What is KiloVAr Control

KiloVAr Control

• KiloVAr sensitive controls (Refer figure A) are used at locations where the voltage level is closely regulated and not available as a control variable.
• The capacitors can be switched to respond to a decreasing power factor as a result of change in system loading.
• This type of control can also be used to avoid penalty on low power factor by adding capacitors in steps as the system power factor begins to lag behind the desired value
• Kilo Ar control requires two inputs-current and voltage from the incoming feeder, which are fed to the p.f. correction mechanism, either the microprocessor or the relay.
• Due to change in the system loading p.f. changes then capacitor is switched on.
• This meter control avoids penalty due to poor p.f.
• There are two inputs i.e. current and voltage from incoming feeder.
• This is fed to power factor correcting mechanism (may be a relay or microprocessor).
• When the load is low, the effect of capacitors is more pronounced and may lead to hunting. Under current blocking shuts off the relay, switching off all capacitors one by one in sequence, when load current is below setting.
• Special timing sequences ensure that capacitors are fully discharged before they are switched in. This avoids dangerous over voltage transient.
• The solid state indicating lamps (LEDs) display various functions that the operator should know and also indicate each capacitor switching stage.

Figure A

Intelligent Power Factor Controller (IPFC) :

• This controller determines the rating of capacitance connected in each step during the first hour of its operation and stores them in memory.
• Based on this measurement, the IPFC switches on the most appropriate steps, thus eliminating the hunting problems normally associated with capacitor switching.
• Due to change in the system loading, p.f. changes then capacitor is switched on.
• This meter control avoids penalty due to poor p.f.
• There are two inputs i.e. current and voltage from incoming feeder.
• This is fed to power factor correcting mechanism (may be a relay or a microprocessor).

Main components of this controller circuit are :

   (6) Bus-bar.

• Controller unit senses voltage and current.
• If p.f. falls to lower value then targeted capacitors are sequentially switched and these are controlled by relay unit. Relay is the important element in such controller. It sends signals to capacitor switching ON/ OFF.

Figure B