Power Quality Issues ? Case Studies with Root Cause Analysis & Solutions by SEA Energy

Power quality audits, regardless of process or equipments generally follow a similar methodology and uncover similar issues across different sectors.

• Audit Methodology:

  
  

  1. Baseline Data Collection: Collecting energy bills, electrical drawings (SLDs), and equipment lists.

  2. Power Quality Measurement: Deploying advanced Power Quality Analyzers (PQA) at strategic points (e.g., Main Distribution Panel, sensitive loads) to log parameters over a period (days/weeks).¹

     
     

  3. Root Cause Analysis (RCA): Analyzing logged data (harmonics, sags, swells, transients, unbalance, PF) to match disturbances with operational events (e.g., a sag correlating with a motor start).

  4. Recommendations & Outcome: Proposing solutions (e.g., filters, UPS, surge protection, grounding fixes) with a cost-benefit analysis.

Power Quality Issue	Typical Cause	Typical Solution
Harmonic Distortion	Non-linear loads (VFDs, LED lighting, computers, UPS)	Active or Passive Harmonic Filters
Voltage Sags/Dips	Utility faults, motor starting, large load switching	UPS, DVR (Dynamic Voltage Restorer), Sag Corrector
Voltage Unbalance	Uneven distribution of single-phase loads across the three phases	Load redistribution, Voltage Regulators

Here is the few case studies from different industrial sector related power quality issues, its impact along with SEA Energy recommended solution based on Power Quality study and Root cause analysis.

Sector	Issue Before Audit	Root Cause Analysis (Measurement & Findings)	Outcome & Solution
Industrial (Steel Plant)	Frequent tripping of variable speed drives (VSDs) on the rolling mill; motor overheating.	Measurements: High current harmonic distortion (THDi), exceeding IEEE 519 limits, caused by the large, unfiltered VSDs.	Outcome: Stable VSD operation, reduced motor temperature. Solution: Installation of Active Harmonic Filters (AHF) to inject compensating current and suppress harmonics.
Commercial (Shopping Mall)	Intermittent failure of electronic point-of-sale (POS) systems; flickering LED lights during peak hours.	Measurements: Severe voltage sags (dips) during simultaneous start-up of large HVAC units and escalators. The supply also had minor voltage unbalance.	Outcome: Reliable POS operations and stable lighting. Solution: Installation of a Dynamic Voltage Restorer (DVR) or voltage stabilizers at critical feeder points, and load redistribution for unbalance.
Education (University Campus)	Overheating of main distribution transformers; nuisance tripping of feeder breakers.	Measurements: High neutral current and elevated Voltage Total Harmonic Distortion (VTHD). Root cause was large quantities of non-linear single-phase loads (PC labs, LED lighting, servers).	Outcome: Transformer temperature normalized, tripping eliminated. Solution: Installation of a de-rating factor on transformers (due to harmonics) and installation of a 3-phase 4-wire Active Harmonic Filter to mitigate both current and neutral harmonics.
Industrial (Textile Mill)	High electricity bills with significant power factor penalties.	Measurements: Low lagging power factor (0.75) due to many induction motors. PF correction capacitors were underperforming.	Outcome: Power factor improved to average 0.99, eliminating penalties and reducing energy losses. Solution: Replacement of old/failed capacitors and installation of a new, well-tuned Automatic Power Factor Correction (APFC) panel.
Commercial (Hotel)	Data corruption in the building management system (BMS) and frequent computer crashes in administration.	Measurements: High-frequency electrical noise (transients/notching) found on low-voltage lines, traced back to switching power supplies and poor grounding practices.	Outcome: Data integrity restored, no more computer crashes. Solution: Installation of Isolation Transformers for sensitive equipment and a complete review and correction of earthing and grounding system per code.

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