App. A Advantageous Use of Inverters (Notes on electrical noise)
A-1
App. 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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