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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 
power line
 
Magnetic 
induction noise
 
Path  
<4>and<5>
Noise radiated from 
servomotor/spindle 
motor
 
Static induction 
noise
 
Path <6>
Cable propagation 
noise
 
Noise propagated over 
power 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>