Manual | MNS-SG Operation and Maintenance 39
OPEN the circuit breaker before racking.
*The column heading DC WITHSTAND is a reference for those using DC tests to
verify the integrity of connected switchgear. It represents values believed to
be appropriate and approximately equivalent to the corresponding power
frequency withstand test values specified for each voltage class of switchgear.
The presence of this column in no way implies any requirements for a DC
withstand test on AC equipment. Also, it does not imply that a DC withstand
test is an acceptable alternative to ANSI C37.20 for design, production or
conformance tests. When making DC tests, raise the voltage to the test value
in discrete steps and hold for one (1) minute.
4.
With the main circuit dead, check the continuity of all
circuits after installing the circuit breakers.
Energize the control source and operate the equipment.
Indicating instruments verify the continuity of current
transformer circuits after energizing the main circuit.
Test the control circuit by following these steps.
The breaker or cutout device of the local control power
circuit must remain open when using a separate control
power source.
The preferred method for checking the control circuit is to
furnish a separate temporary source of control power of the
required control voltage rating. The temporary source must
have a properly coordinated backup protective device in the
circuit. Set the device to clear faults that might occur. Initially
all circuit breakers should be in the DISCONNECT position,
and the main circuit de-energized. When AC control power is
from control power transformers in the switchgear, remove
all fuses in the transformer circuits. On electrically operated
circuit breakers, discharge the springs; and the motor-
disconnect- switch should be in the OFF position.
5.
Rack drawout breakers to the DISCONNECT position.
6.
Open all normal control power source disconnects, if
supplied.
7.
Check each control switch or push-button.
Make sure that they are in the OPEN position.
8.
Connect a temporary control power source to the circuit
load terminals in the switchgear. Energize the control
circuit from the temporary control power source.
9.
Rack one circuit breaker into the TEST position. When
the on-off switch is in the ON position, the charging of
the closing springs of an electrically operated circuit
breaker indicates connection to the control power.
10.
Rack the remaining circuit breakers into the TEST
position, one at a time.
11.
Test all electrically and manually operated breakers for
closing and tripping, while they are in the TEST position.
Use the optional test set available with the trip unit for
testing solid state tripping.
12.
De-energize the control circuit. If AC control power is
from transformers in the switchgear, remove the
temporary separate source of control power.
Reinstall all fuses in the transformer circuit.
13.
Set all relays, regulators, and other devices for the
proper operation of loads. The factory does not set the
relays.
14.
Remove shorting screws from the terminal blocks in the
current transformer circuits. See Figure 22 on page 33.
Store screws in the tapped holes in the corners of the
blocks.
NOTE:
Verify the proper phasing of all main circuits
according to diagram.
60 HZ. RMS
WITHSTAND VOLTAGES
(PRIMARY CIRCUITS)
(1 MINUTE)
DC
WITHSTAND
*
Rated
voltage
240 V, 480 V,
600 V
Factory test
2200 volts
Field test
1650 volts
Field test
2300 volts
!
DANGER
!
DANGER
