Power Factor
Power Factor
(OP)
Please explain why the utility power company limit at 0.9 PF for the Genset system co-gen producer.
Thanks
Thanks
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RE: Power Factor
RE: Power Factor
RE: Power Factor
Thanks
RE: Power Factor
I always believed that 0.95 or 1.0 was more than 0.9 and this is confusing me. I would expect 0.9 to be the minimum, not the maximum.
If you are involved with co-generation there must be someone in your organisation who understands power factor and can help you.
I enjoyed Zogzog's graphic description, but it may now be in doubt.
yours
RE: Power Factor
Therefore, the smaller the (leading) power factor, the greater the reactive power being delivered by the cogen rather than the utility.
RE: Power Factor
RE: Power Factor
Excuse me. I have a communication problem with the forum. I do not know why. any way,
To answer of your question particularly to Davidbeach, I do not have information regarding the utility contract. This question came to me a long while ago when a friend asked me why the utility limit the PF at .9 maximum. That all I knew. I did not have the good answer to him so so why I reapeat this question again hoping that you shoud give me the idea.
Thanks all
JPEELECTRICAL
RE: Power Factor
Please accept my apology for my previous flipant answer.
The utility charges a penalty when the power factor falls below 0.9 or 90%
90% is the minimum, not the maximum.
If the power factor is poor they must transmit more current to deliver the same power.
A simple example would be two loads side by side, one at 100% power factor and the other at 50% power factor.
If they are both using the same amount of Kilowatt hours, the load with 50% power factor will be drawing twice as much current. That means that the transformers, switches, cables, and generators must be twice as large so as not to overheat.
However, the revenue from both loads is based on kilowatt hours, and is the same.
Because of the added costs of supplying bigger equipment to cope with the poor efficiency of a poor power factor, the utilities charge a penalty if the power factor is poor. The figure of 0.9 or 90% is common but by no means the only figure. Some states in India charge a penalty if the power factor drops to 99%.
The actual ammount of the penalties also is subject to variation.
respectfully
RE: Power Factor
RE: Power Factor
RE: Power Factor
I agree with your def'ns in your 'quibble', but I used a 'load-centric' rather than 'generation-centric' viewpoint to make my point (which is why I took care to mention 'furnishing VAR's' to be clearer to all).
After all, it's the utility's perspective that counts, since they are setting the rules. At my utility, we treat embedded generation more like 'anti-loads', so that we can talk about leading, lagging, real, reactive, etc in only one set of terms to avoid confusion. Maybe if we owned generation, we'd be more careful to match IEEE terminatology! ;)
RE: Power Factor
Okay, thanks for the correction. If the utility requires the generator to produce lagging vars in relative to the real power being supplied, then the requirement may be made expressed as a maximum pf. A minimum reactive factor of .436 might be a better way to express the requirement, but power factor may be more widely understood.
RE: Power Factor
I have found that there is a much better definition of leading and lagging that doesn't require knowing whether you are dealing with a load or a source - if watts and vars are flowing in the same direction, the circuit is lagging while if the vars and watts flow in opposite directions, the circuit is leading. That works for loads and generators and does not require any distinction between the two.
I know there was a discussion a while back as to whether or not vars actually have direction. Maybe they do, maybe they don't, but using the same definition for direction of power you can get a workable definition of direction for vars and that works well for this.