Problem -1
A Circuit Breaker opened from the remote end for some outage work . After complete the work breaker was tried to close again, but "R" phase CB pole not closed and other two poles are closed .
Immediately Pole Discrepancy Stage -1 operated and closed breaker poles are opened.
CB was taken outage for further investigation.
1.+ve & -ve is checked across contact K1 - ok.
2. Individual coil resistance - ok
3. Function of K1 checked - ok
4. CB was closed by manually press the closing coil nob. Again locally CB was tried to close. All three phases are closed. We thought there is struck up in the close coil nob. So again CB tried to close but this time same problem happened.
5. Resistance checked between point A & B
R- Phase = 90 ohms Y= 40 ohms B= 40 ohms
The resistance R1 not shown in the drawing . So we desired wire problem between coil and point 'A'. Then the R1 was found between between coil and point 'A'.
A wire connected in the resistance was found disconnected. And circuit taken full resistance value. So the enough current was not flowing through the coil to pickup.
Problem -2
When close the CB , " R" Pole oil pressure comes to "0" point. Pole was not closed. Same PD- Stage 1 operated and other poles are tripped.
Then closing coil nob was properly pulled out. Oil pressure was increased by manually up 10Mpa. Then motor was ON and pressure got normal.
The same problem will happened if CB close with "0" pressure.
