14 - 74
14. OPTIONS AND AUXILIARY EQUIPMENT
14.15 Noise reduction techniques
Noises are classified into external noises which enter the servo amplifier to cause it to malfunction and those
radiated by the servo amplifier to cause per ipheral devices to malfunction. Since the s ervo amplifier is an
electronic device which handles small si gnals, the following general noise reduction t echniques are required.
Also, the servo amplifier can be a source of noise as its outputs are chopped by high carr ier frequencies. If
peripheral devices malfunction due to noises produced b y the servo amplifier, noise suppression measures
must be taken. The measures will vary slightl y with the routes of noise transmission.
(1) Noise reduction techniques
(a) General reduction techniques
Avoid laying power lines (input and output cables) and signal cables side by side or do not bundle
them together. Separate power lines from s ignal cables.
Use shielded, twisted pair cables for connecti on with the encoder and for control signal tra nsmission,
and connect the shield to the SD terminal.
Ground the servo amplifier, servo motor, etc. together at one point (refer to section 4.12).
(b) Reduction techniques for external noises that cause the servo amplifier to malfunc tion
If there are noise sources (such as a magnetic contactor, an electromagnetic brake, and m any relays
which make a large amount of noise) near th e servo amplifier and the servo amplifier may malfunction,
the following countermeasures are required.
Provide surge absorbers on the noise sourc es to suppress noises.
Attach data line filters to the signal cables.
Ground the shields of the encoder connecting cable and the control signal cables with cable clamp
fittings.
Although a surge absorber is built into the ser vo amplifier, to protect the servo amplifier an d other
equipment against large exogenous noise and lightning surge, att aching a varistor to the power input
section of the equipment is recommended.