11 - 83
11. OPTIONS AND AUXILIARY EQUIPMENT
11.18 Leakage current breaker
(1) Selection method
High-frequency chopper currents controlled by p ulse width modulation flow in the AC servo circ uits.
Leakage currents containing harmonic contents are la rger 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 am plifier, servo
motor, etc. securely.
Make the input and output cables as short as possibl e, and also make the grounding cable as long as
possible (about 30cm) to minimize leakage c urrents.
Rated sensitivity current 10 {Ig1 Ign Iga K(Ig2 Igm)} [mA] (11 .1)
K: Constant considering the harmonic contents
Leakage current breaker
Type Mitsubishi
products
K
Models provided with
harmonic and surge
reduction techniques
NV-SP
NV-SW
NV-CP
NV-CW
NV-L
1
M
Servo
amplifier
Noise
filter
NV
I
g
1I
g
nI
g
aI
g
2I
g
m
Cable
Cable
General models
BV-C1
NFB
NV-L
3
Ig1: Leakage current on the electric channel from the leakage current breaker to the input terminals of t he
servo amplifier (Found from Fig. 11.3.)
Ig2: Leakage current on the electric channel from the output terminals of the ser vo amplifier to the
servo motor (Found from Fig. 11.3.)
Ign: Leakage current when a fi lter is connected to the input side (4.4mA per one FR-BIF(-H))
Iga: Leakage current of the ser vo amplifier (Found from Table 11.5.)
Igm: Leakage current of the servo motor (Found from Table 11.4.)
120
100
80
60
40
20
023.5
5.5
8 1422 3880 150
3060 100
Cable size[mm2]
[mA]
Leakage current
120
100
80
60
40
20
02
3.5
5.5
8
14
22
38
80
150
30
60
100
Cable size[mm2]
[mA]
Leakage current
a. 200V class b. 400V class
Fig. 11.3 Leakage current example (lg1, lg2) f or CV cable run in metal conduit