the power supplied to the release during and before
activation of the mechanical lock of the truck’s
screw insertion device. This means that power can
only be supplied to the shunt closing release after
activation of the mechanical lock. No electrical
impulse is therefore able to activate the shunt
closing release when the circuit-breaker is in the
intermediate position.
7.5. Installation of withdrawable
circuit-breakers
The withdrawable circuit-breakers are designed for
use in UniGear ZS1 switchgear.
To rack the circuit-breaker in and out of the
switchgear, fully insert the lever (1) (fig. 9) into its
seat (2) and turn it clockwise to rack-in or counter-
clockwise to rack-out until reaching the end of travel
positions. The circuit-breaker must be gradually
racked-in and out to avoid shocks that could deform
the mechanical interlocks and limit switches.
The torque normally required for racking-in and out
is <
25 Nm.
Never exceed this value. If the operations are
obstructed in any way or difficult to perform, do not
apply force but check that the operating sequence is
correct.
Note
To complete the racking-in or out operations, the lever must be turned
about 20 times for circuit-breakers up to 17.5 kV and about 30 times for 24
kV circuit-breakers.
When the circuit-breaker has reached the isolated
for test/isolated position, it can be considered to
have been racked into the switchgear and earthed
by means of the truck wheels.
Withdrawable circuit-breakers of the same version,
thus of the same size, are interchangeable. However,
when, for example, the electrical accessories are
different, the plug of the auxiliary circuits will have a
different code and prevent panels and circuit-
breakers from being wrongly paired.
The technical documentation of the switchgear
should also be consulted when installing the circuit-
breakers.
• The racking-in/out operations must
always be performed with the circuit-
breaker open.
• When putting into service for the first
time, always load the circuit-breaker
operating mechanisms in the manual
mode to avoid overloading the
auxiliary supply circuit.
7.5.1. Circuit-breakers with motor-operated
withdrawable trucks
Perform the racking-in/out test for the motor-
operated truck in the same way as the manual truck
and comply with the following instructions:
• Rack the circuit-breaker into the switchgear in the
open and isolated position, with the supply circuit
of the motor de-energized and the enclosure door
closed.
• Fit the manual racking-in lever (1) into its seat (2)
Fig. 9 and move the motor-operated truck to about
halfway along its travel, between the isolated for
test and connected positions. The torque required
to move the truck is <
25 Nm.
• This operation allows you to deal with movements
in the wrong direction without damage should the
polarity of the truck motor supply accidentally
reverse. Verifications:
a) clockwise motor rotation when circuit-breaker
is racked in.
b) counter-clockwise motor rotation when circuit-
breaker is racked out.
• Remove the manual lever (1) from its seat (2) Fig. 9
• Energize the truck motor circuit.
• Activate the operating mechanism for electrical
racking-in. After racking-in, make sure that the
relative auxiliary contact has switched correctly.
• At the end of the sequence, activate the operating
mechanism for electrical racking-out. After
racking-out, make sure that the relative auxiliary
contact has switched correctly.
• If a motor fault occurs during a racking-in or out
operation, the truck can be moved to end of travel
in an emergency by first shutting off the voltage
supplied to the motor supply circuit and then
using the manual lever in the same way as for truck
operation in the manual mode.
Note
When the manual lever is used to operate the truck, the chain transmission
turns the truck motor which, by acting as a generator, can produce reverse
voltage towards the connection terminals.
Since this can damage the permanent magnet of the motor, all truck
racking-in and out operations with the manual lever must be performed
with the motor circuit de-energized.
M ED I U M VO LTAG E PRO D U C T S
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