Answer / martin

This statement isn't entirely correct. Unity is the most
economical power factor. However, it is quite common that
the target power factor when correcting is say 0.98 - this
is to stop the power factor going past unity (i.e leading
power factor) as this is just as bad as having lagging
power factor and is not welcomed by electricity providers.
To combat this problem, automatic PFC equipment is used
rather than fixed banks of capacitors, so that a target
power factor is reached (as close to unity as possible) and
so that a leading power factor is also not achieved.

I can see why this question is being asked because there
seems to be some sort of myth to say unity isn't
economical. If someone can tell me otherwise, i'd be
interested to listen

Answer / ashwin

Yes, the question is not quite right. But assuming it that you are speaking from the initial cost point of view it is costly.
Unity power factor equipments are very efficient so the generation and transmission costs are reduced. But the equipment required to achieve this unity power factor is quite costly. We can use capacitor banks(condensers)as power factor improving as capacitance improves the power factor. But the cost of the capacitor banks is high and its life is also considerably low. So from that point of view it is uneconomical if you plan to use it for smaller requirements. If you plan to you for larger purposes initially it will seem to be costly but over a period of time this unity power factor will prove beneficiary.

Answer / ghanshyam_singh

i think there is no problem with the question, because at unity pf the value of current flowing in the circuit is minimum, thus unity pf is preferred. althrough it's not possible to maintain it.

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