Power Quality Analysis Identifies Uneven Phase Loading at an Institutional Facility

Major Findings

1. Uneven Phase Loading Was Identified

The phase currents were approximately 143 A, 84 A and 121 A. The substantial difference between the highest- and lowest-loaded phases indicated that the connected loads were not evenly distributed across the three phases.

The average current unbalance was approximately 13.5%, with recorded values varying from around 12% to 18% during the assessment.

Continued operation with uneven phase loading can contribute to:

• Increased current in certain phases
• Additional heating of conductors and connections
• Reduced operating efficiency
• Greater stress on electrical equipment
• Increased neutral current
• Reduced utilization of available electrical capacity

2. Significant Neutral Current Required Attention

A neutral current of approximately 58 A was recorded during the measurement period.

Neutral current can be influenced by unevenly distributed single-phase loads, harmonic-producing equipment and other load characteristics. The recorded value indicated a need to inspect the neutral circuit and determine the contributing loads.

Recommended checks included:

• Condition and capacity of the neutral conductor
• Tightness of neutral terminations
• Signs of overheating or insulation deterioration
• Distribution of single-phase loads
• Contribution from non-linear electronic loads

The recorded neutral current does not by itself confirm a defect. However, it provides a clear reason for further inspection and corrective evaluation.

3. Harmonic Levels Were Within the Assessment Criteria

The Total Demand Distortion was measured at 6.86%, which remained within the reference limit applied during the assessment.

Voltage harmonic distortion was also within the applicable assessment criteria during the measurement period. Therefore, harmonic distortion was not identified as the primary concern under the recorded load condition.

Since harmonic levels can vary as equipment switches on and off, longer-duration monitoring may be considered where plant loading changes significantly during different shifts or operating cycles.

4. Voltage Conditions Remained Stable

The phase voltages remained between approximately 223 V and 226 V, while voltage unbalance was recorded at 0.62%.

These results indicated that the incoming voltage was comparatively stable and balanced during the assessment.

The study therefore showed an important distinction: the supply voltage was balanced, but the connected load currents were unevenly distributed.

5. Power Factor Was Acceptable

The average power factor was recorded at 0.93 during the measurement period.

This was considered acceptable for the assessed operating condition. However, power factor should continue to be monitored because it can change with variations in equipment loading, motor operation and capacitor-bank performance.

Recommendations

Based on the assessment findings, the following actions were recommended:

• Review the distribution of connected loads across all three phases.
• Transfer suitable single-phase loads from the heavily loaded phase to the lightly loaded phase.
• Inspect the neutral conductor for signs of overheating, damage or inadequate capacity.
• Check and tighten neutral and phase terminations.
• Conduct thermographic inspection of the main incomer, neutral conductor and major distribution connections.
• Identify equipment contributing significantly to neutral current.
• Verify phase loading after completing load redistribution.
• Repeat the power quality measurement after corrective action.
• Consider longer-duration monitoring where loading varies across shifts or operating cycles.

Any load redistribution should be planned and implemented by qualified electrical personnel after reviewing the complete electrical distribution arrangement.

Value Delivered

The power quality analysis helped the facility distinguish between satisfactory operating conditions and areas requiring corrective attention.

The assessment confirmed that:

• Incoming phase voltages were comparatively stable.
• Voltage unbalance remained low.
• Harmonic levels were within the applied assessment criteria.
• The average power factor was acceptable.
• Phase currents were unevenly distributed.
• Neutral current required further inspection and evaluation.

This provided the facility with:

• A measured power quality baseline
• Clear evidence of phase-load imbalance
• Identification of neutral-current concerns
• Prioritized corrective recommendations
• Direction for follow-up inspection and measurement
• Better information for preventive maintenance planning

Conclusion

The assessment demonstrated that acceptable voltage and harmonic conditions do not necessarily mean that the entire electrical system is operating optimally.

Although the incoming voltage remained balanced and harmonic distortion was within the assessment criteria, the phase-current variation revealed uneven load distribution. The recorded neutral current further highlighted the need to inspect the neutral circuit and connected single-phase loads.

Correcting the load distribution and repeating the measurements can help the facility verify improvement and reduce unnecessary electrical stress.

Need a Power Quality Assessment?

Uneven phase loading, neutral-current problems, harmonic distortion and voltage disturbances may remain unnoticed until they contribute to overheating, nuisance tripping or equipment failure.

Three Phase Techno Solutions provides power quality audits, harmonic analysis and electrical-system assessments for industrial, commercial and institutional facilities.

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