Electrical harmonics measurement services

1. What are harmonics?

Harmonic components affect power quality and warrant investigation when distortion exceeds the applicable limits. Their frequencies are integer multiples of the fundamental frequency; for example, 250 Hz is the fifth harmonic in a 50 Hz system.

Harmonic currents can increase losses and heating and can affect equipment performance. Their impact depends on the harmonic spectrum, loading and the electrical system.

2. Effects of harmonics

Harmonics may cause cables to overheat and insulation to deteriorate. Motors may overheat, generate noise or experience torque pulsations, mechanical resonance and vibration. Capacitors may overheat and suffer dielectric damage. Lighting or displays may flicker, protection may trip unexpectedly, computers and networks may malfunction, and measurements may be affected.

3. How are harmonics generated?

Nonlinear loads draw nonsinusoidal current, introducing harmonics into the distribution system. Examples include power-electronic motor starters and drives, computers and other electronic equipment, electronic lighting and welding power supplies.

4. Harmonic mitigation

• Use suitably designed harmonic filters.
• Review load arrangement and equipment selection to reduce harmonic injection into the supply.

5. ITVC measurement services

ITVC Global provides harmonic measurement and analysis for factory electrical systems.

1. Conduct a preliminary review of the electrical system.
2. Prepare the measurement plan, personnel and equipment.
3. Measure harmonics at the facility.
4. Collect and process the data.
5. Prepare the report.

Example measurement results

Measurement parameters and scope

• Continuously record current, voltage, power and power factor over an agreed period, store the data and analyse the results. The source describes logging at 1-second intervals for shorter studies or 15-second intervals for longer studies, depending on instrument configuration.
• Measure harmonics on individual branches and across the factory network, identify contributing equipment and recommend mitigation measures.

Personnel and equipment

• Personnel: energy auditors and engineers specialising in industrial electrical systems.
• Equipment: multifunction electrical power and energy analysers.