Myron Zucker, Inc. FAQ
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 FAQ Categories Resources > FAQ 1. What are harmonics? Harmonics are multiples of the fundamental frequency distortions found in electrical power, subjected to continuous disturbances. In a 60 Hz electrical system 350 Hz is the 5th harmonic, 420 Hz is the 7th harmonic, and so on. Harmonics are created by the use of non-linear devices such as UPS systems, solid state variable speed motor drives, rectifiers, welders, arc furnaces, fluorescent ballasts and personal computers. Individual harmonic frequencies will vary in amplitude and phase angle, depending on the harmonic source. Top of Page 2. What are some indications of harmonic resonance? Some indications are overheating, frequent circuit breaker tripping, unexplained fuse operation, capacitor failures, electronic equipment malfunction, flicking lights and telephone interference, insulation melting off of conductors (skin effect). Top of Page 3. How to solve harmonic resonance? The solution can be accomplished by: 1. Adding or subtracting capacitance from the system to move the parallel resonance frequency to one that is not harmful. 2. Adding tuned harmonic suppression reactors in series with the capacitor to prevent resonance. 3. Altering the size of the non-linear devices. Top of Page 4. Why tune to the 5th harmonic? The 5th harmonic is generally considered to be the most offending. It is important that the tuned frequency for the 5th harmonic be at least at the 4.2nd harmonic. Tuning slightly below the offending harmonic will accommodate for standard tolerances in the manufacturing process, but remove the largest offending portion of the 5th harmonic. Parallel resonance will occur around the 4th harmonic, at a much lower amplitude and in an area that does no harm to the capacitors or system. Many other systems are designed at the 3.78th harmonic to help extend the life of the capacitors. This tuning frequency does not remove the majority of the 5th, 7th, etc. harmonic from the system. Top of Page 5. How do I fulfill IEEE 519? We plan to sell several low voltage 6-pulses drives in Columbia, SA.  These drives are coming from New Berlin, WI.  They are looking for a passive filter supplier to include in the drives to mitigate the harmonic level and to fulfill IEEE 519.  What does this require? A. For IEEE-519 there are five different harmonic current distortion limits depending on the transformer size and impedance (determines available short circuit current) and the individual load ratings.  For several VFDs (at one location) it then becomes a system solution whereby you might combine AC line reactors along with filters to achieve compliance at the lowest cost.  It would be helpful to know the model of drive. Top of Page

### MYRON ZUCKER INC. products are designed to:

• Improve power factor
• Eliminate utility penalties or surcharges
• Increase available distribution capacity
• Mitigate harmonic distortion
• Protect sensitive equipment
• Decrease downtime
• Reduce line losses and associated cost
• Comply with industry standards

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