Power Quality Logger for Long Term Energy Audits

The Need for Continuous Logging

Spot measurements miss the events that matter most: a 200 ms voltage sag at 03:14, a harmonic spike during weekly furnace cycles, a flicker incident triggered by an arc welder upstream. A continuous power quality logger captures these events 24/7 for periods of one to four weeks, providing the evidence needed to justify upgrades or settle utility disputes.

Required Capabilities

• Three-phase voltage and current with neutral and ground channels.
• 10/12 cycle aggregation per IEC 61000-4-30 Class A.
• Harmonics up to 50th order with interharmonics.
• Voltage sag/swell/interruption capture with 1 ms resolution.
• Flicker measurement (Pst, Plt) per EN 50160.
• Internal storage of at least 32 GB and battery backup.

Audit Workflow

Define the audit objectives - billing accuracy, equipment troubleshooting, or compliance verification. Install the logger at the point of common coupling for at least one full operating cycle (often 7 to 14 days). After retrieval, generate the EN 50160 conformance report and a parallel harmonic trend report.

Common Findings

• Persistent over-voltage on weekends when load drops.
• 5th and 7th harmonic distortion above 8% from VFD-driven motors.
• Recurring 100 ms sags during transformer tap-changer operations.
• Power factor below 0.85 triggering utility surcharges.

EK / ETCR Recommendation

Choose an IEC 61000-4-30 Class A logger with PDF report generation, browser-based remote configuration, and at least 4 GB recording capacity for routine industrial audits.