By Jason Axelson, Fluke Subject Matter Expert, Power Quality
Unlike slow-developing electrical issues, transients are fast and elusive. Diagnosing them requires the correct tools and a strategic approach.
Consider these real-world electrical mysteries as true Sherlock Holmes-style whodunits.
At an unnamed manufacturing facility, a large three-phase motor strangely experienced repeated failures over a three-year period. The motor was replaced. Wiring was inspected. But the failures kept returning. Despite interventions from both the electrical contractor and the motor manufacturer, the root cause remained elusive.
Similarly, at Crystal Mountain Resort in western Washington, the state’s largest ski resort, two power filters associated with chairlifts failed catastrophically. The filters were rated correctly, and no obvious electrical fault was visible. The failure was not identified after the ski season had ended and, fortunately, no skiers were affected. But it was puzzling, nonetheless.
In both instances, it took a deeper investigation by Fluke’s power quality analyzers to “solve the case.”
The hidden culprit? Electrical transients — brief, high-speed voltage events that strike without warning, leaving damaged electronics, corrupted data, and costly downtime in their wake. By identifying and addressing these transients, each facility was able to prevent further equipment damage and reduce downtime. (See the links at the end of this article to learn more about each case.)
Unfortunately, electrical transients have become more common than we’d like. They’re often invisible to the naked eye and overlooked in standard troubleshooting. Yet they can quietly erode the reliability of your entire operation.
In this article, we’ll explore what causes transients, how to detect them, and most importantly, how to stop them before they ravage your bottom line.
So, Just What Are Electrical Transients?
Power system transients are short-duration surges in voltage or current that can occur from internal or external sources. They're typically classified into two types:
- Impulsive transients – sudden, unidirectional spikes caused by events such as lightning or electrostatic discharge.
- Oscillatory transients – rapid, bidirectional voltage fluctuations often caused by switching inductive loads or capacitor banks.
Electrical transients occurring from external sources can include events such as lightning strikes, utility grid switching (e.g., capacitor bank operations), and short circuits on the supply side.
Those occurring from internal sources are often related to facility operations and equipment. Common culprits include load switching, variable speed drives (VSDs), faulty breaker contacts, light dimmers, and arc welders. Even internal short circuits can generate significant transients within the system.
Though they last only microseconds to milliseconds, their effects can be devastating. Sensitive equipment such as PLCs, VFDs, sensors, and industrial PCs are especially vulnerable. Repeated exposure — even to low-magnitude transients—can degrade components over time, leading to:
- Premature equipment failure
- Data corruption or communication errors
- Unexpected downtime
- Increased maintenance costs
- Safety risks in critical operations
Diagnosing the Invisible: How to Detect Transients
Unlike slow-developing electrical issues, transients are fast and elusive. Diagnosing them requires the correct tools and a strategic approach.
Step 1: Use a Power Quality Analyzer
Start by deploying a high-speed, high-resolution power quality analyzer capable of capturing transient events. Instruments such as the Fluke 1775 or 1777 Three-Phase Power Quality Analyzers are specifically designed for this task, because they feature built-in transient capture, logging, and waveform analysis.
Step 2: Measure at the Right Locations
Begin your investigation closest to the equipment that's failing, then work upstream toward the service entrance. This helps you localize the transient source — whether it's internal or coming from the utility.
Step 3: Identify Common Sources
Transients can come from sources such as these:
- Internal: switching of motors, transformers, or variable frequency drives; arc welders; or poor grounding.
- External: utility grid switching, capacitor bank operations, or lightning (even indirect strikes).
Step 4: Analyze Key Data
Power quality analyzers can capture transient data including:
- Voltage magnitude
- Event duration
- Frequency and waveform shape
These parameters help classify the type of transient and guide the appropriate mitigation strategy.
How to Prevent Transients from Taking You Down
Once you've identified the problem, the next step is mitigation. Here are proven solutions:
- Install Transient Voltage Surge Suppressors (TVSS): These are your first line of defense. Choose surge protection rated for your system’s voltage and application environment.
- Use Filtering Technologies: Depending on the type of transient, install appropriate line filters, isolation transformers, or RC snubbers to dampen or redirect energy spikes.
- Improve Grounding and Bonding: Poor grounding amplifies transient effects. Audit your grounding system to ensure continuity and low impedance.
- Engage the Utility Provider: If you suspect utility-side transients, coordinate with your provider for a power quality review.
The Bottom Line: Reliability Starts with Visibility
Electrical transients don’t just break equipment — they break trust in your facility’s reliability. By proactively identifying and mitigating them, you can extend asset life, reduce downtime, and protect your operational efficiency.
Fluke’s line of power quality analyzers, including the Fluke 1770 Series, provides facility managers and maintenance engineers with the visibility they need to catch transients in the act.
About the Author
Jason is a subject matter expert at Fluke specializing in power quality, electrical test equipment, and product applications. With deep experience supporting both customers and distribution partners, he helps professionals select, operate, and troubleshoot a wide range of diagnostic tools—including power quality analyzers, battery testers, acoustic imagers, and thermal imagers. Jason regularly leads application-based training sessions, drawing on his hands-on knowledge to bridge the gap between technical challenges and practical solutions across industries. Connect with Jason on LinkedIn.