Mitsubishi Electronics FR-A720-0.4k to 90k User Manual

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:

<Example>

z

z

Input power conditions

(200V class: 220V/60Hz, 400V class: 440V/60Hz, power supply unbalance within 3%)

⋅ Breaker designed for harmonic and surge suppression

Rated sensitivity current: 

I

Δn ≥ 10 × (Ig1 + Ign + Igi + Ig2 + Igm)

⋅ Standard breaker

Rated sensitivity current: 

I

Δn ≥ 10 × {Ig1 + Ign + Igi + 3 × (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

Leakage current Ig1 (mA)

 

×

 

66 

×

5m

= 0.11

1000m

Leakage current Ign (mA)

0 (without noise filter)

Leakage current Igi (mA)

1 (without EMC filter)

Refer to the following table for the leakage 

current of the inverter*

Leakage current Ig2 (mA)

 

×

 

66 

×

60m

= 1.32

1000m

Motor leakage current Igm (mA)

0.36

Total leakage current (mA)

2.79

6.15

Rated sensitivity current (mA) 

(≥ Ig × 10)

30

100

* Refer to page 15 for the EMC filter.

22(1)*

1

30

1

1

1

*For the FR-A720-0.4K and 0.75K, the EMC filter is always valid.

The leakage current is 1mA.

⋅ 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

(200V  60Hz)

(200V  60Hz)

1. 5 3. 7

2. 2

7. 5 1522

11

37

30

55

45

5.5

18. 5

0. 1

0. 2

0. 3

0. 5

0. 7

1. 0

2. 0

0

2 0

4 0

6 0

8 0

100

120

2 3.5

5.5

8 1422

30

38

60

80

100

150

Motor capacity (kW)

Example of leakage current of
cable path per 1km during the
commercial power supply operation
when the CV cable is routed in 
metal conduit

Leakage current example of
three-phase induction motor
during the commercial
power supply operation

Leakage currents (mA)

Leakage currents (mA)

Cable size (mm

2

)

Motor capacity (kW)

For "   " connection, the amount of leakage current is appox.1/3 of the above value.

(Three-phase three-wire delta
 connection 400V60Hz)

Example of leakage current per 1km during 
the commercial power supply operation 
when the CV cable is routed in metal conduit

Leakage current example of three-
phase induction motor during the 
commercial power supply operation

(Totally-enclosed fan-cooled
 type motor 400V60Hz)

0

2 0

4 0

6 0

8 0

100

120

leakage currents (mA)

leakage currents (mA)

2 3.5

5.5

8 1422

30

38

60

80

100

150

Cable size (mm

2

)

0. 1

0. 2

0. 3

0. 5

0. 7

1. 0

2. 0

1. 5 3. 7

2. 2

7. 5 1522

11

37

30

55

45

5.5

18. 5

Noise 

filter

Inverter

ELB

Ig1

Ign

Igi

Ig2

Igm

IM

5.5mm

2 

×

 

5m

5.5mm

2  

×

 

60m

400V

2.2kW

3

φ

1
3

1
3

Phase 
grounding

Earthed-neutral 
system