APPLICATIONS OF CAPACITORS

1. Industrial Applications:-

Capacitors are installed in industries for the improvement of power factor, improvement of voltage, reduction  in energy loss, etc.

2. Switching with induction motors:-

Capacitors are generally applied to induction motor terminals, to help them during the switching on period. 

Of course, while using this technique, certain precautions are necessary, and a suitable size of the capacitor has to be determined for different motor ratings,

3. Series induction:-

In order to improve the voltage regulation of a line, a capacitor is used in series with the line to compensate for the line reactance.

4. Induction heating:-

Capacitors are extensively used in heating for supplying exiting current to induction heating equipment.

5. Miscellaneous applications:-

Capacitors are also used in resistance-type welders to compensate for the welder reactance, and to improve the power factor.

Induction accelerators used in nuclear research, such as Betatrons and Synchrotrons, require excitation for large a.c. magnets.

Capacitors are also used in florescent ballasts for improving power-factor, as by-pass capacitor and blocking capacitors in electronic circuits.

For storage of energy such as in welding and flash photography.

CAPACITANCE AND CAPACITOR

If a potential difference V is applied between two conductors (or plates) placed closed together but insulated from each other, to produce charges +Q and -Q upon them, there is proportionality between the charge and the potential difference,  which is expressed as:

Q ∝ V

or    Q = C ᐧ V

where C is a constant called the Capacitance of the particular set of mutually insulated conductors, their distance apart and on the nature of the insulating material, between them. The insulating material is called the dielectric.

Such a construction of two conducting bodies (whether in the form of plates or spheres) placed close to each other but separated by an insulating material from each other is called a Capacitor or Condenser, and is used for storage of electrical energy.

From the above relation, the capacitance is given by:

C=QV

The charge Q is expressed in coulombs, the potential difference V in volts, then the capacitance C is expressed in farads.