Quick guide to power quality symptoms and causes

Power quality

To the untrained eye, problems in electrical distribution systems or the equipment connected to the circuit may not be recognizable as power quality problems. When no immediate problem is apparent, it may be written off as just an old breaker that needs replacing or a one-time nuisance reset. You might look at types of loads on the system and monitor for harmonics, unbalance, or disturbance patterns.

Power quality measurements show different problems in chart form.

Harmonic distortion issues and voltage and current anomalies represent the areas where common problems in power quality occur. Voltage and current anomalies can produce problems; however, many can be corrected before they damage equipment. Spot the symptoms:

IssueSymptomsPotential causes
Dips or SagsLighting dimming, computer lockups, relay and contactor chatter or complete dropout, equipment and system shutdowns
Spurious and unexplained alarms and shutdowns
Starting large loads, especially large inductive
Similar operations in neighboring facilities
Severe weather
SwellsFailed power supply
Overvoltage shutdowns and alarms on variable frequency drives (VFDs)
Fault on single phase of three-phase system
Sudden load decrease
Capacitor bank switching
TransientsFlashover and arcing effects in distribution equipment
Damaged insulation
Failed electronics
Computer lockups
Lightning strikes
Switching of capacitors
Reenergizing systems after a power failure
Sudden stoppage of large equipment
Dirty or worn contactors
InterruptionsEquipment shutdownsMomentary loss of utility power
UnbalanceOverheated three-phase motors and transformersUnbalanced loads across individual phases of three-phase panelboards
Unbalanced utility supply
Operation of single-phase welders
Open-delta transformers
HarmonicsOpen-delta transformers
Overheated transformers
Overheated inductive motors
Spurious and unexplained alarms and shutdowns of electronic equipment
Nonlinear loads such as switching power supplies
Converter sections of uninterruptible power supply (UPS), VFDs and battery chargers
Arc furnaces

Power quality analyzers and loggers

A Power Quality Analyzer can help to recognize these common power quality problems. You’ll never miss a critical power quality event with a power quality analyzer. Whether you’re performing a quick system check or a detailed power quality study, consistent data is key. Plugging the 1770 series into your assets, the tool offers a unique automatic measurement capture system that helps ensure you’re collecting the right data every time—from fast transients up to 8 kV, harmonics up to 30 kHz, dips and swells, as well as the voltage, current, and power measurements that enable you to characterize problems in your electrical system.

Power Quality Loggers make it easy to profile energy usage in your facility. They deliver power-measurement data so you can discover and mitigate sources of electrical energy waste or overloaded circuits. These tools are great to have in-hand for routine load studies and preventive maintenance programs.

Power Quality Recorders are the tool to grab for advanced power quality analysis. Uncover the root cause of equipment malfunctions with load studies and transient analysis so you can later go back and make necessary repairs or develop baseline information for routine load studies.

Electrical measurement windows

Electrical Measurement Windows are an additional tool to make measurements with these tools easier. An electrical measurement window is permanently installed into the face of a cabinet with the necessary connections ready to go. Instead of having to open the cabinet, you can just take measurements at the window, making it a safer process for routine preventive maintenance or load studies.

Find the right power quality tool

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