Circuit-Breaker Pole; Application Of The X-Ray Emission Standards; Repairs - ABB VD4 Installation And Service Instructions Manual

9.3.3. Circuit-breaker pole

The circuit-breaker pole and relative vacuum interrupter are
maintenance-free until the maximum number of electrical operations
for the type of interrupter is reached (see par. 7.2.3. Trip curves).
The operating life of the vacuum interrupter is defined by the sum of
the ultimate currents corresponding to the specific type of interrupter
in accordance with what is indicated in the graphs of par. 7.2.3. Trip
curves: when the sum of the ultimate currents is reached, the whole
pole must be replaced.
Note
Dismantling and replacement of the pole can only be carried out by
ABB personnel or by skilled and specially trained personnel, particularly
for the necessary adjustments.
To carry out the interrupter test without dismantling the circuit-breaker
pole, use:
– the VIDAR vacuum tester, made by the company Programma
Electric GmbH, Bad Homberg v.d.H.
To check vacuum tightness of the interrupter, the following test values
must be set on the VIDAR tester:
Rated voltage
of the circuit-breaker
12 kV
17.5 kV
24 kV
The test must always be carried out with the circuit-breaker open with
the contacts at the nominal distance (12 kV and 17.5 kV).
Procedure for testing the degree of vacuum of the interrupter of the
circuit-breaker poles:
– urn the power supply off and make the working area safe by following
the safety regulations specified in the IEC/DIN VDE Standards;
– open the circuit-breaker;
– earth a terminal of each circuit-breaker pole;
– connect the earth terminal of the VIDAR tester to the circuit-breaker
structure;
– connect the high voltage terminal of the VIDAR tester to the terminal
of the circuit-breaker pole not connected to earth (L1 phase) and
carry out the test. Repeat the test for phases L2 and L3.
Note
The tester connection cables can produce an indication due to the
capacitive effect. In this case the cables must not be removed.

9.4. Repairs

Replacement of spare parts and accessories must only be carried
out by ABB personnel or suitably qualified and specially trained
personnel.
Always work with the circuit-breaker open and locked so that it cannot
be closed again, with the work area insulated and made safe.
The operating mechanism spring must be discharged.
All power supply sources must be disconnected and made safe
against any reclosing during removal and installation work.
Should maintenance be carried out by the customer's
personnel, responsibility for the interventions remains
with the customer.
The replacement of parts not included in the "List of
spare parts/accessories" (par. 12.1.) must only be carried
out by ABB personnel. In particular:
– complete pole with bushings/connections
– actuator and transmission system
– closing spring set
– opening spring
– shock-absorber.
48
d.c. test voltage
40 kV
40 kV
60 kV
10. Application of the X-ray emission
Standards
One of the physical properties of vacuum insulation is the possibility of
X-ray emission when the interrupter contacts are open.
The specific tests carried out at the PTB laboratories (Physikalisch-
Technische Bundesanstalt, in Brunswick - Germany) show that local
emission at a distance of 10 cm from the interrupter or pole surface,
does not exceed 1 mSv/h.
It follows that:
– at the rated service voltage the use of vacuum interrupters is
absolutely safe;
– application of the withstand voltage at power frequency, according
to the IEC 62271-100 and VDE 0670 Standards, is safe;
– application of a voltage higher than the withstand voltage at power
frequency or of a test voltage in direct current, specified in the IEC
and VDE Standards, cannot be used;
– limitation of the above-mentioned local phenomena, with interrupters
with open contacts, depends on keeping the specific distance
between the contacts.
This condition is intrinsically guaranteed by correct operation of the
operating mechanism and by the adjustments of the transmission
system.