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INSTALLATION AND WIRING
38
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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:
• Progressive Super Series (Type SP, CF, SF,
CP)
Rated sensitivity current:
l
∆
n
≥
10
×
(lg1 + lgn + lg2 + lgm)
• Conventional NV series (Type CA, CS, SS
produced prior to '91)
Rated sensitivity current:
l
∆
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
0
20
40
60
80
100
120
23.5
5.5
81422
30
38
60
80
100
150
Example of leakage current per 1km
for commercial power supply operation
when CV cable is routed in metal conduit
(200V 60Hz)
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>
NV
Ig1 Ign Ig2 Igm
5.5mm
2
5m (16.40feet) 5.5mm
2
70m (16.40feet)
IM
3
200V 2.2kW (3HP)
Inverter
Noise
filter
Progressive Super
Series
(Type SP, CF, SF, CP)
Conventional NV
(Type CA, CS, SS)
5m (16.40feet)
Leakage current Ig1 (mA) 33
×
1000m (3280.80feet)
= 0.17
Leakage current Ign (mA) 0 (without noise filter)
70m (229.66feet)
Leakage current Ig2 (mA) 33
×
1000m (3280.80feet)
= 2.31
Motor leakage current Igm (mA) 0.18
Total leakage current (mA) 2.66 7.64
Note 1. The NV 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.
3. If the
connection neutral point ground
fault in the inverter secondary side.
The protective ground resistance of the
load equipment should be 10
Ω
or less.
Reted sensitivity current (mA)
(
≥
Ig
×
10)
30 100
4. When the breaker is installed 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, do not install it since
the eddy current and hysteresis loss increase and the temperature rises.
* Be careful of the leakage current value of the noise filter installed on the inverter input side.
2