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Installation and selection of the molded case circuit breaker
Install a molded case circuit breaker (MCCB) on the power receiving side to protect the wiring at the inverter input side. Select
an MCCB according to the inverter input side power factor, which depends on the power supply voltage, output frequency and
load. Especially for a completely electromagnetic MCCB, a slightly large capacity must be selected since its operation
characteristic varies with harmonic currents. (Check it in the data of the corresponding breaker.) As an earth leakage current
breaker, use the Mitsubishi earth leakage current breaker designed for harmonics and surge suppression.
Selecting the rated sensitivity current for the earth leakage circuit
breaker
To install the earth leakage circuit breaker on 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)}
• Selection example for the
Example
2
2
5.5 mm
5 m
5.5 mm
60 m
ELB
Noise
filter
Inverter
Ig1
Ign
Ig2
Igi
• Inverter/converter unit leakage current (mA)
FR-A800 (Standard
Inverter/converter unit
EMC filter
ON
Phase
35
earthing
(grounding)
Earthed-neutral
system
2
connection of the 400 V class
Leakage current Ig1 (mA)
Leakage current Ign (mA)
3φ
M
400 V
2.2 kW
Leakage current Igi (mA)
Igm
Leakage current Ig2 (mA)
Motor leakage current Igm (mA)
Total leakage current (mA)
Rated sensitivity current (mA) (≥ Ig
× 10)
FR-A802 (Separated
model)
converter type)
OFF
—
2
2
1
1
Ig1, Ig2: Leakage currents in wire path during commercial
power supply operation
Ign: Leakage current from noise filters on the input side of the
inverter
Igm: Leakage current from the 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 400 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
Cable size (mm
2
)
For " " connection, the amount of leakage current is appox. 1/3 of the above value.
Breaker designed
Item
for harmonic and
surge suppression
1
×
66 ×
3
0 (without noise filter)
1 (without EMC filter). For the leakage current
of the inverter, refer to the following table.
1
×
66 ×
3
0.36
2.79
30
Converter unit (FR-CC2)
ON
OFF
70
2
3. PRECAUTIONS FOR USE OF THE INVERTER
3.1 Electro-magnetic interference (EMI) and leakage currents
Leakage current example of three-
phase 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 1522
37
55
2. 2
5.5
11
18. 5
30
45
Motor capacity (kW)
Standard breaker
5m
= 0.11
1000m
60m
= 1.32
1000m
6.15
100
Remarks
2
Input power conditions
(440 V/60 Hz, power
supply imbalance within
3%)
1
1
2
3
4
5
6
7
8
9
10
77
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