Power Quality: Problems and Solutions Common power quality problems and solutions.

Power Problems Solutions

Effect on Contributing Moderate Equipment Disturbance Factors Low Cost Cost High Cost

Malfunction or Surge: Caused by • Multiple grounds • Unplug electronic • Surge protector • or permanent damage to , or arcing, • High resistance equipment during with fail-safe uninterruptible power electronic equipment when switching neutrals or grounds storms feature to shut off supply large loads on power on failure • Locate equipment • Surge arrestor at or off on different circuits • Isolation main panel and plug- from large motors transformer in surge protector • Improve grounds • Maintain Contactors

Temporary Multiple grounds, high • Unplug electronic • Surge protector • Power conditioner or : resistance neutrals or equipment during with fail-safe uninterruptible power Crossed wires grounds storms feature to shut off supply due to weather power on failure • Improve grounds • Surge arrestor at conditions, trees • Isolation main panel and plug- and vehicle transformer in surge protector accidents

Static Dry weather Improve grounds Humidifiers and static control

• “Hash” on Noise: Interference Poor grounding • Shut off or replace • Noise filters Power conditioner or monitors from small dimmers and (sometimes uninterruptible power • “Static” on radio electrical motors, appliances included in plug-in supply dimmers, • Improve grounds surge protectors) photoelectric cells, • Isolation adjustable speed • Move sensitive transformer drives and other equipment to other devices circuits • Maintain devices causing noise

• Lights dim or blink Sags: Starting • Undersized or • Replace batteries • Constant Power conditioner or • Equipment major appliances, overloaded wiring in equipment transformers uninterruptible power short circuits on unexpectedly • Long and/or • Save data to disk • Locate equipment supply the power lines shuts down overloaded circuit frequently on separate • Monitor displays runs circuits shrink • Computers reset, “Momentaries” Save data to disk Uninterruptible power lose data or (outages up to frequently supply programs 15 seconds): Short circuits due to storms, contractors digging up cables, vehicle accidents

• Equipment power • Single phase: • Overloaded motors Surge protectors • Power conditioner or supplies burn up Failure of or power supplies with undervoltage uninterruptible power one phase • Motors burn up/ • Motor load and protection supply conductor to winding failures fuses/protective • Install phase loss the building or devices are not protection relays on • 1/3 to 1/2 of the equipment lights shut down coordinated motor contactors • Temporary • Circuits overloaded, • Undervoltage relays Undervoltage: high resistance Overloaded neutrals or grounds circuits and equipment failure

pse.com/powerquality