Mitsumi electronic FR-CV-7.5K to 30K(-AT) ユーザーズマニュアル

27

When using the earth leakage circuit breaker with the inverter circuit, select its rated sensitivity current as follows,
independent of the carrier frequency setting:
z Breaker for harmonic and surge 

Rated sensitivity current:
   l

Δn ≥ 10  × (lg

1

 + lgn + lg

2

 + lgm) 

z Standard breaker 

Rated sensitivity current: 
   l

Δn  ≥ 10  × {lg

1

 + lgn + 3 × (lg

2

+lgm)} 

   lg

1

, lg

2

: leakage currents of cable path during
  commercial power supply operation 

   lgn*

: leakage current of noise filter on power

regeneration common converter input
side 

   lgm

: leakage current of motor during 
  commercial power supply operation  

<Example>

* Be careful of the leakage current value of the noise filter installed on the power regeneration common

converter input side.

Leakage current Ig1 (mA)

50 

×  

=0.25 

Leakage current Ign (mA)

0 (without noise filter)

Leakage current Ig2 (mA)

50 

×  

=1.50 

Motor leakage current Igm (mA)

0.57

Total leakage current (mA)

2.32

6.46

Rated sensitivity current (mA) ( 

≥Ig × 10)

30

100

Note: 1. The NV should be installed to the primary (power supply) side of the power regeneration common

converter. 

2. Ground fault in the secondary side of the inverter can be detected at the running frequency of 120Hz or

lower. 

3. In the   connection neutral point grounded system, the sensitivity current becomes worse for ground

faults in the inverter secondary side. Hence, the protective grounding of the load equipment should be
10

Ω or less.

4. When the breaker is installed on the secondary side of the inverter, it may be unnecessarily operated by

harmonics if the effective value is less than the rating. In this case, do not install it since the eddy current
and hysteresis loss increase and the temperature rises.

5. The following models are standard breakers 

BV-C1, BC-V, NVB, NV-L, NV-G2N, NV-G3NA, and NV-2F type leakage current relays (except for
NV-ZHA), AA neutral wire, NV with open phase protection 

The following models are breakers for harmonic and surge 

NV-C/NV-S/MN series, NV30-FA, NV50-FA, BV-C2, leakage current alarm breaker(NF-Z), NV-ZHA,
NV-H

0

20

40

60

80

100

120

2 3.5

5.5

8 14 22

30

38

60

80

100

150

0.1

1.5

3.7

2.2

7.5 15 22

11

37

30

55

45

0.2

0.3

0.5

0.7

1.0

2.0

5.5

18.5

Example of leakage current 
per 1km in cable path during 
commercial power supply
operation when the CV 
cable is routed in metal 
conduit (200V 60Hz)

Leakage current example
of 3-phase induction motor
during commercial power
supply operation
(200V 60Hz)

Leak

age cu

rr

ent

 (

m

A

)

Leak

age cu

rr

ent

 (

m

A

)

Cable size (mm  )

2

Motor capacity (kW)

NV

Ig1

Ign

Ig2

Igm

IM

22mm

2

×5m

(16.40 feet)

22mm

2

×30m

(98.43 feet)

3φ
200V
15kW (20HP)

Noise
filter

+

Inverter

Power regeneration

common converter

15K

5m (16.40 feet)

1000m (3280.80 feet)

30m (98.43 feet)

1000m (3280.80 feet)