Application:
To switch on all kinds of gas discharge lamps (like fluorescent, mercury vapor, sodium vapor, halogen & similar types) a reactor or transformer is needed. Since these reactors/ transformers create inductive load, they increase the current and decrease the power factor (Cos 0) to 0.5. power factor correction to 0.9 is made by adding suitable capacitor to the circuit.
Parallel compensation (adding capacitor parallel to power supply) is more frequently in use than other methods due to the following reasons:
1) Easy installation
2) The voltage of capacitor teminal is equal to supply voltage
3) Interruption of capacitor doesn’t affect the circuit.
It shall be noted that because of poor cooling in lighting circuits and capacitor closeness to power supply, the capacitor will be exposed to high temperature for a long time.
Advantages of self – Healing capacitors:
1- low dissipation (Max. tgd is 20
*10-4)
2- No permanent short circuit because of self – healing
3- Smaller dimension and lower weight
4- Free from any leakage and environmetal pollutant materials due to dry type resin . (NON – PCB)
5- Lower price
|