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11. OPTIONS AND AUXILIARY EQUIPMENT
11.6 Noise reduction techniques
Noises are classified into external noises which enter the driver to cause it to malfunction and those radiated by
the driver to cause peripheral devices to malfunction. Since the driver is an electronic device which handles
small signals, the following general noise reduction techniques are required.
Also, the driver 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 driver, 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 driver, servo motor, etc. together at one point (refer to section 3.12).
(b) Reduction techniques for external noises that cause the driver to malfunction
If there are noise sources (such as a magnetic contactor, a lock, and many relays which make a large
amount of noise) near the driver and the driver 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 driver, to protect the driver and other equipment against
large exogenous noise and lightning surge, attaching a varistor to the power input section of the
equipment is recommended.
(c) Techniques for noises radiated by the driver that cause peripheral devices to malfunction
Noises produced by the driver are classified into those radiated from the cables connected to the driver
and its main circuits (input and output circuits), those induced electromagnetically or statically by the
signal cables of the peripheral devices located near the main circuit cables, and those transmitted
through the power supply cables.
Noise transmitted through power supply cable
Noise radiated directly from servo amplifier
Noise radiated from the power supply cable
Noise radiated from servo motor cable
Noise sneaking from grounding cable due
to leakage current
Noises transmitted
in the air
Noises produced
by servo amplifier
Static induction
noise
Magnetic induction
noise
Noises transmitted
through electric
channels
Route 1)
Route 2)
Route 3)
Route 4) and 5)
Route 6)
Route 7)
Route 8)
driver
driver