ABB ConVac Installation And Operation Instruction Manual page 27

M A I N T E N A N C E
7.2.2 Checking the vacuum interrupter
Vacuum interrupter is maintenance free, Should it
become necessary for extraordinary maintenance,
first check if there are any dust, dirt (clean if dirty),
cracks(replace), and other damages due to
dischargement.
As Fig 7b shows，As the contacts wear, the overrun
distance "M" decreases. When distance "M" of any
pole goes below 1 mm with the contactor in the
closed position, all the sub-assemblies must be
replaced.
—
Fig 7b
Caution
Never attempt to adjust the nuts of the vacuum
interrupters for any reason whatsoever. The
overrun distance must be checked, but not
adjusted.
7.3 Maintenance
7.3.1 General requirements
Under normal working conditions, the recommended
maintenance period is the 2、4、7、10、13、16、
18、20 years after the contactor has been put into
service. For harsh environment, frequent operation
and when the customers' requirements on
switchgear is very high, the maintenance period
should be appropriately shortened.
7.3.2 Surface cleaning
If the contactor surface need to be cleaned
according to the inspection in chapter 7.2, please
follow the steps below:
• Before cleaning, the working area must be
segregated in accordance with relevant regulations
and take necessary security measures to prevent
maloperation
• General surface cleaning. Clean dusts and dirt
with a very fine grain emery cloth; For the stains
which are difficult to remove, use weak alkaline
cleaning agent or safe cleaning agent, pay
attention that the cleaning agent is suitable for
plastic and synthetic rubber materials, do not
use carbon tetrachloride or trichloroethylene
and other cleaning agents to clean
• Cleaning of conductors and insulators surface.
For dirt that is easy to remove, use safe cleaning
agent; For those not easy to remove, use low-
temperature cleaner. After cleaning, carefully wipe
away the detergent with an alcohol-stained
cloth and dry it
7.3.3 Checking the degree of vacuum of the
interrupter
The vacuum interrupter is free of maintenance
before reaching the maximum operation cycles.
After 20 years of storage, recommend to sampling
inspect the degree of vacuum of the interrupter.
While reassembly, appropriate adjustments
are necessary. Disassembly and replacement
of the contactor vacuum arching chamber
shall be performed by ABB service engineers.
"m"
Carry out the test on the interrupter without
dismantling it from the contactor and use the
VIDAR tester, manufactured by Programma
Electric GmbH, Bad Homberg v.d.H. company, for
the vacuum test.
The following test values applies:
Contactor rated voltage
7.2 kV
12 kV
The test must always be carried out with the
contactor open, with the contacts at the nominal
distance.
Procedure for testing the vacuum of the interrupter
of the contactor poles:
• Turn off the power and make sure the working
area safety and comply with GB or related safety
regulation requirements
• Connect a terminal of each contactor pole to the
ground
• Connect the ground terminal of the VIDAR tester
to structure of the contactor;
• Connect the high voltage terminal of the VIDAR
tester to the terminal which is not connected to
ground of the contactor pole (phase L1) and carry
out the test. Repeat the test for phases L2 and L3
Caution
The tester connection cables can produce an
indication due to capacitive effect. In this case,
the cables must not be removed.
7.3.4 Other regular maintenance items
In spite of the items in chapter 7.3.1~7.3.3, the
maintenance in the table below should be
considered as well:
27
DC test voltage
25 kV
40 kV