Firstly let me describe about what is capacitor?This device is very common used in electronic and electric application.The main function is to stored and release electricity charge.
It charge and release depend on frequency ( Hz ) of our power supply.Normally around 50 until 60 times per second in alternating current system.
The construction of capacitor basically made from wound layers of metalized polypropylene (dielectric).The element is sealing in a plastic can with a suitable sealing material.
We can see a two metal plates insulated from each others.For oil filled type,it use a PCB`s as a coolant agent,but now almost capacitor is dry type. read more