DESCRIPTION
As an alternative to derating an existing transformer, replacing it with a higher KVA unit or a K-Factor Rated Transformer, and increasing the capacity of the neutral bus, Harmonic Filters may be used to substantially reduce all single phase, non-linear load generated, Third Order, Harmonic Currents in the phase and neutral conductors of the three phase, four wire portion of the distribution system. In this type of harmonic environment, the various symptoms associated with Harmonic Currents will be reduced in both the three phase system and at the single phase loads.
This Power Quality improvement is accomplished by shunting the Harmonic Currents as close as possible to the point in the system where the single phase, non-linear loads are connected.
Harmonic Filters are UL Listed and CSA Certified, surpassing all the requirements of the NEMA, UL, ASA and CSA Standards. The units are manufactured with insulating materials which comply with CSA Winding Insulation System Class 220, the highest insulation level recognized by the transformer industry. Windings are available in either copper or aluminum. The units are available in standard, drip proof or weather proof enclosures.
APPLICATIONS
Harmonic Filters are highly suited for use in three phase, four wire electrical power distribution systems which supply single phase, non-linear loads. These loads include electronic lighting ballasts, computers, printers, and facsimile and copying machines which employ switchmode power supplies.
Harmonic Filters should be applied as close as possible to the offending loads, preferably at the furthest three-to- single phase point of distribution. This will insure maximum protection for the upstream system.
Harmonic Filters are available in a range of standard ratings, frequencies and voltages. The filter's rating is based on its continuous Neutral Current capacity. The required capacity of a filter can only be determined by calculating the available Harmonic Current at the point of its proposed connection. These calculations, which may be based on a measured harmonic profile or projected future maximum levels, must determine the impedances of all elements of the power system at each Harmonic Frequency and their load flows under all operating conditions. For distribution systems containing multiple panel sources of Harmonic Currents, calculations must be made to determine the required minimum number of filters, to optimize their location and to specify their ratings.
Harmonic Filters are available in all standard Power, Distribution and Drive Isolation Transformer ratings, frequencies and voltages, and with any angular displacement. In addition to their KVA rating, the units are also rated with respect to the power system's Harmonic Factor of Current (Hfi). A Hfi of 0.8 is standard. A suitable Hfi can be determined from a known or measured harmonic profile, from K-Factor rating calculations or from projected future maximum system levels.
SELECTION
The selection of a specific Harmonic Filter Type and Model must be based on the anticipated KVA requirements of the load, the Harmonic Profile of the Load Current, the Harmonic Factor of the Neutral Current, and the configuration of the existing or proposed system.
BENEFITS
Correctly applied in the three phase, four wire electrical power system, the Harmonic Filter will provide the following benefits:
For additional information on the Harmonic Filter and its application, please contact: