Mitsubishi Electronics FR-A701 ユーザーズマニュアル

EMC and leakage currents

(3) Selection of rated sensitivity current of earth leakage circuit breaker

When using the 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

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

Breaker Designed

for Harmonic and

Surge Suppression

Standard Breaker

Leakage current Ig1 (mA)

= 0.17

1000m

Leakage current Ign (mA)

0 (without noise filter)

Leakage current Igi (mA)

Leakage current Ig2 (mA)

40m

= 1.32

1000m

Motor leakage current Igm (mA)

0.29

Total leakage current (mA)

2.78

6.00

Rated sensitivity current (mA)

(≥ Ig × 10)

100

CAUTION

⋅ Install the earth leakage circuit 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)
Use a neutral-point earthed (grounded) power supply for 400V class inverter in compliance with EN standard.

⋅ 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)

1. 5 3. 7

2. 2

7. 5 1522

5.5

18. 5

0. 1

0. 2

0. 3

0. 5

0. 7

1. 0

2. 0

2 0

4 0

6 0

8 0

100

120

2 3.5

5.5

8 1422

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)

Cable size (mm

)

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)

2 0

4 0

6 0

8 0

100

120

leakage currents (mA)