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(3) Selection of rated sensitivity current of earth leakage circuit 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:
I n
10
(Ig1 + Ign + Igi + Ig2 + Igm)
Standard breaker
Rated sensitivity current:
I n
10
{Ig1 + Ign + Igi + 3
Example
2
2
5.5mm
× 5m
5.5mm
ELB
Noise
filter
Inverter
Ig1
Ign
Ig2
Igi
Inverter leakage current (with and without EMC filter)
Input power conditions
(400V class: 440V/60Hz, power supply unbalance within 3%)
Phase
earthing
Earthed-neutral
system
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
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.
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
Ig2 + Igm)}
Selection example (in the case of the left figure (400V class
Leakage current Ig1 (mA)
× 60m
Leakage current Ign (mA)
IM
400V
2.2kW
Leakage current Igi (mA)
Igm
Leakage current Ig2 (mA)
Motor leakage current Igm (mA)
Total leakage current (mA)
Rated sensitivity current (mA)
* Refer to page 13 for the presence/absence of the EMC filter.
Voltage
(V)
400
400
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
1
66
3
Refer to the following table for the leakage current of the inverter*
1
66
3
2.79
30
EMC Filter
ON (mA)
OFF (mA)
30
1
1
1
earth
EMC and leakage currents
Leakage current example 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 1522
37
55
2. 2
5.5
11
18. 5
30
45
Motor capacity (kW)
connection))
Standard Breaker
5m
= 0.11
1000m
0 (without noise filter)
1 (without EMC filter)
60m
= 1.32
1000m
0.36
6.15
100
fault in the inverter output side.
3
Earthing
41

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