What Happen Capacitor Bank Connected in no load

What happened Capacitor Bank Connected in no load.

In Power system, Capacitors are nothing but source of reactive power. It used to deliver reactive power to the load. In this article, we are going to see what will happen when capacitor bank is connected on the No load condition ? Let see.

Capacitor are used to maintain power factor in the electrical power system. During lagging power factor the reactive current goes to the load and , for leading power factor the load delivers reactive power (since the direction of current reversed). Since they deliver reactive power to the load during load condition and they pump reactive power as it designed capacity. i.e if you install a capacitor bank of 32kVAR means, it should deliver 32 kVAR Reactive power to the load (irrespective of the load condition) typically, it delivers the prescribed reactive current as it designed. Now consider Load has been stopped for a while, then the capacitor does not stop pumping reactive current to the load


Note: The voltage across the capacitor must be present.

But in our case the load is isolated or reduced (the requirement of reactive power is reduced) since the reactive current (The reactive power) goes to the source..because once capacitor bank is connected to the source then the capacitor starts injecting reactive power irrespective of the load. You get leading power factor,which means the source aborbe the reactive power from the capacitor bank. or the reactive power injected by a one feeder will be absorbed by another feeder. In worst case, absence of nearby loads the source voltage rises abnormally..or if you connected with the grid, your capacitor bank starts delivering reactive current to the grid loads.In generator one protection “Reverse reactive power protection” is used to protect such condition…

Reactive Power flow on No load
Reactive Power flow on No load


 

Refer the diagram of the reactive current flow to the load when the load is connected (red), The green path shows the flow of reactive current to the source during no loads (It goes to the source as well as grid)

Since when you connect the capacitor on no load, the reactive power should be consumed by nearby feeders, otherwise the source may affected by series voltage rising issues.

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