When the higher voltage circuit breaker is tripped after a heavy internal fault, by protection which cannot conveniently provide an auxiliary contact with a dwell time long enough to ensure correct tripping of the lower voltage circuit breaker. Typically the relay is initiated by transformer protection, such as overall differential where both the HV and LV circuit breakers are to be tripped simultaneously. The HV circuit breaker may be expected to trip more quickly than the LV breaker. So the tripping signal is maintained by the delayed resetting, to ensure complete clearance by the fault may have been cleared largely by the HV circuit breaker and the protection has started to reset. Therefore a good solution is applying of trip relay with suitable drop off time in LV voltage side for remaining of protection system trip command on LV circuit breaker for enough time.