Mitsubishi Electronics MR-J2S- A Leakage current breaker Selection method, Nv-Sf, Nv-Cf

13. OPTIONS AND AUXILIARY EQUIPMENT

13.2.7 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] ..........(13.2)

Cable

K: Constant considering the harmonic contents

Leakage current breaker

NV

Noise

Type

Mitsubishi

K

products

filter

Servo

Cable

SM

Models provided with

amplifier

NV-SF

1

harmonic and surge

NV-CF

reduction techniques

NV-CA

Ig1 Ign

Iga

Ig2

Igm

General models

NV-CS

3

NV-SS

Ig1:

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

of the servo amplifier (Found from Fig. 13.1.)

Ig2:

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

servo motor (Found from Fig. 13.1.)

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 13.6.)

Igm:

Leakage current of the servo motor (Found from Table 13.5.)

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

Table 13.5 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

Table 13.6 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

Table 13.7 Leakage circuit breaker selection example

	Rated sensitivity
Servo amplifier	current of leakage
	circuit breaker
MR-J2S-10A to MR-J2S-350A	15 [mA]
MR-J2S-10A1 to MR-J2S-40A1

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