Omron SYSDRIVE 3G3JV Series User Manual page 34

Design
Countermeasures against Harmonics
With the continuing development of electronics, the generation of harmon-
ics from industrial machines has been causing problems recently.
The Ministry of International Trade and Industry provided some guidelines
in September 1994 for the suppression of harmonics from electrical house-
hold appliances and electrical equipment in Japan. Since then, the prob-
lem has been drawing considerable attention.
Refer to the following information for the definition of harmonics (i.e., har-
monic currents with voltages) and countermeasures against the genera-
tion of harmonics from the Inverter.
Harmonics
Definition
Harmonics consist of electric power produced from AC power and alternating at fre-
quencies that are integral multiples of the frequency of the AC power.
The following frequencies are harmonics of a 60- or 50-Hz commercial power supply.
Second harmonic: 120 (100) Hz
Third harmonic: 180 (150) Hz
Problems Caused by Harmonics Generation
The waveform of the commercial power supply will be distorted if the commercial power
supply contains excessive harmonics. Machines with such a commercial power supply
will malfunction or generate excessive heat.
2-26
Second harmonic (120 Hz)
Basic frequency (60 Hz)
Basic frequency (60 Hz) Third harmonic (180 Hz)
Distorted current wave
form
Third harmonic (180 Hz)
Chapter 2