Power Quality Monitoring

Risks of Poor Power Quality

Power Quality Monitoring: Risks of Poor Power Quality

Power quality monitoring makes it visible why “invisible” power quality disturbances in buildings, industry, and private installations can lead to outages, follow-up costs, and quality issues. The article is aimed at operators of commercial buildings, industrial companies, electrical contractors, and grid operators who want to detect disturbances early and avoid damage. The technical focus is the systematic classification of typical power quality events such as harmonics, voltage dips, flicker, transients, and unbalance, combined with a practical measurement and evaluation workflow. The goal is to make risks and KPI impacts tangible so that concrete technical measures can be derived.

Key Takeaways

Unclean power quality often causes gradual damage: heat build-up, efficiency losses, and reduced equipment lifetime usually appear long before a major failure occurs.
Many disturbances remain undetected because they occur only sporadically or manifest as “unexplainable” malfunctions in IT systems, LED lighting, drives, and control equipment.
Typical consequences include malfunctions, production and quality losses, unexpected tripping of protective devices, and costly service interventions.
A structured power quality monitoring approach combines suitable measurement points such as sockets, feeders, and transformers with standards-based evaluation according to EN 50160 or IEC 61000.
Mobile analyzers are ideal for fast root-cause checks, while permanently installed systems enable continuous monitoring and reliable KPI evidence over weeks or months.
Centralized evaluation of measurement data simplifies prioritization, reporting, and the sustainable reduction of disturbance-related costs, especially in complex systems and multi-site environments.

Introduction

Unclean power quality is rarely “just slightly bad electricity”; it represents a real operational and economic risk. Modern loads such as LED drivers, variable speed drives, UPS systems, server power supplies, charging infrastructure, and automation equipment are highly sensitive to voltage deviations and waveform distortion. The result can be heat generation, sporadic malfunctions, flicker, communication problems, or unexplained resets.

This is exactly where power quality monitoring comes into play. It translates electrical anomalies into understandable causes, affected assets, and quantifiable follow-up costs. Instead of fighting symptoms by replacing components or restarting systems, the actual source of disturbance is identified based on measurement data.

Organizations that systematically measure and evaluate power quality can reduce unplanned downtime, avoid service calls, and extend the service life of their assets. This is particularly relevant in commercial buildings and industrial environments where availability and efficiency are critical.

technician performing power quality monitoring at a switchgear cabinet using a PQ-Box 300 — Figure 1: Power quality disturbances often remain invisible until measurement clearly identifies the root cause

What Does “Unclean Power” Mean in Practice?

Unclean power quality refers to deviations from the ideal sinusoidal supply voltage and frequency, as well as disturbances that appear either as short-term events or as permanent characteristics. Typical categories include:

Voltage deviations and slow fluctuations above or below nominal values
Short-term events such as voltage dips, swells, interruptions, and transients
Distortions such as harmonics, interharmonics, and high-frequency interference
Flicker that leads to visible light fluctuations
Voltage unbalance in three-phase systems

An important aspect is that many of these effects are not immediately dramatic. Gradual impacts such as additional heating, reduced efficiency, and accelerated aging of capacitors and power supplies are often the main cost drivers over time.

Applications and Use Cases

PQ-Box ONE power quality analyzer connected to a socket for power quality monitoring — Figure 2: PQ-Box ONE - power quality analyzer designed for socket-based measurements

Commercial Buildings: Building Services, LED Lighting, Elevators, IT-Rooms

Problem: In office and commercial buildings, LED lighting, elevator drives, HVAC systems, switch-mode power supplies, and often PV or storage systems operate in parallel. This combination leads to distortion and events that manifest as flicker, humming noises, communication issues in building management systems, or sporadic failures of power supplies.

Approach: Measurements are performed at sockets close to critical loads such as IT racks or LED clusters, and additionally at distribution boards to limit the propagation of disturbances. Short-term events like dips during motor starts are captured via event recording, while long-term indicators are evaluated over days or weeks.

Benefit: Faster root-cause analysis, fewer trial-and-error service visits, and better coordination between electrical contractors, lighting specialists, and building services teams. For quick socket-based measurements, compact analyzers such as the PQ-Box ONE can be used directly at the point of use and support standards-oriented evaluation.

Industry: Automation, Sensors, Drives, Process Quality

Problem: Production lines do not tolerate sporadic control errors. Voltage unbalance, dips, or high distortion can cause false triggering, sensor resets, fieldbus disturbances, or quality losses without any obvious component failure.

Approach: Measurements are carried out at the point of common coupling and at selected feeders supplying major loads such as large drives, welding equipment, or compressors. Event timestamps are correlated with process data to identify when scrap occurred, when a line stopped, and which protective devices tripped.

Benefit: Measurable reduction in downtime, less scrap, and lower pressure on spare parts and service teams. For continuous low-voltage monitoring, permanently installed Class A analyzers such as PQI-LV are suitable to provide long-term transparency.

