Mitsubishi FR-A500 Series Instruction Manual page 50

( 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 × (lg
+ lgn + lg
1
• Conventional NV series (Type CA, CS, SS
produced prior to '91)
Rated sensitivity current:
l∆n ≥ 10 × {lg + lgn + 3 × (lg
1
lg , lg : leakage currents of cable path
1 2
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
<Example>
×5m
2
5.5mm 5.5mm
(16.40 feet)
NV Noise
filter
Inverter
Ig1 Ign
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. In the connection neutral point
grounded system, the sensitivity current
becomes worse for ground faults in the
inverter secondary side. Hence, the
protective grounding of the load
equipment should be 10Ω or less.
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.
+ lgm)
2
+lgm)}
2
×70m
2
(229.66 feet)
3φ
IM
200V 2.2kW (3HP)
Ig2 Igm
INSTALLATION AND WIRING
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)
120
100
80
60
40
20
0
2 3.5 8 14 22 38
5.5 30 60
2
Cable size (mm )
Leakage current Ig1 (mA)
Leakage current Ign (mA)
Leakage current Ig2 (mA)
Motor leakage current Igm
(mA)
Total leakage current (mA)
(mA)
Reted sensitivity current
( ≥Ig × 10)
39
Leakage current example
of 3-phase induction motor
during commercial power
supply operation
(200V 60Hz)
2.0
1.0
0.7
0.5
0.3
0.2
0.1
80 150 1.5 3.7 7.5 15 22
100 2.2 5.5 11
Motor capacity (kW)
Progressive Super
Series Conventional NV
(Type SP, CF, SF, (Type CA, CS, SS)
CP)
5m (16.40 feet)
33 ×
1000m (3280.80 feet)
0 (without noise filter)
70m (229.66 feet)
33 ×
1000m (3280.80 feet)
0.18
2.66
30
37 55
18.5 30 45
= 0.17
= 2.31
7.64
100