App. A Advantageous Use of Inverters (Notes on electrical noise)
A-1
App.
App.A Advantageous Use of Inverters (Notes on electrical
noise)
- Disclaimer: This document provides you with a summary of the Technical Document of the Japan Electrical
Manufacturers' Association (JEMA) (April 1994). It is intended to apply to the domestic market only. It is only for
reference for the foreign market. -
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
Phenomenon
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.)
Probable cause
Radios may receive noise radiated from the inverter.
Measures
Inserting a noise filter on the power supply side of the inverter is effective.
[ 2 ] Effect on telephones
Phenomenon
If an inverter operates, nearby telephones may pick up noise radiated from the
inverter in conversation so that it may be difficult to hear.
Probable cause
A high-frequency leakage current radiated from the inverter and motors enters
shielded telephone cables, causing noise.
Measures 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 proximity limit switches
Phenomenon
If an inverter operates, proximity limit switches (capacitance-type) may malfunction.
Probable cause
The capacitance-type proximity limit switches may provide inferior noise immunity.
Measures
It is effective to connect a filter to the input terminals of the inverter or change the
power supply treatment of the proximity limit switches. The proximity limit switches
can be replaced with superior noise immunity types such as magnetic types.
[ 4 ] Effect on pressure sensors
Phenomenon
If an inverter operates, pressure sensors may malfunction.
Probable cause
Noise may penetrate through a grounding wire into the signal line.
Measures
It is effective to install a noise filter on the power supply side of the inverter or to
change the wiring.
[ 5 ] Effect on position detectors (pulse generators PGs or pulse encoders)
Phenomenon
If an inverter operates, pulse encoders may produce erroneous pulses that shift the
stop position of a machine.
Probable 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.
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