Mitsubishi Electric FR-A720-0.4K Instruction Manual page 65

(3) Selection of rated sensitivity current of earth (ground) leakage breaker
When using the earth (ground) 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 80 150
5.5 30 60 100
Cable size (mm 2 )
<Example>
2 × 5m 2 × 60m
5.5mm 5.5mm
ELB
Noise
filter
Inverter
Ig1 Ign Ig2
Igi
Inverter leakage current (with and without EMC filter)
Input power conditions
(200V class: 220V/60Hz, 400V class: 440V/60Hz, power supply unbalance within 3%)
Phase
grounding
Earthed-neutral
system
*For the FR-A720-0.4K and 0.75K, the EMC filter is always valid.
The leakage current is 1mA.
CAUTION
⋅ 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.
⋅ 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
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
1. 5 3. 7 7. 5 1522 37 55
2. 2 5.5 11 18. 5 30 45
Motor capacity (kW)
Leakage current Ig1 (mA)
Leakage current Ign (mA)
3φ
IM
400V
Leakage current Igi (mA)
2.2kW
Igm
Leakage current Ig2 (mA)
Motor leakage current Igm (mA)
Total leakage current (mA)
Rated sensitivity current (mA) (≥ Ig × 10)
* Refer to page 15 for the EMC filter.
Voltage
(V) ON (mA)
200
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
5.5 30 60 100
Cable size (mm
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
1
× 66 ×
3
EMC Filter
OFF (mA)
22(1)* 1
30 1
1 1
Noise and leakage currents
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
150 1. 5 3. 7 7. 5 1522 37
2. 2 5.5 11 18. 5 30
2 ) Motor capacity (kW)
Standard Breaker
5m
1000m
0 (without noise filter)
1 (without EMC filter)
current of the inverter*
60m
1000m
0.36
2.79 6.66
30 100
55
45
= 0.11
= 1.32
3
55