Sizing of Capacitor bank

[Kevin Yeo]

Dear all,

Can someone advise how do we size a capacitor bank for power factor regulation. Approx 0.95

Assuming a supermarket with
4 x 18 kW low temp compressor
4 x 30 kW mid temp compressor

10 x 3.75 m double well island freezer
7 x vertical open freezer
15 x 3.75 dairy multideck
8 chiller room
7 freezer room

Main DB is sized at 500 amp to cater for starting high amp.

Wat is the required KVAR and how many steps should I use?

Thanks,
Kevin

[ecclesk]

I think this is quite a specialist subject.

I have recently had new power factor correction equipment installed on my site, (a large cold storage and distribution site). i have a large panel which covers the whole electrical installation on site, the power factor correction is fully automatic and has a controller to bring in & out the capacitor banks (4 in total) as and when required depending on what plant or equipment we are running at the time, we now have a power factor of around 0.98 all the time. I used a company called ABB, it might be worth looking at thier website.

[chemi-cool]

Hi Kevin,

I agree with ecclesk on this one.
You will need an electrical design engineer to design the panel and the controller.

ABB is a fine company but every manufacturer can supply you the equipment.

Make sure that whatever is offered you, replacement parts supply, is not too far.

Chemi:)

[Peter_1]

It's very difficult to predict with the figures you gave.
It depends on the lights in the cabinets used (perhaps already a CAP mounted in it), type of compresser used, is the compresser running in part load or full load, number and type of fans used in the cabinets, fans of the condenser, ...

See for more help http://www.bchydro.com/rx_files/psbusiness/psbusiness1531.pdf

[Kevin Yeo]

Guys,

I've summed up all power consumption for compressors, showcase heaters, lighting and fan to obtain apparent power.

Then to check uncorrected power consumption for each equipment, compressors and so on. Say 0.7

Required KVAR can be obtained [ desired power factor 0.92) by using

Req Kvar = ((tan(inv cos 0.7)-tan(inv cos 0.92))

Till now i have been able to maintain the power factor without problem..

Thanks for the input..

Rgds,
Kevin

[Andy]

Hi Kevin:)

Sorry missed this post. Your are assuming a 0.7 power factor, however it may vary.

The only point I would make is error on the side of caution, make it too big, the controller on the PF Bank will stage it in anyway, using only the banks that are required.

Kind Regards Andy.:)

[Nicolás Vera V.]

Could you let me know what is the nominal power factor in the name plate of the equipment.
So I could help you.
Additionally, You could have two types just one step or automatic two o more steps

[NoNickName]

Be careful of PWS starting compressors with capacitors. They are causing leading currents and stators loss of insulation when starting.

[Dan]

Years ago, Copeland Application Bulletins discussed power factor correction with capacitors and had reservations about it for small compressors, part winding starts (as NoNick mentioned) and certain other applications. It may or may not be relevant, but I will see if I can find it.

Go to https://www.emersonclimatecustomer.com/webapp/wcs/stores/servlet/CTP02_LogIn

Click on "Product information" After you register you can log in and look for online product information. You want application engineering bulletin No. 1249. If that doesn't work, just try starting at an earlier page and get to the Copeland brand and register. http://www.gotoemerson.com/jsp/brands/cli_tech/index.jsp

At least they have some good calculation guidelines in how to do it properly. I could also email you the pdf file if you would prefer.

[ahmed251]

Guys,

I've summed up all power consumption for compressors, showcase heaters, lighting and fan to obtain apparent power.

Then to check uncorrected power consumption for each equipment, compressors and so on. Say 0.7

Required KVAR can be obtained [ desired power factor 0.92) by using

Req Kvar = ((tan(inv cos 0.7)-tan(inv cos 0.92))

Till now i have been able to maintain the power factor without problem..

Thanks for the input..

Rgds,
Kevin
Hello Mr. Kevin
How r u?
We have project and we are using 45KVAR capacitor bank in this project for MCC panel. Now my client is asking for calculation. my total load is 96.3KW.
Actual power factor is 0.8 and targeted PF is 0.95 at 415V, 50HZ. But i am not getting 45KVAR please send me any solution for this.
Request please