As Seen in PQ NewsBeat: What Electrical Contractors Need to Know About Harmonics

In his latest EC&M PQ NewsBeat article, Ross Ignall explains how harmonics can contribute to overheating, nuisance tripping, equipment faults, and other electrical problems. 

Harmonics are distortions in electrical waveforms caused by nonlinear loads like VFDs, LED lighting, and UPS systems, which pollute the power supply and can lead to equipment issues.

Triplen harmonics (multiples of three) can cause neutral conductor overheating and pose risks of insulation failure and equipment damage due to their in-phase behavior in three-phase systems.

Effective harmonic mitigation involves measurement, analysis, and implementing solutions like filters and proper system design to prevent costly downtime and extend equipment life.

Read “Harmonics: What Electrical Contractors Need to Know, Part 1” in EC&M’s PQ NewsBeat.

Frequently Asked Questions

What causes harmonics in an electrical system?

Harmonics are often caused by nonlinear loads that draw current in pulses. Common sources include variable-frequency drives, LED lighting, uninterruptible power supplies, computers, battery chargers, inverters, and other electronic equipment.

Why can harmonics overheat a neutral conductor?

Triplen harmonics, including the 3rd, 9th, and 15th harmonics, do not cancel in the neutral conductor of a three-phase system. Instead, they add together. This can produce higher neutral current and lead to overheating.

How can electrical contractors identify harmonic problems?

Contractors can use a power quality instrument to record waveforms, harmonic levels, total harmonic distortion, RMS values, and related electrical events. These measurements help locate the source and guide the next step.