ABB VD4 Installation And Service Instructions Manual page 21

D I S T R I B U T I O N S O L U T I O N S
5.5.1 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 isolated position, with the power supply
to the motor circuit cut off and with the enclosure
door closed.
• Insert the manual racking-in lever in the special
coupling 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 from the coupling
• 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 relative auxiliary
contact.
• On completion, activate the control for the elec-
trical 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 operation, 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, therefore 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.
5.6 Power circuit connections of
fixed circuit breakers
5.6.1 General recommendations
• Select the cross-section of the conductors
according to the service current and the short-
circuit current of the installation.
• Prepare special pole insulators, near the terminals
of the fixed circuit breaker or of the enclosure,
sized according to the electrodynamic forces
deriving from the short-circuit current of the
installation.
5.6.2 Assembly of the connections
• Check that the contact surfaces of the
connections are flat, and are free of any burrs,
traces of oxidation or deformation caused by
drilling or impacts received.
• According to the conductor material and the
surface treatment used, carry out the operations
indicated in table T1 on the contact surface of the
conductor.
Assembly procedure
• Put the connections in contact with the circuit
breaker terminals, taking care to avoid mechanical
stresses (traction / compression) on, for example,
the conducting busbars on the terminals.
• Interpose a spring washer and a flat washer
between the head of the bolt and the connection.
• It is advisable to use bolts according to DIN class
8.8 Standards, also referring to what is indicated
in table T2.
• In the case of cable connections, strictly follow the
manufacturer's instructions to make the terminals.
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