Power Quality ......What is it?

Defining power quality is very difficult. If the user can power the specific equipment with the power that is available then it is generally felt that the quality of the supply is suitable for the task. However if the equipment fails to operate reliably from the mains supply its referred to as "Dirty" or bad and it has to be cleaned or a clean supply obtained.

In general the generated electricity at the power plant is clean with a waveform that is sinusoidal and a frequency of 50Hz (60Hz in some countries) the only exception being breaks produced by equipment failure or adverse weather conditions. It is normally the users loads that cause power quality problems.

The electric power we all take for granted whether its generated by coal, nuclear, gas or hydro is still produced by large electrical machines (alternators) which essentially have not changed in the last 50 years. The technologies used to control, measure and to transmit energy has improved but the flow of the electric current is still dependant on the same laws of physics.

Any load when connected to the AC supply will consume energy that is dependant on its apparent impedance or resistance and that of the supply path (ohm's law). There is at present no known cost effective technology that can store AC power which means that it is possibly the only product that has to be produced at almost the instance that it is required to be consumed.

This problem of immediate production and use together with the interconnected nature of the transmission system (the grid) means that all users large or small are effectively connected in parallel with each other and any large disturbance that is generated by one user will be propagated via the transmission system to all the other users.

Typical power quality issues are: sags, surges, spikes and power failures all these disturbances are created by modification to the amplitude of the AC waveform and can be detected by basic measuring instruments and removed with voltage stabilizers, conditioners and UPS systems. The only other issue in the past was that of "Power Factor". This is the displacement of the current waveform in time with respect to the voltage waveform caused by motors, transformers and fluorescent lighting systems. This was normally and still is overcome by connecting large capacitor banks across the supply.

In the past the major loading of the supply system was made up of large slowly changing electrical loads like motors and transformer systems which were linear in nature, i.e., the current that they consumed was directly proportional to the supply voltage. The current waveform being sinusoidal with the only power quality problem being that of power factor.

Over the last ten to fifteen years the gradual and never ending proliferation of computers, micro processor systems and power electronics in all kinds of industrial, commercial and domestic facilities has completely changed the nature and profile of the supply loading.

These new electronic technologies rely on the conversion of the AC supply to DC, this process (until recently) has been very non-linear and produced high levels of odd harmonics in the supply current.

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In order to assist you from your critical power quality situation, we are having a few solutions which might be suitable to restore the situation depend on it's level.

• Blocking Reactor

Please do not hesitate to contact us should you required further assistant.