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When loads are different, their power factors are also different. Some of those are:
It is explained via,
As per this,
[Current kVA]
Various causes regarding low power factor
- Operation of arc lamps because of its typical characteristics leads to low power factor.
- Low lagging power operation in in induction furnaces and arcs
- All transformers and A.C. motors functions at straggling power factor. Some exceptions are- few Commutator motors typesand certain overexcited synchronous motors.
- During periods of low load when the supply of voltage is high, in inductive reactance magnetizing currents increases which lead to a decrease in power factor.
- Improper maintenance and lag in motor repair
Result of poor power factor
- A huge power drop is observed when a load comprising low lagging power with ample current supply is switched on. This drop is with respect to voltage This is due to a hike in voltage drop in transformers and supply lines. An adverse effect is observed due to this voltage drop on starting torque of motors. This creates the situation to utilize costly voltage stabilizing equipment to keep voltage fluctuation of main equipment within limits.
- To keep power factor to its minimum, it is required that more current is supplied and carried out by cable or distributor or transmission line. In order to keep the current density at constant within the line, it is required that conductor size should be increased. So the resultant is lower power factor but with requirement of more copper for similar load delivery.
- [Transformers and alternators’ ratings (proportional) output current]
Power factor is inversely proportional to the above equation. Hence, same load delivery by transformers and huge generators at a lower power factor.
- In case of a bus bar, its cross-sectional area, as well as a switch gear’s contact surface, should be of large proportion. This is a necessary requirement as similar power is required to be delivered except at lower power factor.
- The proportionality of square of current is with respect to copper losses. This in totality is seen to be inversely proportional to power factor’s square root. This in simplified form means that at lower power factor, higher is its copper losses. This as a resultant contributes to poor proficiency.
So, it is clear that capital costs regarding alternators, transformers, transmission lines, distributors, and much more, when increases; we can see a decrease in power factor.
Improving techniques regarding power factor
5 of the important techniques are as follows:
- Utilization of synchronous condensers
- Utilization of capacitance boosters
- Utilization of static capacitors
- Utilization of induction motors in addition to phase advancers
- Utilization of high power factor motors
Links of Previous Main Topic:-
- Current Electricity Basic Concepts
- Introduction to Alternating Current
- Introduction Three Phase A C Circuits
- Advantages of Polyphase Systems
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