Table of Contents
4.4 Setting method of overcurrent tripping characteristics
1 250 A frame
OVER LED (red)
70% LED (green)
Over current operation test/
Characteristics setting connector
(1) Setting of current setting (Ir), instantaneous pickup current (Ii)
● Change the value with turning the operating characteristics selector.
Please use a flathead screwdriver show in the figure of lower right.
The appropriate a flathead is 3 mm in tip width and 0.5 mm in thickness.
Do not apply excessive force more than necessary. Doing so may cause breakdown.
(The appropriate operation torque is 0.05 N ･ m or less. ）
● Take out the label for current setting from the inside of the right side of circuit breaker.
And stick the label to the position under the handle.
Ir (Step adjustable)
Model name
Rated current In (A)
Current setting Ir (A)
Instantaneous pickup current Ii (A)
Underlined: Setting for shipment.
(2) Setting method except current setting and instantaneous pickup current
In the case of change the characteristics except current setting and instantaneous pickup current, change the setting with the operation check and
setup unit "Y-351" (option) or display unit of MDU breaker.
For setting using "Y-351", refer to the instruction manual for "Y-351".
For settings using the MDU breaker, refer to "7.1.1 Display method for protection characteristic setting values"
in INSTRUCTION MANUAL MDU BREAKER: MDU.
LTD time: TL
STD pickup current: Is
STD time: Ts
Ramp characteristics of LTD
Ramp characteristics of STD
Neutral pole protection: NP (Note 2)
Underlined: Setting for shipment.
Note 2) It can set only 4-pole circuit breaker.
Trip button
(Push to Trip)
NF250-SEV with MDU, NF250-HEV with MDU
250
Variable from 125 to 250 (variable in 12.5-A steps)
2-3-4-5-6-8-10-12-14 × Rated current In
A
14 × Current setting Ir
B
12-60-80-100 s (at 200% Ir)
2-2.5-3-3.5-4-5-6-7-8-9-10 × Ir
0.1-0.2-0.3 s
ON (I
t) – OFF (I
6
ON (I
t) – OFF (FLAT)
2
ON (function) – OFF (none)
≤ 0.05N ・ m
Ii (Step adjustable)
t)
2
6
Seal for current setting
Replacement label (Note 1)
Note 1)
If the current setting Ir or characteristics
of over current operation is changed,
please use the replacement label for indicate.
Operating characteristics selector
Ir
T
Ii
Ramp characteristics
of LTD
T
TL
Rlamp characteristics
of STD
I
Is
Ts
I
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