What it is and when you need it
A power quality analysis looks at several days of measurements to see what voltage and current really look like in your installation: waveform, magnitude, phase balance and disturbances. From those measurements we assess whether the installation meets the applicable limits and find the cause of failures with no obvious explanation.
We do it for industrial plants and for medium, high and extra-high voltage (EHV) substations. It is usually requested when:
- Variable frequency drives, UPS units or electronic equipment trip for no apparent reason.
- Transformers, cables or neutrals run hot, or capacitors fail.
- A reactive power penalty arrives, or the utility asks you to demonstrate compliance.
- You are about to install a capacitor bank, a filter, solar generation or large non-linear loads.
- Lighting flicker is visible.
It is part of our engineering design and studies service.
What is included
- Harmonics: voltage total harmonic distortion (THD), current total demand distortion (TDD) and individual harmonics, with their trends over time.
- Voltage variations: sags (dips), swells, interruptions and long-duration variations, with magnitude, duration and time stamp.
- Voltage unbalance, as the ratio of negative-sequence to positive-sequence voltage.
- Flicker: short-term (Pst) and long-term (Plt) severity indices.
- Power factor, active, reactive and apparent power, and load profile.
- Frequency and any transients the recorder was able to capture.
- Diagnosis and recommendations, with concrete solutions and their priority.
How we work
The analysis is remote; the measurement campaign is field work. In Colombia our team can run it. Elsewhere, your local team or contractor performs it following our measurement plan, or we travel on request.
- Planning. We define the goal: compliance at the PCC, finding a root cause or sizing compensation. From that we set the measurement points, the duration and the event trigger thresholds, and write a measurement plan.
- Recorder installation. The campaign uses IEC 61000-4-30 Class A power quality recorders, connected to the CTs and VTs or directly at low voltage, with the clock synchronized.
- Measurement. Usually one continuous week or more. When you can share data during the campaign, we check it early to catch any connection problem in time.
- Analysis. We process the recordings, apply the statistical assessment of each standard and correlate events with plant operation: motor starts, capacitor switching or utility switching operations.
- Report and recommendations. We deliver the results, the comparison against limits and the proposed actions, explained in a video call with your team. Our team works from Bogotá (UTC−5).
Standards and criteria
Measurements must come from IEC 61000-4-30 Class A instruments. That standard sets the measurement methods, aggregation intervals (for example 10 minutes and 2 hours) and uncertainty. With it, two Class A recorders give the same result on the same signal, which matters if the study is discussed with the utility. Harmonics are measured per IEC 61000-4-7 and flicker per IEC 61000-4-15 (adopted in North America as IEEE 1453).
Harmonics are assessed with IEEE 519 at the point of common coupling. Voltage distortion limits depend on the voltage level. Current limits depend on the ratio between the short-circuit current at that point and the customer’s load current, so the study needs the short-circuit level at the point of interconnection. The assessment is statistical: weekly percentiles of the measured values are compared with the limits, not an isolated instantaneous reading. Where the utility uses IEC criteria, we also refer to IEC TR 61000-3-6 for emission limits and EN 50160 for supply voltage characteristics.
To classify sags, swells and interruptions we use the IEEE 1159 categories. For power factor and reactive energy we apply the local regulation and the terms of your contract with the utility, as you provide them.
Typical recommendations
The report does not stop at the measurements. It proposes solutions based on what we find, for example:
- Capacitor banks with detuning reactors or passive tuned filters, when reactive compensation is needed in the presence of harmonics. We check resonance risk first.
- Active filters when the harmonic spectrum varies a lot with load.
- Redistribution of single-phase loads to reduce unbalance.
- Sag ride-through: drive settings, UPS backup for control circuits or changes to the motor starting sequence.
- Review of neutrals and transformers serving non-linear loads.
What you receive
- Technical report with measurement points, recorder connection and campaign duration.
- Trend charts and compliance tables against IEEE 519 and the other agreed criteria.
- Voltage event log with its analysis.
- Root-cause diagnosis and prioritized recommendations.
- The processed data, so you can compare future campaigns.
Why Tiza Group
- One team from start to finish: the people who plan the measurement are the same who analyze it and explain the results to you.
- Field-proven criteria: our team knows the equipment that creates and suffers disturbances, from design to commissioning, in medium, high and extra-high voltage.
- Solutions you can execute: if the recommendation involves protection settings, we can follow through with a protection coordination study and remote relay configuration. Contact us to plan your analysis.