Calculation of reactive power of electric units

Reactive power of electric units is some kind of quality indicator of work of the electric unit. Respectively, the more the reactant, the worse it affects the power supply system in general, there is the loading of generators of power plants wattless currents. And it and increase in fuel consumption at which the power plant, losses in receivers and networks and voltage drop works. All this causes additional loads of transmission lines therefore it is necessary to increase the section of cables.

Схемы устройств для индивидуальной, групповой и централизованной компенсации реактивной мощности

Schemes of devices for the individual, group and centralized reactive power compensation.

  The closest attention is always paid to reactive power compensation. At all enterprises in metering stations power meters of accounting of the asset and the reactant are installed. According to the statistics, where there is no reactive power compensation, expenses for the electric power can exceed up to 40%. It is the way of power saving.

So it the reactive power and from where it undertakes? The main consumers of reactive power are asynchronous electric motors. In electrical machines the variable magnetic flux is connected with windings. Thereof in windings at alternating-current course the reactive EMFs causing phase lag (fi) between tension and current are induced.

This phase lag usually increases, and the cosine фи decreases at small loading. For example, if the cosine фи alternating-current engines at the overall load makes 0,75-0,80, then at small loading it will decrease to 0,20-0,40. Therefore to put the cursor on the pump with the stock here as it is visible, not relevant. Means, production capacities have to be correctly calculated and correctly loaded.

The low-loaded transformers belong to such category too and have the low cosine (fi). I.e. loading current without compensation of the reactant will be big at the same consumed active power from network.

Application of automatic compensatory installations reduces the consumed current from network in certain cases to 40-50%

Besides, reactive power along with active power is considered by the electric power supplier, therefore, is subject to payment on the operating rates therefore makes considerable proportion of the account for the electric power.

Ways of decrease in consumption of reactive power: reactive power compensation

Принципиальная схема ступенчатого КРМ

Key diagram of step KRM.

The most efficient and efficiently decrease in the reactive power consumed from network is application of installations of reactive power compensation (condenser installations).

Use of condenser installations for reactive power compensation allows:

From everything stated it is necessary to draw the conclusion: the enterprises which work is based on use of capacities of electric motors first of all have to be completed with compensatory installations. Expenses will pay off undoubtedly.

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