Selecting The Rated Sensitivity Current For The Earth Leakage Current Breaker - Mitsubishi Electric FR-D700 Manual

Selecting the rated sensitivity current for the earth 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+3X(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
(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 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.
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
0.1 0.2 0.75 2.2 5.5 11 20
0.4 1.5 3.7 7.5 15
Motor capacity (kW)
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)
Example
2 2
× 5m × 60m
5.5mm 5.5mm
ELB
Noise
filter
Inverter
Ig1 Ign Ig2
Igi
(Note) 1 Install the earth leakage breaker (ELB) on the input side of the inverter.
2 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)
Selection example
(in the case of the above figure (400V class
Breaker Designed for
Harmonic and Surge
Suppression
1
Leakage current
× 66 ×
Ig1 (mA)
3
Leakage current
0 (without noise filter)
Ign (mA)
Leakage current Igi
(mA)
1
Leakage current
× 66 ×
Ig2 (mA)
3
Motor leakage
current Igm (mA)
Total leakage
2.79
current (mA)
Rated sensitivity
current (mA) (≥ Ig ×
30
10)
3φ
IM
400V
2.2kW
Igm
connection))
Standard Breaker
5m
= 0.11
1000m
1
60m
= 1.32
1000m
0.36
6.15
100
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