GE Industrial Solutions AKD-20 Low Voltage Switchgear - Manuel (Page 51)

AKD-20 Low-voltage Switchgear
Chapter 6. Testing and Inspection
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All components, except the Neutral Sensor, are integrally mounted
in the circuit breaker. When used, the Neutral Sensor is separately
mounted in the bus or cable compartment of the switchgear. In
drawout construction, it is automatically connected to the trip unit
in the breaker via a drawout secondary disconnect block.
CAUTION: Never disengage the trip unit on a breaker that is
energized and carrying load current. This will open-circuit the
current sensors, allowing dangerous and damaging voltages to
develop.
ATTENTION: Il ne faut jamais désengager le déclencheur d’un
disjoncteur qui est sous tension et transporte un courant de
charge. Cela ouvrira les circuits des détecteurs de courant,
permettant le développement de voltages dangereux et
dommageables.
Complete Instructions for testing the trip units are included with
the test set. The trip unit users manuals are DEH-4567
(Entelliguard trip unit) and DEH-4568 (GTUTK20).
6-5 Final Steps to Be Taken Before
Energizing Equipment
The following steps should be taken before energizing the
equipment:
1. Manually exercise all switches, circuit breakers, and other
operating mechanisms to make certain they are properly
aligned and operate freely.
2. Conduct an electrical insulation resistance test to make sure
the switchgear is free from short circuits and grounds. This
should be done both phase-to-ground and phase-to-phase
with the switches or circuit breakers both opened and
closed. This test should be performed with a 1000 volt
meggar. Disconnect all control circuits before checking
resistance.
3. Check any electrical relays, meters, or instrumentation to
determine that connections are made properly and the
devices function properly.
4. Electrically exercise all electrically operated circuit breakers,
and other mechanisms (but not under load), to determine
that the devices operate properly. An auxiliary source of
control power may be necessary to provide power to the
electrical operators.
5. Test the ground fault protection system (if furnished) in
accordance with the manufacturer's instructions.
6. Set the adjustable current and voltage trip mechanisms to
the proper values. Experience has indicated that damage
from faults can be reduced if the devices used for overload
and short circuit protection are set to operate
instantaneously (that is, without intentional time delay) at
115 percent of the highest value of phase current which is
likely to occur as the result of any anticipated motor starting
or welding currents.
7. Make certain that field wiring is clear of live bus and, where
necessary, physically secured to withstand the effects of
fault currents.
8. Check to determine that all grounding connections are
made properly.
9. Remove all debris, scrap wire, etc., from the switchgear
interior before closing the enclosure.
10. Install covers, close doors, and make certain that no wires
are pinched and that all enclosure parts are properly
aligned and tightened.