Fuji Electric FRENIC-AQUA series User Manual page 30

Separating the grounding
Do not ground instruments and the inverter together. Noise may conduct through the grounding
wire. Use as a thick wire as possible for grounding.
Isolating the power supply
Noise may carry through the power supply line to instruments. It is recommended that the
distribution system be separated or a power isolation transformer (TRAFY) or noise suppression
transformer be used to isolate the power supply for such instruments from the power supply for
the inverter.
Adding inductance
Insert a chalk coil in series in the signal circuit, or pass the signal wiring through a ferrite core,
as shown in the figure below. This provides the wiring higher impedance against high-frequency
noise, and suppresses the propagation of high-frequency noise.
If an inductance is added, the signal waveform may become irregular and a
transmission error may result during communications at a high baud rate. In this
case, reduce the baud rate by changing the setting of function code y04.
[ 2 ] Measures against noise sources
Reducing carrier frequency
By lowering data of function code F26 "motor sound (carrier frequency)," the noise level can be
reduced. However, reducing the carrier frequency increases the motor sound.
Installing and wiring an inverter
Passing the power lines through metal conduit or adopting metal control panels can suppress
radiation or induction noise.
Isolating the power supply
Using a power isolation transformer on the line side of the inverter can cut off the propagation
(transmission) of noise.
[ 3 ] Additional measures to reduce the noise level
Consider using a zero-phase reactor or EMC compliance filter. The measures described in [1]
and [2] above can generally prevent noise. However, if the noise does not decrease to the
permissible level, consider additional measures to reduce the noise level. For details, see the
User's Manual of each inverter model. (Refer to the FRENIC-HVAC/AQUA User's Manual,
Chapter 4, Section 4.4.1.)
2-15
2.2 Connections