MITSUBISHI ELECTRIC Merservo MR-J2S- B - Manual (Page 211)

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12. OPTIONS AND AUXILIARY EQUIPMENT
12.2.7 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 peripheral devices to malfunction. Since the servo amplifier
is an electronic device which handles small signals, the following general noise reduction techniques are
required.
Also, the servo amplifier can be a source of noise as its outputs are chopped by high carrier frequencies. If
peripheral devices malfunction due to noises produced by the servo amplifier, noise suppression measures
must be taken. The measures will vary slightly 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 signal cables.
Use shielded, twisted pair cables for connection with the encoder and for control signal
transmission, and connect the shield to the SD terminal.
Ground the servo amplifier, servo motor, etc. together at one point (refer to section 3.9).
(b) Reduction techniques for external noises that cause the servo amplifier to malfunction
If there are noise sources (such as a magnetic contactor, an electromagnetic brake, and many
relays which make a large amount of noise) near the servo amplifier and the servo amplifier may
malfunction, the following countermeasures are required.
Provide surge absorbers on the noise sources 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 servo amplifier, to protect the servo amplifier and
other equipment against large exogenous noise and lightning surge, attaching a varistor to the
power input section of the equipment is recommended.