20
5.5 Checking the soundness of vacuums interrupters
Before putting the breaker in service or if any interrupter is suspected for leakage,
then the interrupter shall be checked for satisfactory level of vacuum by applying a
high voltage of 22 kV across the open gap of the interrupter for a period of 1 minute.
Care should be taken to ensure that the external sequential isolators are opened prior
to high voltage application.
5.6 Space heaters
A space heater is provided in the control cabinet. The heater switch must be always
"ON" when the breaker is in service to prevent condensation.
5.7 Final commissioning check
When breaker has been installed and all mechanical and electrical connection
completed, EXCEPT ENERGIZING THE POWER LINE, the following points of
inspection are recommended.
Mechanical and electrical inspection
1.
See that the unit is properly bolted in place and essentially level on its foundation.
2.
Make a check for the tightness of hardware.
3.
See that the operating mechanism is free of packing or foreign material, and
operate freely. Lubrication is generally not required and should be applied
sparingly if necessary.
4.
Terminal connection should be secured tightened.
5.
Check control cable entrance fitting for tightness.
6.
Examine control wiring insulation for evidence of chafing or abrasion. If desired, a
dielectric test can be made, duplicating details of production tests, as described
earlier in this book. Check connections, according to schematic or connection
diagram.
7.
See that all covers and bolted connectors are securely in place.
8.
Make a continuity check, preferably one, which involves measuring resistance in
micro-ohm magnitude, to determine tightness of bolted joints. Also make the over
voltage test on each interrupter for at least one minute. If interrupter has lost the
vacuum, the open contacts quickly flash over, in a positive manner, well before the
adjustable hi-pot tester can reach 28kV.
All the data/ parameters, which are checked and measured, shall be entered in a
commissioning record and kept for comparison. The final trial switching operations
shall be carried out on fully erected circuit- breaker isolated from the high voltage
system and earthed according to recommendations. Once the auxiliary circuit is
connected to the low voltage system, in case of spring charged operating mechanism,
the spring charging motor gets the supply and charges the spring. The supply will cut
off automatically by means of the motor cut off micro-switch. Now, the breaker is
ready for closing operations and the closing operation can be done as described earlier.
Summary of Contents for OVB-SDB
Page 26: ......
Page 49: ...Fig 1 Lifting of Circuit Breaker 50 ...
Page 52: ...Fig 4 Breaker Pole Assembly Refer legend on pg 48 53 ...
Page 53: ...Fig 5 Schematic Circuit Diagram 54 ...
Page 55: ...15029 15027 15028 Fig 7 ESH Mechanism with Cabinet Refer legend on pg 49 56 ...
Page 60: ...Disconnect the motor power supply 7 Fig 15 Motor 61 ...
Page 62: ...Fig 18 The Magnetic Actuator 63 ...
Page 63: ...Notes ...
