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power factor correction help needed


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#1 waseem

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Posted 05 October 2005 - 04:21 AM

hello there. i am a new member and am a little bit confused. i needed some help with the following:

1. the paper calculations suggest that there are no changes in real power but practice shows otherwise. how come?

2. would running running a motor with its rated load, rather then unloaded, improve its power factor?

some one please help, thank you

#2 marke

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Posted 05 October 2005 - 08:23 AM

Hello waseem

Welcome to the forum.

1) Adding power factor correction does not change the current into the motor and so does not alter the power consumed by the motor.
Adding power factor correction will reduce the current drawn from the supply and so will reduce the copper losses in the supply. These will primarily be in the supply authorities circuits, however if there are significant losses in your cables, you may measure a drop in consumption.
If you can measure a drop in power loss in your cables, then they are too small and you will save money by increasing the cable size.
You should not get any appreciable reduction in KWHrs by the addition of PF correction.
2) Operating a motor at full load will icrease th power factor abnove its no load power factor. If you operate an induction motor with nothing attached to the motor shaft, the power factor could be as low as 0.2 At full load it could be higher than 0.9 This is a characteristic of induction motors.

Best regards,

#3 waseem

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Posted 11 October 2005 - 03:05 AM

i thank you kind sir, after posting i had done some futher research and had come up with a similar answer to my questions but you had made it clearer to understand. i thank you again.:)




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