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The growing interest in Power Quality is linked to a number of factors:

  • in recent years, some types of loads have spread, such as electronic ones, very sensitive to disturbances;
  • the massive use of electronic converters has led to a considerable increase in voltage disturbances;
  • companies are very sensitive to disruptions caused by poor Power Quality due to the negative impact they can have on profits;
  • sophisticated measuring devices and powerful data processors are now available which have facilitated the detection of various disturbances;
  • when electrical systems are characterized by availability and reliability, quality becomes an achievable goal.

IREM can provide a complete range of products dedicated to the protection of electrical consumers from problems caused by disturbances in the electricity grid.

Voltage variations

Voltage variations can be distinguished in “slow variations” (voltage drops caused by under dimensioned lines and overloads), “over-voltages” (considerable increases of the mains voltage arising when industries drastically cut down their energy consumption), “fast variations” (drops caused by the connection of equipment such as: discharge lamps, punching machines, electric motors etc.). All these conditions negatively affect Power Quality.

Voltage spikes

These are very brief pulse disturbances whose voltage values may reach thousands of volts. They are caused by several events, like e.g. switching of high voltage lines, connection of power factor correction capacitors, lightning, disconnection of loads with high reactive powers, photocopy machines and air conditioners. They are one of the main causes of a poor Power Quality and consequently of failures and disruptions.

High frequency disturbances

They are caused by the sparks generated in the AC commutator motors, by the “corona effect” on the high voltage lines, the igniters of luminous signs and burners, and by the magnetic fields irradiated by radio and TV stations. Line noises are often harmful to electronic devices and do not allow a high level of Power Quality to be maintained.

Harmonic distortions

They are caused by the ever-increasing use of electrical equipment with non-linear absorption such as: rectifiers, converters, drives, switching power supplies. This fault can cause heavy overloads on lines and transformers, explosion of power factor correction capacitors, incorrect indications on measuring equipment and, generally speaking, a noticeable lowering of the Power Quality and consequently the malfunctioning of any electrical equipment.


This is the most obvious event (though less frequent) because everybody perceives it. It may happen accidentally on production plants or distribution lines, or it can be programmed to reduce energy consumption. There are also micro-interruptions, which may last between microseconds and a few tenths of milliseconds, caused by short circuits or line switching. These faults are not noticed by electromechanical equipment, but they can cause damage to an electronic equipment. The switching power supplies used in almost any electronic equipment can normally compensate interruptions lasting a few milliseconds. A longer blackout can cause loss of data, program cancellations, system failures and obviously a noticeable deterioration of Power Quality.

Solution: Uninterruptible power supplies (UPS)

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