Effect of Lagging Power Factor
Effect of Lagging Power Factor
(OP)
I am an engineer (mechanical) at a paper mill and I have been wondering about the consequence of have a lagging power factor on the downstream equipment (breakers, starters, cabling, motors etc.)? If I am to believe the the meter on the incoming breaker for one of the four feeds from the utility it is reading 0.5 lagging. This feed has only inductive motors and 8 DC motor drives. There are no capacitors or synchronous motors on this feed.
I realise their maybe a penalty (I need to research if there is one as no one has complained about the bill) from the utility for a poor power factor. I am more interested in the effect on the equipment.
Thanks in advance for any advice
I realise their maybe a penalty (I need to research if there is one as no one has complained about the bill) from the utility for a poor power factor. I am more interested in the effect on the equipment.
Thanks in advance for any advice






RE: Effect of Lagging Power Factor
RE: Effect of Lagging Power Factor
Each load will have its own power factor based on the type of load. This has no impact on other equipment.
RE: Effect of Lagging Power Factor
You may improve the power factor of the circuit feeding an induction motor but the power factor of the motor will remain the same. A cheapest and easiest first responce will be to add capacitors to each large motor to correct the motors to unity power factor. If there are no complications you may connect the capacitors to the load terminals of the motor starters.
Caution, do not restart motors with capacitors connected until the residual current has decayed.
If you have a large number of small induction motors you may have to use a switching power factor correction scheme.
respectfully
RE: Effect of Lagging Power Factor
If the utility has to make their system bigger to accomidate you system, they may charge you for the KVA they have to have to handle your load.
http://www.nakahoma.com/POWER_FA.PDF
RE: Effect of Lagging Power Factor
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RE: Effect of Lagging Power Factor
A motor doesn't care about the power factor of the system it's hooked to... it only cares about the voltage (which might be influenced by power factor as a second order effect mentioned by dpc)
A breaker or cable cares about the power factor of the load flowing through it becuase a given kw at lower power factor means a higher current and higher I^2*R heating
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RE: Effect of Lagging Power Factor
Now comes the fun part, convincing management the need to address the problem.
Thanks
RE: Effect of Lagging Power Factor
some time if you have load expension adding cap can prevent changing cables so $$
over here if your TOTAL power factor is below .95 the electrical company charge a big extra for it
RE: Effect of Lagging Power Factor
Capacitors can be a real headache, though. Especially if they start exploding or blowing fuses or causing harmonics problems.
RE: Effect of Lagging Power Factor
RE: Effect of Lagging Power Factor