Instruction manual

INSTALLATION AND WIRING
33
(
2
)
Selection 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, independent of the carrier frequency setting:
Rated sensitivity current:
l∆n ≥ 10 × {lg
1
+ lgn + 3 × (lg
2
+lgm)}
lg
1
, lg
2
: 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
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
Leakage current example
of 3-phase induction motor
during commercial power
supply operation
(200V 60Hz)
Leakage current (mA) Leakage current (mA)
Cable size (mm )
2
Motor capacity (kW)
Example of leakage current
per 1kW for commercial
power supply operation when
CV cable is routed in metal
conduit (200V 60Hz)
<Example>
NV
Ig1 Ign Ig2 Igm
5.5mm
2
×
5m
(16.40 feet)
5.5mm
2
×
70m
(229.66 feet)
IM
3
φ
200V 2.2kW (3HP)
Inverter
Noise
filter
5m (16.40 feet)
Leakage current Ig1 (mA)
33
×
1000m (3280.80 feet)
=
0.17
Leakage current Ign (mA)
0 (without noise filter)
70m (229.66 feet)
Leakage current Ig2 (mA)
33 ×
1000m (3280.80 feet)
=
2.31
Motor leakage current Igm (mA) 0.18
Total leakage current (mA) 7.64
Note 1. The earth leakage circuit breaker should
be installed to the primary (power
supply) side of the inverter.
2. Ground fault in the secondary side of the
inverter can be detected at the running
frequency of 120Hz or lower.
Reted sensitivity current
(
≥
Ig
×
10)
(mA)
100
3. If the connection neutral point ground fault in the inverter secondary side.
The protective ground resistance of the load equipment should be 10Ω or less.
4. When the breaker is grounded on the secondary side of the inverter, it may be unnecessarily
operated by harmonics if the effective value is less than the rating. In this case, note that the eddy
current and hysteresis loss increase and temperature rises.
* For the leakage current value of the noise filter installed on the inverter input side, contact the
corresponding filter manufacturer.