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12. OPTIONS AND AUXILIARY EQUIPMENT
12.18 Leakage current breaker
(1) Selection method
High-frequency chopper currents controlled by pulse width modulation flow in the AC servo circuits.
Leakage currents containing harmonic contents are larger than those of the motor which is run with a
commercial power supply.
Select a leakage current breaker according to the following formula, and ground the servo amplifier, servo
motor, etc. securely.
Make the input and output cables as short as possible, and also make the grounding cable as long as
possible (about 30cm) to minimize leakage currents.
Rated sensitivity current
10 {Ig1 Ign Iga K (Ig2 Igm)} [mA] .................................................... (12.1)
Ign
Noise filter
Cable
Ig1 Iga Ig2 Igm
M
Servo
amplifier
NV
Cable
K: Constant considering the harmonic contents
Leakage current breaker
K
Type
Mitsubishi
products
Models provided with
harmonic and surge
reduction techniques
NV-SP
NV-SW
NV-CP
NV-CW
NV-L
1
General models
BV-C1
NFB
NV-L
3
Ig1
Ig2
Ign
Iga
Igm
: Leakage current on the electric channel from the leakage current breaker to the input terminals of the
servo amplifier (Found from Fig. 12.3.)
: Leakage current on the electric channel from the output terminals of the servo amplifier to the servo
motor (Found from Fig. 12.3.)
: Leakage current when a filter is connected to the input side (4.4mA per one FR-BIF-(H))
: Leakage current of the servo amplifier (Found from Table 12.5.)
: Leakage current of the servo motor (Found from Table 12.4.)
120
100
80
60
40
20
0
23.5
5.5
814223880150
3060 100
[mA]
L
e
a
k
a
g
e
c
u
r
r
e
n
t
120
100
80
60
40
20
0
2
3.5
5.5
8
14
22
38
80
150
30
60
100
[mA]
L
e
a
k
a
g
e
c
u
r
r
e
n
t
Fig. 12.3 Leakage current example (Ig1, Ig2) for CV cable run in metal conduit
Cable size [mm
2
]
a. 200V class
Cable size [mm
2
]
b. 400V class