10
PERIPHERAL DEVICE
10-10
10-5) Power filter
In the servo amplifier, the pulse width modulation circuit performs high frequency switching similarly to
general-purpose inverters. This causes power line noise, radiation noise from the amplifier and noise
from the motor power cable, and these noises may have an adverse influence over external equipment.
To prevent such an influence, the following methods are available.
(1) House the servo amplifier in a steel container (control cabinet) and ground the container. Avoid
installation in a place close to the PC or measuring instruments.
(2) If the amplifier affects the equipment of which power is shared with the amplifier, incorporate the
power filter in the primary circuit of the servo amplifier.
If the amplifier affects the equipment which gets its drive from different power source, install the
transformer for radio noise prevention (TRAFY).
(3) Use a metal conduit to house the cable extended from the servo amplifier to the servomotor, and
ground the conduit (grounding at several points is possible).
(4) Use a thick cable for grounding and make the cable as short as possible. Connect the grounding cable
from the individual equipment directly to a copper bar (do not ground via any equipment).
(5) Avoid mutual connection of the following signals.
(6) Avoid binding together the main circuit and control circuit or laying them in parallel.
Main circuit : Commercial power supply, motor power cable between servo amplifier and
servomotor
Control circuit : Analog voltage cable, +24VDC or +15VDC level signal cables, encoder cables of
servomotor
(7) Connect a transformer for radio noise prevention (TRAFY) to separate 100V power system devices
(PLC, general-purpose PC, etc.) from the 200V power system.
Power
supply
Servo amplifier
Ｍ
Servomotor
Measuring
instrument
Electronic
device
Sensor
Power line noise
Power transformer
Radio
Radiation noise
Electromagnetic
induced noise
Electrostatic
induced noise
Grounding terminal
and frame
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