Mitsubishi Electronics MR-J2S- CL Leakage current breaker Selection method, Nv-Sw, Nfb

14. OPTIONS AND AUXILIARY EQUIPMENT

14.2.7 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 (11.8 in)) to minimize leakage currents.

Rated sensitivity current

10 {Ig1

Ign Iga

K (Ig2

Igm)} [mA] ..........(14.2)

Cable

K: Constant considering the harmonic contents

Leakage current breaker

K

NV

Noise

Type

Mitsubishi products

NV-SP

filter

Cable

Servo

SM

Models provided with

NV-SW

amplifier

1

harmonic and surge

NV-CP

reduction techniques

NV-CW

NV-HW

Ig1 Ign

Iga

Ig2

Igm

BV-C1

General models

NFB

3

NV-L

Ig1:

Leakage current on the electric channel from the leakage current breaker to the input terminals

of the servo amplifier (Found from Fig. 14.1.)

Ig2:

Leakage current on the electric channel from the output terminals of the servo amplifier to the

servo motor (Found from Fig. 14.1.)

Ign:

Leakage current when a filter is connected to the input side (4.4mA per one FR-BIF)

Iga:

Leakage current of the servo amplifier (Found from Table 14.5.)

Igm:

Leakage current of the servo motor (Found from Table 14.4.)

	120
current	100
	80
Leakage
	60
	40
[mA] 20
	0
		3.5	8 1422 38 80		150
	2
			5.5	30 60 100

Cable size[mm2]

Fig. 14.1 Leakage current example (Ig1, Ig2) for CV cable run in metal conduit

Table 14.4 Servo motor's leakage current example (Igm)

Servo motor	Leakage
output [kW]	current [mA]
0.05 to 0.5	0.1
0.6 to 1.0	0.1
1.2 to 2.2	0.2
3 to 3.5	0.3
5	0.5
7	0.7

Table 14.5 Servo amplifier's

		leakage current
		example (Iga)
Servo amplifier		Leakage
capacity [kW]		current [mA]
0.1 to 0.6		0.1
0.7 to 3.5		0.15
5	7	2
Table 14.6 Leakage circuit breaker selection example
	Servo amplifier		Rated sensitivity
			current of leakage
			circuit breaker [mA]
MR-J2S-10CLto MR-J2S-350CL			15
MR-J2S-10CL1 to MR-J2S-40CL1
MR-J2S-500CL			30
MR-J2S-700CL			50

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