Power quality guide
Power quality monitoring: what each reading points to.
Poor power quality rarely shows up as a line on the bill. It shows up as motors running hot, capacitors failing, drives tripping and breakers going for no clear reason. Monitoring the supply on each panel turns those mysteries into readings you can act on.
What to monitor, and what it tells you
| Reading | Watch for | Usually points to |
|---|---|---|
| Voltage | Too low or too high, or swinging with load | Supply problems, overloaded transformer, long or undersized cables |
| Voltage unbalance | Phases drifting apart | Supply-side unbalance or a failing component. See phase imbalance |
| Frequency | Away from 50 Hz | Usually DG running, or a DG governor problem |
| Power factor | Low lagging, or leading | Capacitor bank problems. See improve power factor |
| Current and neutral current | One phase high, neutral high | Single-phase loads on one phase, or harmonics |
| Harmonics (THD) | Rising voltage or current distortion | VFDs, UPS, rectifiers and LED drivers |
Low voltage
Your state’s Supply Code sets the voltage band the DISCOM must hold at your connection. When voltage sits low, motors draw more current for the same work, run hotter and trip more often. Check the incomer first: if voltage is low there, record it over days and raise it with the DISCOM. If the incomer is fine and one panel is low, look at that feeder’s cable and joints.
Harmonics
Variable frequency drives, UPS systems, rectifiers and LED drivers draw current in pulses, not a smooth wave. That distortion, measured as total harmonic distortion (THD), heats transformers and neutral conductors and is a common reason capacitor banks fail early.
| Bus voltage | Voltage THD limit (IEEE 519-2014) |
|---|---|
| Up to 1 kV | 8% |
| Above 1 kV up to 69 kV | 5% |
Many multifunction meters report THD per phase. A plant adding drives to a capacitor-corrected bus should watch it before and after, and use detuned capacitor banks where THD is high.
Supply interruptions
Short outages and dips restart machines, scrap batches and start everything up at once, which can set Maximum Demand. A record of every interruption, with its duration, is the evidence a DISCOM complaint needs.
Power quality in KONDUKTOR® EMS
- Voltage, frequency, power factor and per-phase current on every meter, live and in history.
- Voltage and current unbalance on three-phase meters.
- THD and neutral current where your meter reports them.
- Supply interruptions recorded with duration, and an alert on any reading crossing a limit you set.
- Power factor shown as lagging or leading, so a bank over-correcting at night is visible.
Common questions
What does a power quality monitor measure?+
Voltage, frequency, voltage and current unbalance, power factor, current per phase and neutral, and harmonic distortion (THD). Together they show whether the supply and the plant’s own loads are stressing motors, capacitors and cables.
Can low voltage increase the electricity bill?+
Indirectly. Motors draw more current at low voltage for the same work, so losses rise and motors run hotter and fail sooner. The bigger cost is usually breakdowns and trips, not the units.
Why do capacitors fail in plants with VFDs?+
Drives create harmonic currents, and a capacitor bank can resonate with the supply at one of those frequencies. Current through the capacitors rises and they overheat. Detuned banks, with series reactors, avoid the resonance.
See your supply’s quality on every panel.
Book a live demo and see voltage, unbalance, power factor and harmonics on meters like yours.