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(3)
Selection of rated sensitivity current of earth (ground) leakage current breaker
When using the earth leakage current 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
150
5.5
30
60
100
Cable size (mm
2
)
<
>
Example
2
2
5.5mm
5m
5.5mm
50m
Noise
ELB
filter
Inverter
Ig1
Ign
Ig2
Igi
NOTE
Install the earth leakage 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)
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.
General products indicate the following models. ...... BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, 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
Ig1, Ig2: Leakage currents in wire path during commercial
Ign:
Igm:
Igi:
Example of leakage current
of three-phase induction motor
during the commercial
power supply operation
(200V 60Hz)
1.0
0.7
0.5
0.3
0.2
0.1
0.07
0.05
0.03
0.02
20
0.1 0.2
0.75
2.2
5.5 11
0.4
1.5
3.7
7.5
15
Motor capacity (kW)
Leakage current Ig1 (mA)
Leakage current Ign (mA)
Leakage current Igi (mA)
3φ
IM
200V2.2kW
Leakage current Ig2 (mA)
Igm
Motor leakage current Igm (mA)
Total leakage current (mA)
Rated sensitivity current (mA)
(≥Ig × 10)
EMC and leakage currents
power supply operation
Leakage current of inverter input side noise filter
Leakage current of motor during commercial power
supply operation
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
3.00
30
Example of leakage current of three-
phase induction motor during 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
15
2.2
5.5
11
20
Motor capacity (kW)
Standard Breaker
5m
= 0.17
1000m
0 (without noise filter)
1
50m
= 1.65
1000m
0.18
6.66
100
3
33
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