows out, the neutralizing effect is lost, hence Fuse failure relay operates.
Definitions CSD (Controlled Switching Device): A device that is installed at the relay and control panel to overcome the transient behaviour of voltage and current during switching. This device synchronizes the switching of each pole of the circuit breaker according to the zero crossing of the corresponding phase. This device is also known as a phase synchronizing device, or PSD for short. Requirement When we switch off an online circuit breaker to disconnect an inductive load, we ideally want to interrupt the current of the system at the zero crossing of the current waveform. However, this is practically impossible to achieve. In a normal circuit breaker, the current interruption may occur near the zero crossing point, but not exactly at it. Since the load is inductive, this sudden interruption of current causes a high rate of change of current (di/dt), which results in a high transient voltage in the system. In low or medium voltage power systems, this transient voltage during circui...