Mitsubishi Electric FR-A800 Instruction Manual page 70

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
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)}
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>
2 2
5.5mm 5m 5.5mm 60m
ELB
Noise
filter
Drive
unit
Ig1 Ign Ig2
Igi
• Inverter leakage current (with and without EMC filter)
Input power conditions (400 V class: 440 V/60 Hz, power supply unbalance within 3%)
Voltage
(V)
Phase
400
earthing
(grounding)
Earthed-neutral
system
400

Do not change the initially set ON (enabled) position of the EMC filter ON/OFF connector in the case of the inverter with a built-in C2 filter. The
Class C2 compatibility condition is not satisfied with the EMC filter OFF. The FR-A846-00250(7.5K)-C2 to FR-A846-00470(18.5K)-C2 are not
provided with the EMC filter ON/OFF connector. The EMC filter is always ON.

The inverter with a built-in C2 filter must be used in the earthed-neutral system.
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 400V60Hz)
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)
Item
Leakage current Ig1 (mA)
Leakage current Ign (mA)
Leakage current Igi (mA)
3φ
M
400V
2.2kW
Igm
Leakage current Ig2 (mA)
Motor leakage current Igm (mA)
Total leakage current (mA)
Rated sensitivity current (mA) (
EMC filter (C3) EMC filter (C2)
ON (mA) OFF (mA)
35 2
2 1
PRECAUTIONS FOR USE OF THE INVERTER
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
Breaker designed
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

≥
Ig 10) 30
ON (mA)

―

2
Standard breaker
5 m
= 0.11
1000 m
60 m
= 1.32
1000 m
6.15
100
69
3