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EMC and leakage currents
(3) Selection of rated sensitivity current of earth leakage circuit breaker
When using the earth leakage circuit breaker with the inverter circuit, select its rated sensitivity current as follows,
independently of the PWM carrier frequency:
⋅ Breaker designed for harmonic and surge suppression
Rated sensitivity current:
IΔn ≥ 10 × (Ig1 + Ign + Igi + Ig2 + Igm)
⋅ Standard breaker
Rated sensitivity current:
IΔn ≥ 10 × {Ig1 + Ign + Igi + 3 × (Ig2 + Igm)}
Example of leakage current of
cable path per 1km during the
commercial power supply operation
when the CV cable is routed in
metal conduit
(200V 60Hz)
120
100
8 0
6 0
4 0
2 0
0
2 3.5
8 1422
38
80
5.5
30
60
Cable size (mm
<Example>
2
× 5m
2
5.5mm
5.5mm
ELB
Noise
filter
Inverter
Ig1
Ign
Ig2
Igi
CAUTION
⋅ Install the earth leakage circuit breaker (ELB) on the input side of the inverter.
⋅ In the
connection earthed-neutral system, the sensitivity current is blunt against an earth (ground) fault in the inverter output
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)
Use a neutral-point earthed (grounded) power supply for 400V class inverter in compliance with EN standard.
⋅ When the breaker is installed on the output 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 earth 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 leakage alarm breaker (NF-Z), NV-ZHA, NV-H
36
Leakage current example of
three-phase induction motor
during the commercial
power supply operation
(200V 60Hz)
2. 0
1. 0
0. 7
0. 5
0. 3
0. 2
0. 1
150
1. 5 3. 7
7. 5 1522
37
55
2. 2
5.5
11
18. 5
30
45
100
)
2
Motor capacity (kW)
Leakage current Ig1 (mA)
× 40m
Leakage current Ign (mA)
Leakage current Igi (mA)
IM
200V
5.5kW
Leakage current Ig2 (mA)
Igm
Motor leakage current Igm (mA)
Total leakage current (mA)
Rated sensitivity current (mA) (≥ Ig × 10)
Ig1, Ig2: Leakage currents in wire path during commercial
power supply operation
Ign: Leakage current of inverter input side noise filter
Igm: Leakage current of motor during commercial power
supply operation
Igi: Leakage current of inverter unit
Example of leakage current per 1km during
the commercial power supply operation
when the CV cable is routed in metal conduit
(Three-phase three-wire delta
connection 400V60Hz)
120
100
8 0
6 0
4 0
2 0
0
2 3.5
8 1422
38
80
150
5.5
30
60
100
Cable size (mm
2
)
For " " connection, the amount of leakage current is appox.1/3 of the above value.
Breaker Designed
for Harmonic and
Surge Suppression
33 ×
33 ×
Leakage current example of three-
phase induction motorduring the
commercial power supply operation
(Totally-enclosed fan-cooled
type motor 400V60Hz)
2. 0
1. 0
0. 7
0. 5
0. 3
0. 2
0. 1
1. 5 3. 7
7. 5 1522
37
2. 2
5.5
11
18. 5
30
Motor capacity (kW)
Standard Breaker
5m
1000m
0 (without noise filter)
1
40m
1000m
0.29
2.78
6.00
30
100
55
45
= 0.17
= 1.32

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