PQI-LV device for continuous power quality monitoring in low-voltage networks — Figure 3: PQI-LV - transparency deep inside low-voltage power distribution

Private Households: High Electronics Density, PV, EV Chargers, Unexplained Failures

Problem: Modern households increasingly use switch-mode power supplies, PV inverters, heat pumps, and charging infrastructure. Typical symptoms include flickering LEDs, humming devices, router or repeater failures, and recurring RCD or circuit breaker trips.

Approach: Measurements at typical problem sockets and, ideally, additional measurements at the distribution board to distinguish between external grid events and internal sources such as defective appliances or inverters.

Benefit: Clear differentiation between issues originating within the customer installation and those coming from the supply network, enabling faster and more targeted corrective actions.

IT and Communication Systems: Availability Instead of Troubleshooting

Problem: Sensitive IT and communication systems react strongly to short voltage dips, transients, and interference. The consequences are reboots, data errors, switch outages, UPS alarms, or intermittent communication failures.

Approach: Event recording with sufficient time resolution, long-term evaluation of voltage quality, and targeted measurements at the most sensitive points such as PDU supplies or UPS inputs and outputs.

Benefit: Improved system availability and a solid technical basis for protection concepts such as UPS parameterization, filtering, and supply design.

Typical Problems and Consequences: From Heat to Downtime

In practice, the following effects are particularly common when power quality disturbances are not detected and mitigated:

Increased heat generation and reduced service life: Harmonic distortion and voltage unbalance increase losses in cables, transformers, motors, and power supplies.
Malfunctions and sporadic resets: Short-duration events or interference voltages appear as “random faults” in control systems and IT infrastructure.
Shortened lifetime of electronic equipment: Capacitors, driver stages, and power supplies age faster under additional thermal and electrical stress.
Unexpected tripping of protection and safety devices: Protective equipment reacts to current peaks, leakage or residual currents, and distorted waveforms.
Disturbances in control systems, sensors, and automation: Communication issues and reference problems lead to incorrect measurements or process interruptions.
Higher energy losses and reduced efficiency: Increased reactive power, higher currents, and additional heating result in sustained energy losses.
Impairment of sensitive IT and communication systems: Interruptions, packet loss, fault states, and system outages occur.
Quality issues in production processes: Scrap, rework, and losses in overall equipment effectiveness (OEE).
Acoustic noise, humming, or LED flicker: Typical “symptoms” that often indicate flicker or waveform distortion.
Risk of unplanned downtime and costly service interventions: The most expensive scenario combines unplanned outages with a cascade of follow-up costs.

Figure 4: Power quality monitoring in practice: analyzer records voltage quality and events, evaluation is performed on a laptop

Functions and Benefits

What Effective Power Quality Monitoring Must Deliver

A robust power quality monitoring solution provides three things at the same time:

Standards-compliant indicators that are comparable and suitable for documentation
Event correlation that shows exactly what happened and when
Localization to identify where the disturbance actually originates

This typically includes voltage quality according to relevant standards, recording of dips, interruptions, and transients, analysis of harmonics and interharmonics, flicker, unbalance, power and energy parameters, and clear reporting of limits and violations.

Device Concepts: Mobile Checks, Permanent Monitoring, Centralized Evaluation

Mobile measurements are ideal when a problem is new, needs to be localized quickly, or measurement points change frequently. A socket-based measurement can already indicate whether a local issue exists. The PQ-Box ONE is designed for such fast analyses at the socket and supports evaluation according to applicable standards, with data analyzed via mobile software or app-based tools.

Permanent monitoring is recommended when disturbances occur rarely, availability is critical, or evidence is required for third parties such as utilities, service providers, or internal compliance. In these cases, permanently installed analyzers such as PQI-LV for low-voltage networks or more advanced systems for broader applications are used.

For complex grids and expert applications, devices such as PQI-DE can be applied as combined power quality analyzers and disturbance recorders, serving as central components for grid-related measurement tasks and interfaces to control systems.

Centralized Analysis and Reporting

As soon as multiple measurement points or sites are involved, evaluation becomes decisive. Centralized analysis software supports comparison of measurement points, standardized reporting, and repeatable KPI evaluations. WebPQ® is described by A. Eberle as a central analysis platform for permanently installed power quality devices, enabling structured evaluation of events and standards compliance.

Optional: Monitoring Feeders Instead of Only the Transformer

If the question is not only whether a problem exists but in which feeder it originates, additional transparency is required. With iSense technology, current measurements for multiple feeders can be combined with permanently installed analyzers, enabling more precise localization in substations and distribution systems.

