34 VD4 Vacuum-circuit-breaker | Instruction manual 534/01
- Fit a new contact system back to front on the thin end
of arbor, and slide it forwards onto the thicker part of the
shank.
- Fit arbor onto the relevant contact arm, slide the contact
system over onto the contact arm, and withdraw the
arbor.
- Check all contact fingers and annular tension springs for
perfect fit.
Note:
The set installation position of contact arms must not be
changed by the improper use of force.
8.4.6 Replacement of the withdrawable assembly
(Figures 8/7, 8/10 and 8/11)
- Disconnect plug connector 8.3 (only for withdrawable
assembly of type B)
- Remove interlock rod 46.5 with pin 46.4 from the withdra-
wable assembly
- For motorized withdrawable assemblies, remove the two
socket head bolts which are accessible from below the
assembly
- Unbolt the circuit-breaker from the withdrawable assembly
(4 x M12 bolts)
- Mount the circuit-breaker on a new with drawable assembly
in the reverse order, using new circlip and special pliers for
pin 46.4
- Check the setting of interlocking rod 46.5:
- Turn spindlel 4 anti-clockwise to the stop for the discon-
nected position:
The distance between lever 46.3 and cam 46.2 must be
2+1 mm.
The distance between roller 46.1 and blocking bracket
46.8 must be 0.2-0.5 mm.
- Turn spindle 4 clockwise to the stop for the service
position:
The distance between lever 46.3 and cam 46.2 must be
2+1 mm.
The distance between roller 46.1 and blocking bracket
46.8 must be 0.2-0.5 mm.
- Loosen bolts 46.7 or 46.9 for any necessary adjustment.
8.5 Testing withdrawable parts with a VD4 type
circuit-breaker
When functional tests are carried out on withdrawable parts,
compliance with the con ditions listed below should also be
checked. In this context, a distinction should be made bet-
ween two types of the devices for the VD4 withdrawable part:
- Type A: Withdrawable assembly without inte grated auxiliary
switches (manual operation only).
- Type B: Withdrawable assembly with integrated auxiliary
switches (manual or motorized operation).
8.5.1 Motor-driven withdrawable parts
(non-standard)
Carry out testing of motor-driven withdrawable parts in the
same way as for manually operated withdrawable part:
- Turn off the supply voltage (m.c.b.), since the motor could
otherwise be braked electrically.
- Turn hand crank 5 in the required direction.
Note:
When the withdrawable part moves, the motor turns. The
motor functions in such a case like a generator, i.e. it can lead
to reverse voltages in the terminals.
8.5.2 Checking the correctness of dimensional settings
(Figures 8/7 to 8/11)
1. The distance between lever 46.3 operated by link rod 46.5
and plastic cam 46.2 should be 2+1 mm. If adjustment is
required, release the two bolts 46.6 and 46.7. Deviations
from the specified value can have the following effects:
- Dimensions too large: blocking system for the drive spindle
deactivated.
- Dimensions too small: proper action of the electrical inter-
lock no longer guaranteed.
2. The distance between roller 46.1 and angle lever 46.8
should be 0.2-0.5 mm when the circuit-breaker is closed.
If adjustment is required, release the two bolts 46.7 and
46.6.
8.5.3 Checking auxiliary switch settings on type A withdra-
wable parts
(Figure 8/7)
Compliance with the interlock conditions in the areas of the
test/disconnected position and the service position is ensured
by auxiliary switch -BT3, located in the breaker housing and
factory-set.
In test operations, the withdrawable part must be moved by
hand with the crank fitted.
1. Settings in the area of the test/disconnected position
- Move the withdrawable part out of the test/disconnected
position towards the service position with a few turns of
the crank.
- Slowly move the withdrawable part back to the stop.
- Auxiliary switch -BT3 must then operate when the hand
crank has a remaining angle of ≥ 60° of turn to reach the
stop.
- Slowly insert the withdrawable part from the test/discon-
nected position towards the service position until auxiliary
switch -BT3 just operates.
- In this position, it must still just be possible to move closing
push rod 11.1. For this test, the function of the blocking
magnet -RL2 (dependent on the order) must be deactiva-
ted manually.
- This condition ensures that the electrical interlock takes
effect before the mechanical interlock in the motion se-
quence involved.
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