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6
SUPPLEMENT
.
6. SUPPLEMENT
6.1 Reasons why the shield is grounded on both the cabinet side and the servo motor chassis side
As for a countermeasure against radiated emissions from inverters or servo amplifiers, multiple point grounding,
in which grounding is performed at the cabinet exit and both ends of the cable between the servo amplifier and
the servo motor, tends to decrease unnecessary noise.
6.1.1 Grounding the shield at the servo amplifier side only
The following figure shows only wiring of the servo motor power cable. Use a shielded wire for the detector
cable as well as the power cable.
Figure 6.2 shows one of measurement result examples. It does not guarantee the effect of the countermeasure.
LIMIT: IEC/EN 61800-3 (10 m)
[dBuV/m]
100
90
80
70
60
50
40
30
20
10
0
30
Fig. 6.2 Radiated emissions of when the cable between the servo amplifier
Cabinet
Grounding
10 cm or less
To servo
amplifier
When a shielded wire is used
Fig. 6.1 When the cable between the servo amplifier and servo motor
is grounded on the servo amplifier side only
50
70
and servo motor is grounded on the servo amplifier side
6 - 1
Connector
Connect the shield part or earth
wire coming out outside the
cabinet with the earth terminal
of the connector at the servo
motor side.
Servo motor
Shielded cable
100
Servo motor
U
Motor
V
M
W
Shield
×: Ver. (QP)
○: Hor. (QP)
HORIZONTAL/VERTICAL
200
300
Frequency
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