Mitsubishi Electric FREQROL-CS80 Manual page 31

 Selecting the rated sensitivity current for the earth leakage circuit breaker
When using an 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
I∆n ≥ 10 × (Ig1 + Ign + Igi + Ig2 + Igm)
• Standard breaker
Rated sensitivity current
I∆n ≥ 10 × {Ig1 + Ign + Igi + 3 × (Ig2 + Igm)}
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 of
cable path per 1km during the
commercial power supply operation
when the CV cable is routed in
metal conduit
(200 V 60 Hz)
120
100
8 0
6 0
4 0
2 0
0
2 3.5 8 1422 38 80 150
5.5 30 60 100
2
Cable size (mm )
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 400 V 60 Hz)
120
100
8 0
6 0
4 0
2 0
0
2 3.5 81422 38 80 150
5.5 30 60 100
2
Cable size (mm )
For " " connection, the amount of leakage current is
appox. 1/3 of the above value.
Leakage current example of
three-phase induction motor
during the commercial
power supply operation
(200 V 60 Hz)
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)
Leakage current example of
threephase induction motor
during the commercial power
supply operation
(Totally-enclosed fan-cooled
type motor 400 V 60 Hz)
2.0
1.0
0.7
0.5
0.3
0.2
0.1
1.5 3.7 7.5 15223755
2.2 5.5 1 1 18.5 3045
Motor capacity (kW)
Example
2
2
5.5mm ×5m 5.5mm
ELB
Noise
filter
Inverter
Ig1 Ign
Igi
(Note) 1. Install the earth leakage circuit breaker (ELB) on the
input side of the inverter.
2. In the connection earthed-neutral system, the
sensitivity current is blunt against a 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 61140 class 1 and other applicable
standards)
●Selection example
Breaker designed
for harmonic and
surge suppression
Leakage current Ig1 (mA)
33 ×
Leakage current Ign (mA) 0 (without noise filter)
Leakage current Igi (mA) 1
Leakage current Ig2 (mA)
33 ×
Motor leakage current Igm
0.18
(mA)
Total leakage current (mA) 3.00
Rated sensitivity current
30
(mA) (≥ Ig × 10)
×50m
3φ
M
200V2.2kW
Ig2 Igm
Standard breaker
5m
= 0.17
1000m
50m
= 1.65
1000m
6.66
100
10
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