41
N.
Fig. 8g
Caption
No.
Number of closing-opening cycles allowed for the vacuum interrupters.
Ia
Breaking capacity of the vacuum interrupters.
7.3.
Preliminary operations
– Clean the insulating parts with clean dry cloths.
– Check that the top and bottom terminals are clean and free of any
deformation caused by shocks received during transport or storage.
7.4.
Installation of fixed circuit-breakers
The circuit-breaker can be mounted directly on supporting frames to
be provided by the customer, or on a special supporting truck (available
on request).
The circuit-breaker, with supporting truck, must be suitably fixed to
the floor of its own compartment by the customer.
The floor surface in correspondence with the truck wheels must be
carefully levelled.
A minimum degree of protection (IP2X) must be guaranteed from the
front towards live parts.
7.4.1.
Mounting the circuit-breaker on a truck made by other
manufacturers
The VD4 circuit-breakers which are not installed on ABB trucks, but
on trucks made by the customer, must be fitted with one or two
additional auxiliary contacts (activated by the mechanical lock and by
the circuit-breaker release device) to carry out the function of
interrupting the shunt closing release circuit (-MC) during traverse
from isolated and vice versa.
In ABB trucks, this function is carried out by the -BT1 and -BT2
auxiliary contacts which cut of the release power supply during and
before activation of the mechanical lock of the screw truck racking-in
device. This means that the shunt closing release power supply can
only by applied at the end of activation of the mechanical lock. In this
way it is certain that no electrical impulse can activate the shunt
closing release with the circuit-breaker in an intermediate position.
7.5.
Installation of withdrawable circuit-breakers
in UniGear ZS1 switchgear and PowerCube
modules
The withdrawable circuit-breakers are preset for use in UniGear ZS1
switchgear and PowerCube modules.
For racking-in/racking-out of the switchgear, fully insert the lever (1)
(fig. 9) in the appropriate seat (2) and work it clockwise for racking-in,
and anti-clockwise for racking-out, until the limit switch positions are
reached.
Circuit-breaker racking-in/-out must be carried out gradually to avoid
shocks which may deform the mechanical interlocks and the limit
switches.
The torque normally required to carry out racking-in and racking-out
is <25 Nm.
This value must not be exceeded. If operations are prevented or
difficult, do not force them and check that the operating sequence is
correct.
Note
To complete the racking-in/out operation, about 20 rotations of the
lever are required for circuit-breakers up to 17.5 kV, and about 30
rotations for 24 kV circuit-breakers.
When the circuit-breaker has reached the isolated for test/isolated
position, it can be considered racked into the switchgear and, at the
same time, earthed by means of the truck wheels.
Withdrawable circuit-breakers of the same version, and therefore
with the same dimensions, are interchangeable. However, when, for
example, different electrical accessory fittings are provided, a different
code for the plug of the auxiliary circuits does not allow incorrect
combinations between panels and circuit-breakers.
For the circuit-breaker installation operations, also refer to the technical
documentation of the above-mentioned switchgear.
The racking-in/-out operations must always be carried
out with the circuit-breaker open.
7.5.1. Circuit-breakers with withdrawable motorized truck
Carry out the racking-in/racking-out test of the motorized truck in the
same way as for a manual truck, following the instructions below:
– Rack the circuit-breaker into the switchgear in the open and iso-
lated position, with the power supply to the motor circuit cut off and
with the enclosure door closed.
– Insert the manual racking-in lever (1) in the special coupling (2) Fig.
9, and take the motorized truck to about half its run between the
isolated for test and the connected position.
The torque needed to carry out truck handling is < 25 Nm.
In the case of accidental inversion of the truck motor power supply
polarity, this operation allows a possible error in direction to be dealt
with without any damage. Verification checks:
a) motor rotation
clockwise
during circuit-breaker racking-in.
b) motor rotation
anticlockwise
during circuit-breaker racking-out.
– Remove the manual lever (1) from the coupling (2) Fig. 9
– Supply the truck motor circuit.
– Activate the control for the electrical racking-in operation. When
racking-in has taken place, check correct changeover of the rela-
tive auxiliary contact.
– On completion, activate the control for the electrical racking-out
operation. When racking-out has taken place, check correct
changeover of the relative auxiliary contact.
– In the case of a motor fault during a racking-in or racking-out opera-
tion, in an emergency the truck can be taken to the end of its run
manually, after first cutting off the power supply to the motor power
supply circuit and then, using the manual lever, work in the same
way as with the manual truck.
Note
By means of the chain transmission, truck handling carried out
using the manual lever makes the truck motor armature rotate
which, behaving like a generator, can cause inverse voltage at
the connection terminals.
This may damage the permanent magnet of the motor, there-
fore all the truck racking-in and racking-out operations carried
out using the manual lever must be done without power supply
in the motor circuit.
