Operation And Maintenance; Appendix A - Gas Sampling Device - COMEM BR Manuel D'instruction

Operation and maintenance

The Buchholz Relay is ready for immediate operation after
installation and electrical connection .
Operation
It is possible to detect the gas accumulation in two
different way:
• Checking the graduated windows
• Checking the gas accumulation alarm signal
It is possible to verify the dampers status:
• Checking the alarm/trip signal
Maintenance
No special maintenance is required during operation.
COMEM recommends performing the following checks:
• Check the exterior condition of the device
• To verify the functioning of the switches by following the
paragraph Mechanical Test
• Check the gaskets condition and if there is any leakage.

Appendix A - Gas Sampling Device

6
Figure E
Principle
The gas sampling device has been designed to collecting
the oil in a readily accessible position, typically on the side
of the transformer.
Description of operations
During normal operation the Buchholz relay is full of oil
and is connected to the gas sampling device (GSD) via
pipelines 10 and 11.
Valves (8), (2) and (9) are open.
Valves (3), (4), (6) or (7) are closed.
8
8
9
11
1
2
7
5
Movement, transport and storage
The Buchholz Relay storage must remain in the original
packaging and in a dry place with temperature range betwe-
en -10°C to 40°C.
Upon receiving the Buchholz Relay, please check:
• The outer surface of the packaging to check that it is
intact.
• That there are no breakages to the packaging.
If damages are found, please contact COMEM, providing
the data given on the shipping list and the serial number of
the buchholz relay Buchholz Relay.
Do not paint the device. In this case any guarantees concerning
the corrosion resistance will decline.
Only mild soap and water should be used
to clean the electrical box cover. Solvents must not be used for
any reason as they will degrade the performance of the paint.
Use of solvents on the unit will immediately void the warranty.
The gas sampling device is consequently also full of oil.
Sampling procedures are as follows:
• To sample oil: open valve (6) or (4).
• To sample gas if the relay has signaled alarm or tripped
the transformer:
• Open valve 4 and let the oil inside the device to flow
out. This draws any gas from the relay via valve (8),
tube (11) and valve (2) into the body of the GSD. The
progress of this operation can be checked through the
10
inspection porthole.
• When the desired amount of gas has been collected,
close valves (2) and (4) and open valve (3) to take the
sample.
3
• To test satisfactory operation of the alarm and trip
circuits proceed as follows:
• Close valve (2) then drain all the oil from the device by
opening valves (3) and (4).
4
• Connect an air pump (as bicycle pump) to valve (5).
• Close valves (3) and (4) and pump fast whilst
simultaneously opening valve (2).
The air will then pass into the upper chamber of
the Buchholz relay via pipeline (11) lowering the floats and
consequently closing their contacts. If you wish to test the
lower float then first the valve between the relay and the
conservator must be closed to prevent air from
flowing directly into the conservator.
Note:
After the commissioning be sure that the Buchholz relay
and the GSD are both filled with oil.
BUCHHOLZ RELAYS
CAUTION