The issue of Power Quality (PQ) is more important than ever due to the increasing dependence on electrical supply. Even the smallest power outage has a negative economic impact on industrial and commercial consumers.
Unplanned plant shutdowns arise from:
- Circuit breaker trips
- Equipment failures
- Malfunction of equipment
- Poor power quality (on the electrical distribution networks feeding the plant equipment).
The automotive industry is at risk for PQ related issues. NEXTEC has been conducting PQ audits at several automotive manufacturing customers since 2015.
The PQ Audits revealed that non-linear loads cause distortion on the output of the transformers. These loads include:
- Robot controllers
- Spot welders
- Variable speed drives on motors (pumps, compressors)
- Fluorescent lights.
Distortions have an adverse impact on equipment performance and reliability. One option was to reduce voltage distortion through adjusting the transformer’s impedance. But this is neither practical nor economical. Instead, NEXTEC implemented an Active Harmonic Filter (AHF) solution on the transformer outputs.
The objective was to reduce the current and voltage harmonic levels. We proposed Schneider-Electric’s Accusine PCS+ AHF. It employs current transformers to measure the source current to determine the content of harmonic current present.
This approach reduces the harmful effects of harmonic current and voltage distortion. Injecting the synthesised current mitigates the harmonic currents through the transformers.
The reduced distortions permit other equipment to operate properly and enjoy a longer life span. We implemented and commissioned a total of 38 AHF units in automotive plants in the Pretoria area. The project was highly successful. The outcome was a reduction of Total Harmonic Distortion levels to within compatibility limits. The client gained improved current and less heat loss through the transformers.