Harmonics can be "trapped" by the application of a Myron Zucker, Inc. tuned filter trap. The trap is an inductor-capacitor (LC) filter which provides a low-impedance path for the harmonic currents. It "traps" the harmonics between itself and the harmonic source. As in correcting power factor problems at the source with capacitors, Myron Zucker, Inc. also recommends correcting harmonics problems at the source by using traps. For that reason, Myron Zucker, Inc. manufactures Caltrap™ brand harmonic filters from 10 to 100 kVAR, commonly tuned to the 5th harmonic, although other points are available. Myron Zucker, Inc. can also provide Caltrap™ brand harmonic filters with an integral line reactor to further isolate harmonics and provide other line reactor benefits such as reduced voltage notching from ASDs. Typical installations are shown in Figures 5 and 6 below.

Although the best engineering practice is to trap the harmonics at the source, for economic reasons it may be better to use one trap for several harmonic sources. For example, a machine with several ASDs could be corrected with one trap at the machine control panel. In the same way, several small ASDs fed from one bus duct could have a trap at the beginning of the bus duct, giving the rest of the system better power quality.

In some cases, an even larger trap can be provided at the switchgear, feeding an entire low-voltage system. This would still trap the harmonics before the service transformer and could be used to reduce utility voltage harmonics.

Myron Zucker, Inc. manufactures Capacitrap® brand harmonic filters and automatically controlled Autocapacitrap™ brand harmonic brand harmonic filters for these applications. Your local representative or Myron Zucker, Inc.'s Application Engineering Department can help determine what products are best for any application.

Myron Zucker, Inc. has successfully installed Caltrap™, Capacitrap® and Autocapacitrap™ brand harmonic filters throughout the US and other countries. Our quality products and over 50 years of experience in the power industry can be beneficial in any application.