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Main circuit terminals
(3) Selecting the rated sensitivity current for the earth leakage circuit
breaker
When using the earth leakage circuit breaker with the inverter circuit, select its rated
sensitivity current as follows, independently of the PWM carrier frequency:
• Breaker for harmonic and surge
Rated sensitivity current:
I
∆n ≥ 10 × (lg1+Ign+lg2+lgm)
• Standard breaker
Rated sensitivity current:
I
∆n ≥ 10 × {lg1+lgn+3 × (lg2+lgm)}
lg1, lg2 : Leakage currents of cable
path during commercial
power supply operation
lgn* : Leakage current of noise
filter on inverter input side
lgm : Leakage current of motor
during commercial power
supply operation
* Note the leakage current value of the
noise filter installed on the inverter
input side.
<Example>
Breaker for harmonic and
surge
Standard breaker
Leakage current (Ig1) (mA)
20 ×
5m
= 0.10
1000m
Leakage current (Ign) (mA) 0 (without noise filter)
Leakage current (Ig2) (mA)
20 ×
70m
= 1.40
1000m
Motor leakage
current (Igm) (mA)
0.16
Total leakage current (mA) 1.66 4.78
Rated sensitivity current
(mA) (≥ Ig
× 10)
30 100
Motor ca
p
acit
y
(
kW
)
Example of leakage
current per 1km in cable
path during commercial
power supply operation
when the CV cable is
routed in metal conduit
Leakage current (mA)
Leakage current (mA)
Cable size (mm)
2
Leakage current
example of three-phase
induction motor
during commercial
power supply
operation
(200V 60Hz)
(200V 60Hz)
0
20
40
60
80
100
120
2 3.5 814223880
5.5 3060100
150
1.5 3.7
2.2
7.5 152 2
11
37
30
55
45
5.5 18.5
2.0
1.0
0.7
0.5
0.3
0.2
0.1
NV
Ig1 Ign Ig2 Igm
2mm ×5m
2mm ×70m
IM
3
200V
1.5kW
Inver-
ter
Noise
filter
22