Symptoms, Causes, Impacts: Practical Overview

Symptom in operation	Typical power quality cause	Common impacts and costs
LED flicker or humming	Flicker, harmonics, interharmonics	Complaints, replacements, comfort and quality loss
Unexplained resets of control systems or IT	Voltage dips, transients	Downtime, data loss, service interventions
Unexpected tripping of protective devices	Current peaks, leakage currents, distortion	Production interruptions, troubleshooting effort
Heating of cables, transformers, motors	Harmonics, unbalance, increased currents	Efficiency losses, aging, safety risks
Process quality issues	Events affecting sensors and drives	Scrap, rework, OEE losses
Communication disturbances	Interference, transients, grounding issues	Network outages, false alarms

Practical Workflow: Measurement → Evaluation → Result

1) Define a Measurement Strategy Without Over-measuring

Start with a clear hypothesis: which loads are affected, when does the problem occur, and which events are plausible? Based on this, select measurement points close to the symptom and suitable reference points such as distribution boards or the grid connection. Mobile measurements are sufficient for fast checks, while rare events require measurement periods of several days or weeks.

2) Standards-based Evaluation and Event Correlation

Evaluation combines statistical indicators and limit values with detailed event analysis. Suitable software links events and standards-based parameters in reports. For mobile measurements, WinPQ mobil supports the preparation and visualization of data according to relevant standards.

3) Translate Results Into Measures

Effective power quality monitoring does not stop at detection. It leads to concrete actions such as identifying the disturbance source, selecting technical measures like filtering or parameter adjustments, and verifying success through before-and-after measurements and KPI reports.

Results and KPI Effects: Measurable Improvements

KPIs depend on the application and initial situation, but typical effects after systematic power quality monitoring include fewer unplanned downtimes, reduced service and troubleshooting costs, longer asset lifetimes, more stable processes with less scrap, and improved energy efficiency. Often, the first major benefit is transparency itself, as clear evidence of when and where disturbances occur accelerates decision-making.

FAQ - Frequently Asked Questions

What is power quality monitoring in one sentence?

Power quality monitoring is the continuous or event-driven measurement and evaluation of voltage and supply quality to detect, assess, and eliminate disturbances.

Why do malfunctions often occur only sporadically?

Many power quality events are very short or occur only under specific operating conditions. Without event recording, they appear as random errors even though they are electrically measurable.

Which symptoms most strongly indicate power quality disturbances?

Typical indicators include LED flicker or humming, unexplained resets, communication dropouts, recurring protection trips, increased heating, and process quality issues without mechanical faults.

Is a socket measurement sufficient?

For an initial assessment, often yes, especially if the symptom is local. For rare events or long-term evidence, extended measurements at multiple points are recommended.

Which A. Eberle products are suitable for quick checks and permanent monitoring?

The PQ-Box ONE is suitable for fast analyses at the point of use. For continuous low-voltage monitoring, PQI-LV can be applied, while PQI-DE or PQI-DA smart are used for more complex measurement tasks depending on network level and requirements.

How can measurement data be translated into management-ready results?

By using standardized reports, a clear before-and-after logic, and KPIs such as downtime, service effort, scrap rates, and energy indicators. Central evaluation solutions like WebPQ® support structured reporting and interpretation.

Conclusion: → Reducing Risk Starts With Transparency

Unclean power quality is one of the most common causes of gradual aging, inefficient operation, and difficult-to-explain disturbances. Organizations that want to reduce risk, downtime, and costs need power quality monitoring that reliably captures both standards-based indicators and events. In practice, a structured approach pays off: measure correctly, evaluate clearly, derive measures, and verify success. This turns mysterious faults into a manageable and economically optimized operation.

Our Special Application Series (Videos in German only):

Current issues about Power Quality

Changes in Energy Technology - Part 1

In this article, which we created together with the web portal Schutztechnik.com, we discuss the current changes in the energy technology. In addition, we will look on the effects of grid disturbances and what influence they have on measuring devices with which we detect faults in the grid.

Changes in Energy Technology - Part 2

Standards play a major role for power quality measurements. Accordingly, it is essential that these standards are also adapted to the new conditions in the course of the change in energy technology. In the second article of our series, we look at the current standards and how they should be interpreted with regard to high switching frequencies.

Power Quality Measurements:
The N-Conductor & Harmonics

In power quality measurements, odd harmonics such as the 15^th, 21^st & 27^th are often violated. What are harmonics anyway, how does this circumstance occur and what influence does this have on the neutral conductor. This article deals with these questions and sheds light on this matter.

Power Quality Measurements:
The 3rd Harmonic

The report "The N conductor & Harmonics" already explained the special features of the The report "The N conductor & Harmonics" already explained the special features of the harmonics divisible by 3 and why they add up on the neutral conductor. This special publication intends to illustrate a typical power quality measurement and the aspects, which should be taken into consideration conducting the measurements. The measurements displayed in this report took place in an office building where increasing problems with the power quality were detected.