Disadvantages of Low Power Factor | why Power factor should be improved ?

Disadvantages of low power factor

disadvantages of low power factor


Consider a simple supply system diagram as shown. From this diagram, the power absorbed by the load will be 
disadvantages of low power factor

Lets see what are the disadvantages of low power factor. The above concept  must be understood clearly as it is used throughout.

disadvantages of poor power factor
∴  to supply load of given kw rating, the kVA supplied by the alternator must be more for low power factors ∴  making the equipment  larger and expensive. Same is true for transformers and switchgears as they are also rated in kVA.

(2) Greater conductor size :- To supply given P at constant VL  , the supply lines will have to carry more current at lower power factor   ∴  large size conductors will be required.


(3) Larger ohmic losses :-  As ohmic losses depend on current magnitude squared  ( I2R )   ∴ there will be more losses in alternators ,transformers, switchgears ,transmission lines etc.

(4) Poor voltage regulation :-  As current increase with decreasing power factor, there will be greater voltage drops in alternators, transformers, transmission lines etc. resulting into decreased voltage available at the supply end, thus impairing the performance of devices connected. 


All the mentioned effects either increases the losses for power companies or force them to install larger kVA alternators, thereby capital investments for power companies are increased and that is why power companies penalize its customers for low power factors. These disadvantages advocates the need for power factor correction.


Closely related concepts :-
   (1) Power factor correction methods