Yaskawa Varispeed-686SS5 CIMR-SSA - Manual (Page 27)

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(h) Using Output Noise Filters
By installing a noise filter on the output side of the inverter, radio frequency interference
(RFI) and inductive noise are reduced.
M
MCCB
VS-686SS5
Power
Supply
Noise
Filter
RFI Noise
AM Radio
Inductive
Noise
Signal Line
Control
Device
Fig. 12 Using Output Noise Filter
Inductive noise: Noise coming on the signal line due to electromagnetic inductance can
cause malfunctioning of a control device.
RFI noise: Higher harmonics waves from the inverter or cable can interfere with radio
receiver.
(i) Countermeasures Against Inductive Noise
As described previously, a noise filter can be used to prevent inductive noise from generated
on the output side. Alternatively, cables can be routed through a grounded metal pipe to
prevent inductive noise. Keeping the metal pipe at least 30 cm away from the signal line
considerably reduces inductive noise.
M
MCCB
VS-686SS5
Power
Supply
Signal Line
Control
Device
Metal Pipe
30 cm min.
Fig. 13 Countermeasures Against Inductive Noise
(j) Countermeasures Against RFI Noise
RFI noise is generated form the inverter as well as from the input and output lines. To reduce
RFI noise, install noise filters on both input and output sides, and also install in a totally en-
closed steel box. The cable between the inverter and the motor should be as short as pos-
sible.
M
MCCB
VS-686SS5
Power
Supply
Metal Pipe
Noise
Filter
Noise
Filter
Steel Box
Fig. 14 Countermeasures Against RFI Noise