YASKAWA G7 Series Technical Manual page 52

Countermeasures Against Radio Interference
Radio noise is generated from the Drive as well as from the input and output lines. To reduce radio noise,
install noise filters on both input and output sides, and also install the Drive in a totally enclosed steel box.
The cable between the Drive and the motor should be as short as possible.
Cable Length between Drive and Motor
If the cable between the Drive and the motor is long, the high-frequency leakage current will increase, causing
the Drive output current to increase as well. This may affect peripheral devices. To prevent this, adjust the
carrier frequency (set in C6-01, C6-02) as shown in Table 2.6. (For details, refer to Chapter 3 User
Parameters.)
Cable length
Carrier frequency
Ground Wiring
Observe the following precautions when wiring the ground line.
Always use the ground terminal of the 200-240 V Drive with a ground resistance of less than 100 Ω and
•
that of the 380-480 V Drive with a ground resistance of less than 10 Ω.
Do not share the ground wire with other devices, such as welding machines or power tools.
•
Always use a ground wire that complies with technical standards on electrical equipment and minimize the
•
length of the ground wire.
Leakage current flows through the Drive. Therefore, if the distance between the ground electrode and the
ground terminal is too long, potential on the ground terminal of the Drive will become unstable.
When using more than one Drive, be careful not to loop the ground wire.
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Steel box
Power
MCCB
supply
Noise
Drive
filter
Fig 2.10 Countermeasures Against Radio Interference
Table 2.6 Cable Length between Drive and Motor
50 m max. (164 ft)
15 kHz max.
OK
Fig 2.11 Ground Wiring
Metal pipe
Noise
IM
filter
100 m max. (328 ft) More than 100 m (> 328 ft)
10 kHz max.
NO
5 kHz max.