Selecting The Rated Sensitivity Current For The Earth Leakage Circuit Breaker - Mitsubishi Electric FR-HC2-7.5K Instruction Manual

Precautions for selecting peripheral devices
1.3.3

Selecting the rated sensitivity current for the earth leakage circuit breaker

When using the earth leakage circuit breaker with the inverter circuit, select its rated sensitivity current as follows.
Breaker for harmonic and surge

Rated sensitivity current l
Standard breaker

Rated sensitivity current l
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
5.5mm 5.5mm
ELB
Noise
filter
Converter
lg1 lgn
NOTE
 Install the earth leakage circuit breaker (ELB) on the input side of the converter.
 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 with 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 the standard breakers
relay (except NV-ZHA), NV with AA neutral wire open-phase protection
The other models are designed for harmonic and surge suppression
C2, earth leakage alarm breaker (NF-Z), NV-ZHA, NV-H
14
  
+ + +
n 10 (lg1 lgn lg2 lg3
   {
+ + +
n 10 lg1 lgn lg2 3(lg3
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)
2 × 5m 2 × 70m
5.5mm
3φ
IM
Inverter
200V 2.2kW
lgm
lg2 lg3
lg1, lg2, lg3 : leakage current of cable path during
commercial power supply operation
+
lgm)
lgn : leakage current of noise filter on the
converter input side
+ }
lgm)
lgm : leakage currents of motor during commercial
power supply operation
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
5.5 30
Cable size (mm
For " " connection, the amount of leakage current is appox.1/3 of the above value.
Selection Example
(for the diagram shown on the left) (mA)
Leakage current lg1 (mA)
Leakage current lgn (mA)
Leakage current lg2 (mA)
Leakage current lg3 (mA)
Leakage current lgm (mA)
Total leakage current (mA)
Rated sensitivity current

( lg10)(mA)
....
BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, NV-2F earth leakage
....
NV-C/NV-S/MN series, NV30-FA, NV50-FA, BV-
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
80 150 1. 5 3. 7 7. 5 1522
60 100 2. 2 5.5 11
2 ) Motor capacity (kW)
Breaker for
harmonic
and surge
5m
33 
--------------- -
1000m
0 (without noise filter)
5m
33
--------------- -
1000m
70m
33
--------------- -
1000m
0.18
2.83
30
37 55
18. 5 30 45
Standard
breaker
=0.17
= 0.17
= 2.31
7.81
100