App. A Advantageous Use of Inverters (Notes on Electrical Noise)
A-1
App.
App. A Advantageous Use of Inverters (Notes on Electrical Noise)
This document provides you with a summary of the Technical Document of
the Japan Electrical Manufacturers' Association (JEMA) (December, 2008).
A.1 Effect of inverters on other devices
Inverters have been and are rapidly expanding its application fields. This paper describes the effect that
inverters have on electronic devices already installed or on devices installed in the same system as
inverters, as well as introducing noise prevention measures. (Refer to Section A.3 [3], "Noise prevention
examples" for details.)
[1] Effect on AM radios
Problem
If an inverter operates, AM radios may pick up noise radiated from the inverter. (An
inverter has almost no effect on FM radios or television sets.)
Possible cause
Radios may receive noise radiated from the inverter.
Measure Inserting a noise filter on the power supply side of the inverter is effective.
[2] Effect on telephones
Problem
If an inverter operates, nearby telephones may pick up noise radiated from the inverter in
conversation so that it may be difficult to hear.
Possible cause A high-frequency leakage current radiated from the inverter and motors enters shielded
telephone cables, causing noise.
Measure
It is effective to commonly connect the grounding terminals of the motors and return the
common grounding line to the grounding terminal of the inverter.
[3] Effect on pressure sensors
Problem
If an inverter operates, pressure sensors may malfunction.
Possible cause Noise may penetrate through a grounding wire into the signal line.
Measure
It is effective to install a noise filter on the power supply side of the inverter or to separate
the input and output wires or grounding wires from the control circuit.
[4] Effect on position detectors (pulse generators)
Problem
If an inverter operates, pulse encoders may produce erroneous pulses that shift the stop
position of a machine.
Possible cause
Erroneous pulses are liable to occur when the signal lines of the PG and power lines are
bundled together.
Measure
The influence of induction noise and radiation noise can be reduced by separating the PG
signal lines and power lines. Providing noise filters at the input and output terminals is
also an effective measure.
[5] Effect on proximity switches
Problem
If an inverter operates, proximity switches (capacitance-type) may malfunction.
Possible cause
The capacitance-type proximity switches may provide inferior noise immunity.
Measure
It is effective to connect a filter to the input terminals of the inverter or to ground at the
0V-side capacitor of the power supply of the proximity switches. The proximity switches
can be replaced with superior noise immunity types such as magnetic types.
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