Case Study 1: Modderbee, Ekurhuleni

In August 2023, during installation of a Power Quality Monitor at Modderbee substation, we detected a phase-to-neutral voltage discrepancy—below 2 volts instead of the expected 6.6kV. Phase-to-phase voltages appeared normal, but the imbalance suggested a blown fuse on the VT secondary side.

Using Symmetrical Component Analysis and current measurements, we diagnosed the issue and alerted authorities at the City of Ekurhuleni and Eskom for further action.

Case Study 2: Linden, Johannesburg

In April 2024, suspecting network imbalance in Linden, I installed a Power Quality Monitor at a residential site. Two phases showed significant voltage drops while the third remained stable. A near-zero phase-to-phase voltage between phases 2 & 3 confirmed the imbalance.

Findings were shared with City Power to prompt further investigation, though formal assessment is still pending.

The Global Perspective

Unbalanced networks are a global issue. From South Africa to beyond, many consumers remain unaware of the imbalances affecting their power supply. These conditions can lead to:

• Production losses due to Negative Phase Sequencing
• Reduced power factor in distributed generation
• Operational inefficiencies and financial losses

Raising Awareness

Since September 2023, I’ve shared findings via newsletters and platforms like LinkedIn, Facebook, and the Agulhas Utilities Corporation website. The goal: to prompt Eskom, City Power, and others to investigate power quality issues more seriously.

Despite these efforts, utility response has been limited—highlighting the urgent need for action.

Consequences of Asymmetrical Networks

Voltage imbalances affect motors, generators, transformers, and cables. A 1% voltage imbalance can cause 6–10% phase current imbalance, leading to:

• Overheating and reduced efficiency
• Shortened equipment lifespan
• Distorted motor speed and torque

Financially, these inefficiencies inflate electricity bills—often unnoticed by consumers but profitable for producers.

Harmonics in Renewable Energy

Power electronics in renewables introduce harmonic distortions, causing overheating and inefficiencies. Solid-state power meters help monitor these effects, but their accuracy in non-sinusoidal environments must be scrutinized.

In my blog “Power Quality Affecting Client Billing,” I explore how unbalanced and distorted voltage affects billing—and propose balanced billing as a fair solution.