User`s manual

22
Wiring Chapter 2-2
Countermeasures against
Induction Noise
As described previously, a Noise Filter can be used to prevent induction noise
from being generated on the output side. Alternatively, cables can be routed
through a grounded metal pipe to prevent induction noise. Keeping the metal
pipe at least 30 cm away from the signal line considerably reduces induction
noise.
Countermeasures against
Radio Interference
Radio noise is generated from the Inverter as well as the input and output
lines. To reduce radio noise, install Noise Filters on both input and output
sides, and also install the Inverter in a totally enclosed steel box.
The cable between the Inverter and the motor should be as short as possible.
Cable Length between
Inverter and Motor
As the cable length between the Inverter and the motor is increased, the
floating capacity between the Inverter outputs and the ground is increased
proportionally. The increase in floating capacity at the Inverter outputs causes
the high-frequency leakage current to increase, and this may adversely affect
peripheral devices and the current detector in the Inverter’s output section. To
prevent this from occurring, use a cable of no more than 100 meters between
the Inverter and the motor. If the cable must be longer than 100 meters, take
measures to reduce the floating capacity by not wiring in metallic ducts, by
using separate cables for each phase, etc.
Also, adjust the carrier frequency (set in n46) according to the cable length
between the Inverter and the motor, as shown in the following table.
Note Single-phase motors cannot be used.
The Inverter is not suited for the variable speed control of single-phase
motors.
The rotation direction of a single-phase motor is determined by the capacitor
starting method or phase-splitting starting method to be applied when starting
the motor.
In the capacitor starting method, however, the capacitor may be damaged by
a sudden electric discharge of the capacitor caused by the output of the
Inverter. On the other hand, the starting coil may burn in the phase-splitting
starting method because the centrifugal switch does not operate.
Power supply
CIMR-J7AZ
VARISPEED
Signal line
Controller
MCCB
Metal pipe
30 cm min.
Power supply
MCCB
Noise
Filter
VARISPEED
Noise
Filter
CIMR-J7AZ
Steel box
Metal pipe
Cable length 50 m or less 100 m or less More than 100 m
Carrier frequency 10 kHz max. 5 kHz max. 2.5 kHz