What is power quality monitoring?
Measuring and logging the quality of the supply, so a sag, distortion or drift is seen and recorded before it trips a regulator.
Power quality monitoring is the continuous measurement and logging of the quality of the electrical supply: voltage level, sags, swells and interruptions, harmonics, frequency, phase unbalance and power factor. A power quality analyser at the substation records each event with a timestamp, so the supply can be trended and a problem traced to its source.
It matters for airfield lighting because the constant-current regulators are non-linear loads that can distort the supply, and they can in turn be disturbed by a poor one. A generator has a higher source impedance than the utility, so it is more sensitive to distortion. A sag, an interruption or heavy distortion can trip a regulator or upset the control system, and without a record it is hard to tell a supply problem from an equipment fault.
- Choose the points. Usually the low-voltage main bus, and often the generator output as well.
- Fit the sensing. Current transformers, and voltage transformers or protected direct voltage connections within the analyser’s rating, give the analyser safe signals sized for the circuit. Never leave a live current transformer’s secondary open-circuit: it can develop a dangerous voltage.
- Set up the analyser. Set thresholds and logging intervals, and synchronise its clock with the rest of the system.
- Connect the alarms. Bring threshold events to the ALCMS or SCADA so they are seen when they happen.
- Review the trends. Look for slow changes such as growing distortion or a drifting voltage.
- Investigate events. Compare the event time with regulator alarms and the generator and changeover log, and record the finding.
Frequently Asked Questions
Q1What is power quality monitoring?
It is the continuous measurement and logging of the quality of the electrical supply, including voltage level, sags, swells and interruptions, harmonics, frequency, phase unbalance and power factor. An analyser records events with timestamps so problems can be seen, trended and traced.
Q2Why does power quality matter for airfield lighting?
The constant-current regulators are non-linear loads that can distort the supply, and they can also be disturbed by a poor supply. A sag, an interruption or heavy distortion can trip a regulator or upset the control system, and a generator, with a higher source impedance than the utility, is more sensitive to distortion.
Q3Where should the analyser be connected?
Usually at the low-voltage main bus, where the supply to all the airfield loads can be seen together, and often also at the generator output. The exact points depend on the design. Connect it through current transformers and voltage sensing (voltage transformers, or protected direct connections within the analyser’s rating) sized for the circuit, following the site's isolation and permit-to-work procedure. Never leave a live current transformer’s secondary open-circuit.
Q4How is power quality data used?
Alarms show when a threshold is crossed, trends show slow changes such as growing distortion or a drifting voltage, and event records help tell a supply problem from an equipment fault. Comparing the event time with regulator alarms and the generator and changeover log is a common fault-finding step.
Q5Which standards apply to power quality measurement?
IEC 61000-4-30 defines how power quality parameters are measured, EN 50160 describes the voltage characteristics of public supply, and IEEE 519 and IEEE 1159 cover harmonic limits and monitoring practice. The limits that apply on your site come from the utility agreement and the authority's requirement.
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