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6.11
Earth-leakage current breaker
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 runs on AC power.
Select an earth-leakage current breaker according to the following formula, and ground the servo amplifier, servo motor, etc.
securely.
To minimize leakage currents, make the input and output wires as short as possible, and keep a distance of 30 cm or longer
between the wires and ground.
Rated sensitivity current ≥ 10 • {Ig1 + Ign + Iga + K • (Ig2 + Igm)} [mA] . . . (6.1)
Cable
Noise filter
NV
Servo
amplifier
Ig1
Ign
Iga
Earth-leakage current breaker
Type
Models provided with harmonic and surge reduction
techniques
General models
Ig1: Leakage current on the electric channel from the earth-leakage current breaker to the input terminals of the servo
amplifier
Page 95 Example of leakage current (Ig1, Ig2) per km of CV cable run in metal conduit
Ig2: Leakage current on the electric channel from the output terminals of the servo amplifier to the servo motor
Page 95 Example of leakage current (Ig1, Ig2) per km of CV cable run in metal conduit
Ign: Leakage current when a filter is connected to the input side (4.4 mA per FR-BIF(-H))
Iga: Servo amplifier leakage current
Page 96 Servo amplifier leakage current example (Iga)
Igm: Servo motor leakage current
Page 96 Servo motor leakage current example (Igm)
Example of leakage current (Ig1, Ig2) per km of CV cable run in metal conduit
• 200 V class
120
100
80
60
40
20
0
2
5.5 14
38 100
3.5
8
22
60 150
30
80
Wire size [mm²]
Cable
M
Ig2
Igm
Mitsubishi Electric products
NV-SP
NV-SW
NV-CP
NV-CW
NV-HW
BV-C1
NFB
NV-L
K
1
3
6 OPTIONS AND PERIPHERAL EQUIPMENT
6.11 Earth-leakage current breaker
6
95
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