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(3) Selection of rated sensitivity current of 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>
* Note the leakage current value of the noise filter installed on the inverter input side.
• Breaker designed for harmonic and surge
Rated sensitivity current
IΔn ≥10
× (Ig1 + lgn + Ig2 + Igm)
• Standard breaker
Rated sensitivity current
IΔn ≥10 × {Ig1 + Ign + 3 × (Ig2 + Igm)}
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
CAUTION
• Install the NV on the primary (power supply) side of the inverter.
• In the connection neutral point earthing (grounding) system, the sensitivity current is purified
against an earth (ground) fault in the inverter secondary side. Earthing (Grounding) must conform to
the requirements of national and local safety regulations and electrical codes. (NEC section 250, IEC
536 class 1 and other applicable standards)
• When the breaker is installed on the secondary side of the inverter, it may be unnecessarily operated
by harmonics even 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.
• The following models are standard breakers:
BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, and NV-2F type leakage current relays (except for NV-
ZHA), NV with AA neutral wire open phase protection
The following models are breakers for harmonic and surge suppression:
NV-C/NV-S/MN series, NV30-FA, NV50-FA, BV-C2, leakage current alarm breaker (NF-Z), NV-ZHA, NV-H
Breaker Designed for Harmonic and
Surge
Standard Breaker
Leakage current Ig1 (mA) 20 ×
5m
= 0.10
1000m
Leakage current Ign (mA) 0 (without noise filter)
Leakage current Ig2 (mA) 20 ×
70m
= 1.40
1000m
Motor leakage current Igm
(mA)
0.14
Total leakage current (mA) 1.66 4.78
Rated sensitivity current
(mA)
( ≥Ig × 10)
30 100
0
20
40
60
80
100
120
23.5
5.5
81422
30
38
60
80
100
150
Leakage Current Example of Cable
Path per 1km during 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 (mA)
Leakage Current Example of
three-Phase Induction Motor during
Commercial Power Supply Operation
(200V 60Hz)
Cable size (mm
2
) Motor capacity (kW)
Leakage current (mA)
NV
Ig1 Ign Ig2 Igm
IM
3
φ
200V1.5kW
Inverter
Noise
filter
2mm
2
70m
2mm
2
5m