Electronic trip unit circuit

Both DK-5AD and 5DD control boxes use electronic releases, and their electrical appliances are shown in Figure 6-81. The tripper has overload long
delay, overload short delay, short circuit instantaneous, current limiting, undervoltage and other protection functions. In the figure, TA is a current-to-voltage converter.
rc is the power transformer, S is the shunt button, SB2 is the reset button, SB3 is the test button, C is the zero voltage delay timer
, Q is the undervoltage trip coil , L is the leakage locking contact , and F is the shunt Trip coil , QF is the auxiliary contact of the circuit breaker .