فارسی
Lighting capacitors

Lighting capacitors are produced under the latest technology and according to IEC 61048/61049 international standard. The dielectric material of these capacitors is BOPP film in different um thickness and the associated electrodes are made of very thin metallic layers (less than 0.3um) which are metallized during a vacuum evaporation process. Any damage in dielectric will cause short circuits between the electrodes and high current will passes through and the created heat around the break point evaporates the metallic layer. After the break down, the short circuit disappears and capacitor continues working automatically. This process is called self – healing which occurs in less than 1/100 seconds. There will be no significant reduction in the capacitance as per the availability of the electrode and the evaporated part.


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

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