ABB OVB-SDB, Instructions Manual

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If trip command is initiated now, it will pull the latch (Ref. Fig. L). Hence its
engagement with the latch assembly will break. This will move the latch assembly
La in downward direction. Downward movement of latch assembly will release the
latch Lb. Hence there is no more pressure or any engagement that will retain the
current poison of arm and leverage. Arm and leverages are free to move now. As
previously discussed these components are directly connected to charging shaft.
Tripping spring directly exerts pressure on the shaft via tripping lever. As leverage
becomes free to move tripping spring will pull back the tripping lever and open the
circuit breaker.
Lever
Fig. L Circuit Breaker in open condition