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6. Installation
6 - 14
6-3 Noise measures
Noise includes "propagation noise" generated from the power supply or relay, etc., and propagated
along a cable causing the power supply unit or drive unit to malfunction, and "radiated noise"
propagated through air from a peripheral device, etc. causing the power supply unit or drive unit to
malfunction.
If the peripheral devices or units malfunction due to this noise, measures must be taken to suppress the
noise. The measures differ according to the noise propagation path, so refer to the following explanations
and take appropriate measures.
(1) General noise measures
Avoid laying the drive unit's power line and signal wire in a parallel or bundled state. Always
separate these wires. Use a twisted pair shielded wire for the detector cable and signal wires
such as the communication cable connected with the NC unit. Accurately ground the devices.
Use one-point grounding for the drive unit and motor.
Accurately ground the AC reactor.
(2) Propagation noise measures
Take the following measures when noise generating devices are installed and the power supply
unit or drive unit could malfunction.
Install a surge killer on devices (magnetic contactors, relays, etc.) which generate high levels of
noise.
Install a power supply filter.
Mount a ferrite core on the signal wire.
Ground the shield of the servo detector's cable with a cable clamp fittings.
(3) Measures against radiated noise
The types of propagation paths of the noise and the noise measures for each propagation path are
shown below.
Noise directly radiated
from drive unit
Airborne
propagation noise
Noise radiated from
p
owe
r
line
Magnetic
induction noise
Path
<4>and<5>
Noise radiated from
servomotor/spindle
moto
r
Static induction
noise
Path <6>
Cable propagation
noise
Noise propagated over
p
ower line
Noise generated
from drive unit
Path <1>
Path <2>
Path <3>
Path <7>
Noise lead in from
grounding wire by
leakage current
Path <8>