Increase my pf

[puckman]

In a industrial plant [480v] where the power factor is never above .7, not sure if plant is charged for low pf. Is the idea to increase the pf at the service or must it be done throughout the plant first to have any inprovement ? We are thinking about hiring contractor to look into this for us but we like to get as much input as we can first to get a better understanding of what is involved.

Looking for some information about this either personel experience or maybe internet help.

 

[don_resqcapt19]

The first thing you need to do is to find out if you are being charged a penalty for the low power factor. If not you will not save much by improving the power factor. Without a penalty the only chance for some small savings is to put the power factor correction at the loads. There will be a slight reduction on the I^2R losses when you correct the PF, but this will not change much on the watt hours used.

 

[beanland]

I Agree

I Agree

If thereis no PF penalty charged, there is little economic incentive to fix the pf. If there is a penalty, you need to find out if the utility penalty is for lagging pf and/or leading pf, too. Many industrial customers with poor pf just add one big cap bank at the service. That is generally the cheapest solution. If you have transformer capacity issues, installing caps on the secondary of the transformer can reduce loading and losses. Losses in wire are seldom worth fixing. Installing caps all over the facility is the most expensive approach.

 

[rafael rivera]

Another Solution

Another Solution

Depending on the size of the facility and equipments involved you can install a Synchronous Motor to drive; let say a compressor and at the same time improve your plant wide PF. There numerous motor repair companies the keep a good inventory stocks of this motors that have been recondition and they provide you with warranties; so you don't have to make the expense of purchasing a new one.

 

[robbietan]

one approach would be to identify the causes of the poor pf - and either replace them with hi-efficiency models or install a cap at the load (for olde motors).

but better off checking how much penalty the place is paying for low pf. it is usually the starting point of capacitor installers

 

[mivey]

The first thing you need to do is to find out if you are being charged a penalty for the low power factor. If not you will not save much by improving the power factor. Without a penalty the only chance for some small savings is to put the power factor correction at the loads. There will be a slight reduction on the I^2R losses when you correct the PF, but this will not change much on the watt hours used.

As Don said, not much savings by installing at the load. The exception will be very large loads that run a lot of the time and are a long ways from the metering point. You will also free up some capacity for whatever that might be worth (usually very little after the fact).

I have found some large motors (hundreds of HP) located a long way out into the plant (hundreds of feet) that had a decent payback for capacitors installed at the motor.

 

[PowerQualityDoctor]

I have another opinion

I have another opinion

Yes, if the utility charges penalties, it changes the economic justifications. However, if the PF is less than .7, it makes sense to consider improve the PF near the load (of course, it depends on cable length, cross section and more). Note that 0.7 means that the losses are doubled. Normal losses are between 2-5% (again,depends on many parameter). If yours are doubled, it means you can reduce 1-3% of you bill easily and up to 5% with more spending. It you have one or two large loads - check if you can make local compensation to them. This can be very economical. You are welcome to send the single line diagram at REMOVED LINK, SELF PROMOTION PROHIBITED for detailed analysis, before you spend a dime.