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Peripheral Devices
(3) Selecting the rated sensitivity current for the earth (ground) leakage
breaker
When using the earth (ground) leakage breaker with the inverter circuit, select its rated
sensitivity current as follows, independently of the PWM carrier frequency.
<Example>
CAUTION
•On the power receiving side, install a no-fuse breaker (NFB) to protect the
primary wiring of the inverter. Selection of NFB depends on the power supply
side power factor (which changes with the power supply voltage, output
frequency and load) of the inverter. Especially as the completely
electromagnetic type NFB changes in operational characteristic with
harmonic currents, you need to choose the one of a little larger capacity. For
the earth (ground) leakage circuit breaker, use our product designed for
harmonic and surge suppression.
• Products designed for harmonic and surge suppression
Rated sensitivity current
In
≥
10
×
(lg1+Ign+lg2+lgm)
• General products
Rated sensitivity current
In
≥
10
×
{lg1+Ign+3
×
(lg2+lgm)}
Ig1, Ig2: Leakage currents of cable path during commercial power supply operation
Ign*: Leakage current of noise filter on inverter input side
Igm: Leakage current of motor during commercial power supply operation
0
20
40
60
80
100
120
23.5
5.5
81422
30
38
60
80
100
150
0.1
1.5 3.7
2.2
7.5 1522
11
37
30
55
45
0.2
0.3
0.5
0.7
1.0
2.0
5.5 18.5
Cable size (mm
2
)
Example of leakage current per 1km
in cable path during commercial
power supply operation when the
CV cable is routed in metal conduit
(200V 60Hz)
Leakage current (mA)
Leakage current example of
3-phase induction motor during
commercial power supply
operation (200V 60Hz)
Leakage current (mA)
Motor capacity (kW)
NV
Ig1 Ign Ig2 Igm
IM
Noise filter
Inverter
2mm
2
5m 2mm
2
70m
3
200V1.5kW