Disadvantages
of low power factor
Consider a simple supply system diagram as shown. From this diagram, the power absorbed by the load will
be
Lets see what are the disadvantages
of low power factor. The above concept
must be understood clearly as it is used throughout.
∴ 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.
