Harmonics Study, Analysis and Solutions

Harmonics


Overheating Transformer


Overheating Transformer


Thermal Image of overheating


  • Do they exist at my facility?
With increasing use of non-linear loads the power systems are getting highly polluted by harmonics which is leading to premature failures of electrical and electronic equipments as well as nuisance tripping leading to production loss. So it is imperative that a study of power quality of the electrical distribution system of a plant should be made to assess the level of pollution due to harmonics and adequate measures should be taken to control it.
  • Variable Frequency Drives (VFD/VSD)
  • UPS and SMPS
  • LED lights
  • Electronic Ballast
  • The standard which is used to deal with the harmonic limits on the system is IEEE 519-1992.

  • What is Harmonics?

A pure sinusoidal voltage is a conceptual quantity produced by an ideal AC generator built with finely distributed stator and field windings that operate in a uniform magnetic field. Since neither the winding distribution nor the magnetic field are uniform in a working AC time relationship deviates from the pure sine function.

The distortion at the point of generation is very small (about 1% to 2%), but nonetheless it exists. Because this is a deviation from a pure sin wave, the deviation is in the form of a periodic function, and by definition, the voltage distortion contains harmonics.


  • Major Equipment effected
    • Electric Motors
    • Transformers
    • Capacitor Banks
    • Cables
    • Neutral

  • Negative Effects of harmonics
Voltage Harmonics Current Harmonics
Malfunctioning of sensitive electronic equipment Increase in resistive and hysteresis losses and attendant temperature rise in the winding and cost of the supply transformer
Premature ageing of such equipment Nuisance tripping of electronic protection relays and circuit breakers
Increase EMI generated in the power system Failure of power factor correction (PFC) capacitors due to series or parallel resonance in the supply system
Increase in core losses in motors which are directly operated from the utility supply Increase temperature rise in connecting power cables
Increase torque ripple in drive motors directly operated from the utility supply Failure of the neutral current carrying conductor in the supply transformer due to unbalanced single phase non-liner loads

  • How do I get them measures

Pima Energy can carry out a Harmonics Study at your plant. We come with our own hi-tech measurement equipment to get accurate information.


  • What do I do when I know I have them?

If they are within the IEEE 519 limit, then you have nothing to worry about. In case harmonics are higher than the limit, they will be demanding your equipment as stated above. Pima Energy can provide you a guaranteed solution to mitigate the harmonics to the define levels.



Pima Energy Methodology