By leveraging time-series measurement data, technicians can benchmark power quality events against equipment failure occurrences, thereby narrowing down root causes and enabling early mitigation of electrical failures
What is Power Quality Analysis ?
Power quality reflects the stability of voltage, current, frequency, and other electrical characteristics during power supply to loads. Power quality directly impacts the performance and lifespan of equipment and systems.
Power Quality Analysis is the process of measuring, monitoring, collecting, and evaluating power supply parameters (such as voltage, frequency, and waveform) to determine whether they are stable and within acceptable limits.
When time-stamped measurement data is available, technicians can cross-reference power quality events with the exact times equipment faults occur. This allows them to isolate root causes rather than merely treating external symptoms.
Root Cause Investigation
Power quality analysis enables technicians to record voltage, current, and abnormal events over time, helping to establish the direct relationship between the power supply and equipment anomalies:
Equipment self-resetting
PLC / Robot stoppages
Contactor tripping
VFD / Inverter faults
Motor overheating
Capacitor bank or transformer abnormalities
Power Quality Phenomena in Electrical Systems
Voltage Dips, Swells, and Interruptions
A voltage dip (sag) is a brief reduction in voltage below normal operational levels. Causes may include grid faults, large load switching, motor starting, or sudden load variations.
In automated production lines, even a short voltage dip can cause PLCs, robots, industrial PCs, or controllers to reboot. If these events occur intermittently, routine voltage checks with standard multimeters at the time of inspection may fail to catch them.
Power quality analyzers record time-stamped events to determine the exact magnitude, duration, and timestamp of dips, swells, or interruptions. This data can then be correlated with the machine’s error logs.
Voltage Transients and Fast Fluctuations
Voltage transients are extremely short-duration fluctuations that stem from load switching, power system faults, or other disturbances within the distribution network.
Transients are difficult to detect unless measurement equipment possesses high sampling rates. Capturing the waveform during a transient provides critical insights into the event's amplitude, duration, and specific characteristics.
For systems experiencing recurring, hard-to-diagnose faults, transient recording capabilities allow technicians to differentiate between incoming power issues and internal equipment failures.
Harmonics, THD, and Equipment Impact
Harmonics typically occur in systems with abundant non-linear loads, such as variable frequency drives (VFDs), switched-mode power supplies, rectifiers, and power electronics. Harmonic components distort voltage or current waveforms relative to an ideal sine wave.
Total Harmonic Distortion (THD) is a key indicator used to assess waveform distortion levels. Elevated harmonic levels increase current draw and thermal losses in conductors, transformers, and electrical apparatus. Capacitor banks are also particularly susceptible when operating in high-harmonic environments.
Harmonic spectrum analysis identifies dominant harmonic orders, aiding in root cause identification and the selection of suitable mitigation solutions.
Voltage and Current Unbalance, and Voltage Fluctuations
In three-phase systems, voltage or current unbalance across phases increases motor current and temperature. For motor loads, voltage unbalance creates negative-sequence components, exacerbating power losses and worsening operating conditions.
In addition to unbalance, rapidly fluctuating loads—such as arc welders or heavy machinery—can cause voltage instability. When fluctuations recur rapidly, voltage flicker becomes pronounced, particularly visible in lighting systems.
Consequently, power quality analysis must concurrently evaluate unbalance levels, voltage fluctuations, and flicker indices—rather than assessing nominal voltage alone.
Power Quality Assessment according to IEC 61000-4-30 Class A
To ensure consistent, reliable measurement results suitable for official compliance evaluations, dedicated analyzers must adhere to standardized measurement methods defined by international standards.
IEC 61000-4-30 Class A specifies measurement algorithms and accuracy requirements for various power quality parameters. Additionally, harmonic measurements and voltage flicker evaluation follow dedicated standards: IEC 61000-4-7 and IEC 61000-4-15, respectively.
Utilizing IEC 61000-4-30 Class A-compliant equipment ensures that test results serve as a rigorous, verifiable foundation when assessing power source quality against technical specifications.
Fluke 1777 – Power Quality Analysis for Proactive Troubleshooting
Fluke 1777 is a three-phase power quality analyzer in the Fluke 1770 Series, engineered for power quality surveys and root cause troubleshooting in industrial environments.
Compliant with IEC 61000-4-30 Class A standards, the Fluke 1777 measures and logs a comprehensive range of parameters: voltage, current, power, power factor, frequency, harmonics, unbalance, flicker, and power quality events.
The device captures voltage transients with ultra-fast sampling rates up to 20 MS/s and a transient voltage measurement range up to ±8 kVpk, recording high-speed events that conventional electrical instruments miss.
By correlating trend data with event logs, technicians can pinpoint precisely when an event occurred, its severity, and its correlation with load operations—providing a concrete foundation for root-cause isolation prior to undertaking deep-level inspections of equipment or distribution networks.
When test results indicate abnormalities in high-voltage equipment, technicians can combine partial discharge detection methods to isolate the source.
Partial Discharge Detection using Acoustic Imaging Cameras
Partial discharge (PD) can occur at locations with degraded insulation or internal defects in transformers, bushings, switchgear, busbars, and high-voltage transmission lines. This phenomenon generates acoustic signals in the ultrasonic range, allowing specialized acoustic imaging cameras to capture and display suspect areas on screen.
Fluke ii915 supports the detection and localization of partial discharge, corona discharge, and surface discharge. The device enables technicians to quickly pinpoint abnormal sources from a safe distance, reducing the need for direct access to high-risk, high-voltage areas. Under suitable conditions, the ii915 can detect discharge sources at distances of up to 120 meters.
=> Register to attend the Seminar to listen to EMIN analyze electrical anomalies and discover power quality monitoring solutions at:
SEMINAR: "Early Detection & Prevention of Plant Failures, Solutions Ensuring Continuous Operation" held on Tuesday, October 27, 2026, in Tra Vinh.
