How can you troubleshoot power system harmonics with filters?

1 Measuring harmonics

The first step to troubleshoot harmonics is to measure them using a power quality analyzer or a harmonic analyzer. These devices can capture and display the voltage and current waveforms, the total harmonic distortion (THD), and the individual harmonic components of each phase. You can use these measurements to identify the sources and levels of harmonics in your system, and compare them with the standards and limits set by IEEE 519 or other relevant codes.

3 Filtering harmonics

The final step is to filter the harmonics using passive or active filters. Passive filters are combinations of capacitors, inductors, and resistors that create a low impedance path for certain harmonic frequencies, and divert them from the system. Active filters are electronic devices that inject a compensating current that cancels out the harmonic current from the load. You can use filters to reduce the THD, improve the power factor, protect the equipment, and comply with the standards. You can choose the type, size, location, and configuration of the filters based on your system characteristics, harmonic levels, and objectives.

4 Selecting filters

To select the best filter for your system, you need to consider several factors, such as the filter performance, cost, maintenance, and compatibility. You can use criteria, such as the filter rating, the harmonic attenuation, the power factor correction, the efficiency, the installation space, and the control system, to compare different filter options. You can also use software tools, such as Harmonic Advisor, to design and optimize your filter solution.

5 Installing filters

To install the filters, you need to follow the manufacturer's instructions and the best practices for safety and quality. You need to ensure that the filters are properly connected, grounded, and protected. You also need to verify that the filters are compatible with your system voltage, frequency, and configuration. You need to avoid creating parallel resonance or overcompensation with the filters, which can worsen the harmonic problems. You can use test equipment, such as a power quality analyzer or a harmonic analyzer, to check the filter performance and the system parameters after installation.

6 Maintaining filters

To maintain the filters, you need to monitor, inspect, and service them regularly. You need to check the filter status, the harmonic levels, the power factor, and the system performance using the filter indicators, the software tools, or the test equipment. You need to identify and correct any faults, such as filter failures, component degradation, or system changes, that can affect the filter operation and efficiency. You also need to follow the manufacturer's recommendations and the industry standards for filter maintenance and replacement.

7 Here’s what else to consider

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