The DBT is a digital relay that supervises the integrity of the breaker's tripping and closing circuits. The relay checks the continuity of the coil regardless of the status of the breaker (open or closed). It also includes a time delay in order to avoid misoperations during open to closed transitions. It can supervise three different coils at the same time. It has a DC undervoltage unit which checks the breaker's operating power supply voltage.
Trip circuit supervision
Supervision of breaker coils
Measurement of the breaker's operating DC power supply