Service manual

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(2) Noise spread road
Fig.3-19 noise disturbance spread road sketch
(3) basic countermeasure for suppressing disturbance
Table 3-7 disturbance suppressing countermeasure table
Noise
spread
road
Countermeasure of weakening effect
①
When grounding wire of peripheral device and wiring of the inverter compose
closed-loop, inverter grounding wire leakage current would make the device do
wrong action. Can reduce wrong action if the device is not earthed here.
②
High-order harmonic from the inverter would make voltage and current transmit
through power supply wire when peripheral device and the inverter electrified by
same power supply, would disturb other devices in this same power supply system，
can take following suppressing measure: assemble electromagnetic noise filter at
inverter input end；isolate other devices by isolation transformer; connect power
supply for peripheral device with remote power source; install ferrite filter magnetic
circle for R, S, T three-phase conducting wire of the inverter to suppress conduction
of high-frequency harmonic current.
③④⑤
 Keep device and signal wire prone to disturbance from the inverter. Should
use shielded signal wire, shielding layer single end earthed and try best to keep away
from the inverter and its input, output wire. If signal wire must intersect strong power
cable, must keep them in real intersection and avoid parallel.
 Install high-frequency noise filter(ferrite common module choke, folksay
magnetic circle) separately at input, output root，which can effectively suppress
emission disturbance from dynamic wire.
 Should place motor cable shield of biggish thickness, for instance set it in tube
with biggish thickness (above 2mm) or bury it in cement slot. Dynamic wire set into
metal tube and use shielding wire to be grounded (use 4-core motor cable, one side is
earthed through the inverter, the other side connected to motor shell).
p
ower suppl
y
inverter
W
ireless set meter
motor
sensor
TV
①
⑦
⑧
⑥
⑤
③
②
②
⑤
④