Does Power Quality Matter?

As technology advances, electric power usage is moving from simple, non-electronic loads (tungsten lamps, motors, relays, resistive heaters, etc.) to more complex ones (fluorescent lamps with energy-efficient ballasts, motors with solid-state drivers, personal computers and home appliances) with more detailed electronic components in them. The electric current drawn by these new devices is typically different from that of the predecessors, and causes problems in overall capacity of the electric utilities.

Most power quality issues result in performance, safety and overheating problems. In particular, power distribution polluted by harmonic can lead to:

What is Power Quality?

Power quality (PQ) is a multi-dimensional and complex measure, especially as it applies to AC power circuits. PQ encompasses voltage, current, power factor and frequency spectrum magnitudes. It can involve electromagnetic field measures. Sudden or gradual changes in any of these measures have a big impact on power quality. PQ is really a comparison of the actual to the ideal or desired values of each of the characteristics of electrical power. Unlike current or power, which are measured in amperes and watts there is no scoring or measurement unit for PQ. Consequently, terms associated with power quality refer to the gaps or anomalies between the actual and desired values. Desired attributes of PQ are therefore negative terms; no dips, no spikes, no sags, no surges, no outages, etc.

Type of Power
Quality Issue


Causes – Effects

Voltage Drop/Flicker

Causes: starting or stopping of big loads, such as an air conditioner compressor or a big motor, or equipment that draws current intermittently.

Effects: loss of data, overheating of motors, unexpected equipment resets and poor / uneven visibility (flicker).

Reduction of

Power Factor

Causes: addition of excessive capacitive / inductive loads, fault in capacitor filters or compensation system.

Effects: greater operating costs, penalty charges in electricity bills.

Harmonic Distortion

Causes: non-linear loads (in almost all electronic equipment or drives).

Effects: overheating of electrical equipment, wiring and motors, automatic switch malfunctions, tripping of relays, opening of fuses and a general reduction in the efficiency of the system.

Imbalance on

Three-phase Load

Causes: connected single-phase loads with different powers, three-phase load faults.

Effects: inefficiencies, overheating, motor and transformer faults.

Transient Current /

Over Voltage

Causes: switching of filter condensers, switching large equipment on and off, short circuit in wires or a lightning discharge.

Effects: shorter lamp life, equipment stopping / damage, PC crashes with memory loss, data processing errors, printed circuit card burnouts and motor and transformer insulation damage.

How do we conduct a power quality analysis service

Before performing an onsite survey, it is important to review your facility’s power system performance. This preliminary analysis characterizes the problem, identifies important changes to the facility or to the electric supply system (equipment or wiring changes, modifications, etc.) that could be causing power quality problems, and helps determine a plan for the site survey. Consisting of a conference call, this preliminary review sets the stage for the site survey. In fact, we can sometimes diagnose current or potential problems at this stage, thus reducing the need for or scope of the onsite survey and helping to focus attention where it is most needed

The site survey is designed to gather information about the facility, power quality problems, and affected equipment. Field measurements are completed in conjunction with the onsite power system and equipment inspection. A wide range of power characteristics and disturbances are monitored and recorded:

  • Voltage regulation
  • Phase voltage imbalance
  • Total connected load current
  • Power transformer detailing
  • Frequency regulation
  • Phase rotation
  • Power factor
  • Line disturbances
  • Voltage & current total harmonic distortion
  • Crest factor
  • Phase symmetry

Following the preliminary review and site visit, we will prepare a technical report summarizing the findings of the audit. This report will include a summary of all of the information gathered, highlighted power system problems, a summary of field measurements, suggested solutions, and recommendations for follow-on power system monitoring or engineering analysis. This report introduces you to the scope and nature of any problems, and provides an excellent foundation for more analysis and effective power system design.

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