Mitsubishi Electric FR-A500 Instruction Manual page 49

(2) Selection of the rated sensitivity current for the earth (ground) leakage circuit
breaker
When using the earth (ground) leakage circuit breaker with the inverter circuit, select its rated sensitivity
current as follows, independent of the carrier frequency setting:
• Breaker designed
suppression:
Rated sensitivity current:
l∆n ≥ 10 × (lg
+ lgn + lg
1
• Standard breakers:
Rated sensitivity current:
l∆n ≥ 10 × {lg
+ lgn + 3 ( (lg
1
1 2
lg , lg :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
* Be careful of the leakage current value of the noise filter installed on the inverter input side.
(Refer to the FR-A500 catalog for details of Mitsubishi inverter dedicated filter.)
<Example>
2
× 5m
5.5mm 5.5mm
(16.40 feet) (229.66 feet)
NV
Noise
filter
Inverter
Ig1
Ign
Note: 1. The NV should be installed to the
primary (power supply) side of the
inverter.
2. Earth (Ground) fault on the
secondary side of the inverter can
be detected at the running
frequency of 120Hz or lower.
3. In the connection neutral point earthing (grounding) system, the sensitivity current is purified
against an earth (ground) fault on the inverter secondary side. Earthing (grounding) must conform
to the requirements of national and local safety regulations and electrical codes. (JIS, NEC
section 250, IEC 536 class 1 and other applicable standards)
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 the
breaker since the eddy current and hysteresis loss will increase, leading to temperature rise.
5. General products indicate the following models:
BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, NV-2F, earth (ground) leakage relay (except NV-
ZHA), NV with AA neutral wire open-phase protection
The other models are designed for harmonic and surge suppression:
NV-C/NV-S/MN series, NV30-FA, NV50-FA, BV-C2, earth (ground) leakage alarm breaker (NF-Z),
NV-ZHA, NV-H
for harmonic and
+ lgm)
2
+lgm)}
2
2
× 70m
3 φ
IM
200V 2.2kW (3HP)
Ig2 Igm
INSTALLATION AND WIRING
surge
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
5.5
Cable size (mm )
Leakage current Ig1 (mA)
Leakage current Ign (mA)
Leakage current Ig2 (mA)
Motor leakage current Igm
(mA)
Total leakage current (mA)
Reted sensitivity current (mA)
≥
( Ig 10)
40
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
38 80 150 1.5 3.7
30 60 100 2.2
2
Motor capacity (kW)
Breaker designed for
harmonic and surge
suppression
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
7.5 15 22 37 55
5.5 11 18.5 30 45
Standard
breakers
= 0.17
= 2.31
7.64
100