ABB UniGear 500R - Page 69

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9.3.2 Maintenance in the low voltage compartment
9.3.2.1 Checking of correct operation of the
protection release
 Make the plant you want to work on safe (follow
the plant safety regulations).
 Move the three-position disconnector to EARTH
position and close the circuit breaker.
 Withdraw the protection release from the fixed part
fixed onto the door of the low voltage
compartment.
 Using current and volumetric test boxes, carry out
injections to check perfect operation of the
protections themselves.
Note: To check operation of the protection releases,
refer to the operating manual of the protection
provided by the manufacturer.
9.3.2.2 Cleaning and checking the auxiliary
connections
 Make the plant you want to work on safe (follow
the plant safety regulations).
 Move the three-position disconnector to EARTH
position and close the circuit breaker.
 Open the miniature circuit-breakers (Figure 115)
positioned inside the low voltage compartment to
remove the auxiliary power supply to the panel.
 Carry out a visual inspection on all the cabling,
terminal boxes (Figure 115) and check for any
presence of dirt.
 Manually check correct insertion of the cabling in
the terminal box.
9.3.2.3 Measuring the insulation resistance of the
auxiliary circuits
 Make the plant you want to work on safe (follow
the plant safety regulations).
 Move the three-position disconnector to EARTH
position and close the circuit breaker.
 Open the circuit-breakers (Figure 115) positioned
inside the low voltage compartment to remove the
auxiliary power supply to the panel.
 From one of the circuit-breakers (Figure 115)
disconnect the wires on the internal side of the
panel.
 Using a Megger instrument, measure the
resistance between the phase involved and the
conductive electric part (switchgear structure). The
value must not be less than 2 MOhm and in any
case constant over time.
 Repeat the operation for the number of circuits
(circuitbreakers) inside of the panel (110 V dc, 220
V ac, etc).
 Replace the connections and put the panel into
service.
Figure 115: Low voltage compartment.