Mitsubishi Electric C Series Handling And Maintenance page 78

3 LTD and pre-alarm operating time can be checked by applying a current equivalent to 200% of
the current setting Ir. If however any current exceeding the current setting Ir is applied before
this test, the operating time reduces. Therefore the first measurement will be invalid in that
case. When the circuit-breaker trips, the trip circuit is reset, and the next operating time can be
measured under normal conditions.
200% of the current setting Ir
The result is good if the operating time measured falls within the following range: (Ampere frame 100~250)
Setting of LTD time T
L
Pre-alarm operating time
LTD operating time
The result is good if the operating time measured falls within the following range: (Ampere frame 400~800)
Setting of LTD time T
L
Pre-alarm operating time
LTD operating time
(4) Overcurrent trip test (2)
CAUTION
Connector (JST make)
(
Housing: H3P-SHF-AA
Contacts: BHF-001T-0. 8BS
Connector
3 2 1
Power
Power supply supply
switch
(24VDC)
Push-button switch
Instantaneous action
check button
Power supply
switch
Battery check button
Breaker tester "Y-150"
6 Tighten the transparent cover with 0.3 to 0.6 N·m of tightening torque, and stick the stamped
seal on the tightening screw.
7 Though the overcurrent display LED goes off and the trip coil remains tripped if the test is
carried out with the circuit-breaker OFF, the circuit-breaker handle remains unchanged (OFF).
If application is made under this state, the handle will idle. The test should therefore be per-
formed with the circuit-breaker ON without fail.
70% LED (Green)
PAL LED (Yellow)
Pre-alarm operating time
OVER LED (Red)
T =12sec T =60sec
L L
4.8~7.2s 24~36s
9.6~14.4s 48~72s
T =12sec T =60sec
L L
4.8~7.2s 24~36s
9.6~14.4s 48~72s
Applicable type: NF1000-SS NF1250-SS NF1600-SS
Perform the test under the condi-
tion that the circuit-breaker is ON
and the load current does not flow.
1 Prepare the external
)
power supply (24
VDC) and switches
or optional breaker
tester "Y-150".
2 Strip off the stamped
seal, loosen the
transparent cover
attaching screws
under this seal, and
wire the connector
to the test terminal.
3 Long time delay test.
(a) When the power supply switch is turned ON, the test signal comes
on enabling the long time delay.
(b) The test signal has been so designed that about 200% of the maxi-
mum rated current produces. The operating time depends upon the
setting of the rated current.
4 Instantaneous tripping test
The instantaneous trip happens when the power supply switch and push-
button (instantaneous action check button in case of tester) are turned
ON.
5 When the test is over, a stamped seal shall be taken out of the seals for
replacement.
Continuous
lighting starts
LTD time
T =80sec T =100sec
L L
32~48s 40~60s
64~96s 80~120s
T =100sec T =150sec
L L
40~60s 60~90s
80~120s 120~180s
NF1250-UR
NF2000-PAL
Table of LTD test operating time (sec)
Ampere
frame
500A
1000
15-37
600A
1250
14-34
800A
1600
15-37
1200A
2000
22-54
trip
SETTING POSITION
1 2 3 4
600A 700A 800A
22-54 29-73 38-96
700A 800A 1000A
19-46 24-60 38-96
1000A 1200A 1400A
23-59 34-64 46-115
1400A 1500A 1600A
29-73 34-84 38-96
5 6
900A 1000A
49-112 60-150
1200A 1250A
54-136 60-150
1500A 1600A
52-130 60-150
1800A 2000A
49-122 60-150
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