ABB RER620 Technical Manual page 244

Section 4
Protection functions
238
Figure 109: Retrip logic internal design
The retrip function operates with or without a current check selected with the CB fail retrip
mode setting. In "Current check" mode, the retrip is only performed if the current through
the circuit breaker exceeds the Current value level. In "Without check" mode, the retrip is
done without checking the phase currents.
The CB failure mode setting is used to select the mode the breaker fault is detected with.
In "Current" mode, the detection is based on the current level exceeding. In "Breaker
status" mode, the detection is based on the closed position of the circuit breaker after a trip
signal is issued, that is, after a long duration of the trip signal. In "Both" mode, the
detection is based either on the exceeding of Current value level or on the long duration
of the trip signal. When external information of a circuit breaker fault is connected to the
active CB_FAULT input, the retrip function is not allowed to trip. The blocking is used to
disable the whole function.
Back-up trip logic
The operation of the back-up trip logic can be described by using a module diagram when
three phase operation mode is selected:
1MAC309294-MB F
RER620
Technical Manual