Common Power Quality Problems

27 01 2012

Top 5 signs of a power problem:

  • Repeated equipment failure
  • Random equipment resets or process failures
  • Breakers tripping or fuses blowing with no signs of overloading
  • Transformers or motors running hot
  • Uninterruptible power supplies frequently going on line

What’s causing these problems?

  • Voltage dips and swells - Caused by large loads starting up or shutting down. Damages computers and electronic controls.
  • Harmonics distortion - Corrupted electrical waveforms, seen in the current frequency cycle. Causes heat-related problems in motors and transformers, plus problems with circuit breakers, fuses and relays.
  • Voltage unbalance - In 3 phase systems, when voltage between phases differs by more than 2%, motors and transformers overheat.
  • Flicker - Cyclical voltage dips cause lights to flicker.
  • Transients- These brief, sharp voltage increases are caused by equipment switching on/off, capacitor switching, and lightning, and can lock up computers, burn out circuit boards, and damage electrical insulation.

The purpose of a power quality survey is to assess whether the power in your facility is pure enough to reliably support the required loads at optimum performance and at a reasonable price per kWh. Power disturbances can involve voltage, current or other parameters and typically manifest as dips, swells, harmonic distortion, unbalance, flicker, transients, and additional power factor or peak demand fees on monthly utility bills.

More than 80 percent of all power quality problems originate within your facility.

Common culprits are:

  • Large equipment starting-up or shutting down
  • Improper wiring and earthing
  • Overloaded circuits
  • Harmonics

Less than 20 percent of power problems originate with the utility transmission and distribution system. Lightning strikes, equipment failure, accidents, and weather conditions all adversely affect the utility. Neighboring businesses and normal operation of utility equipment can also aect the quality of power delivered to your facility.

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