350 kVar Capacitor Bank

In the absence of a telephone conversation to determine why it was rejected, try offering 7 x 50kVar on the basis of the unavailability of 35kVar. That way, it could all go on for years...

http://www.google.co.uk/#safe=active&q=35+kVAr+capacitors&spell=1&sa=X&ei=UG3RUf24LYm-0QWvp4H4CQ&ved=0CCgQBSgA&bav=on.2,or.r_qf.&bvm=bv.48572450,d.d2k&fp=63298ca061231fce&biw=1035&bih=548

How about 14 25kVar's?

Would the Client reject it?

Probably not, but we could keep this strung out longer

Your answer is of course fully technically correct . The only reason why I could imagine your customer rejhected it is the multiplication of spares . With 10 identical capacitors, he needs only one spare in case he wants to have one ...

Tell the client that technically the capacitors are added or switched off in steps and for that reason they are normally provided in small denominations. Otherwise proper PF correction cannot be done for the system. Depending up on the minimum requirement 50 kVAR may be connected permentantly and the rest to be added in steps. the 25 kVAR can be switched on and off for fine control. Tell them that your proposal is technically more efficient for smooth and efficient power factor correction. (But the client may require suitable switching system to put the system to operation, actually his system may be designed for 10 step switching hence not accepting your proposal.)

Yes.

And the secondary consideration of the circulating currents passing thru every individual capacitor. Their margins, their heating. Hence their life expectancy. If the customer has any estimates, he is right on insisting of being convinced, with data.

Dear all

10 no 35 Kvar is not wrong ,where ever if the step of contoller is increased it is fine tune with PF relay & it will better maintained.If to take 12 step relay then take 5x50kvar +3x25kvar +2x10kvar +1x5kvar +1step spare better for operation.

There are standard APFC controllers who have specific preset programme depending on your load conditions and variations of PF depending on how much capacitance need to be added automatically and what PF level to be maintained to avoid low PF penality. If the PF is to be controlled properly with the exact desired amount of capacitance to be added is to be chosen by a technical study of the load. So it is not the job of a layman but the job of an experienced designer. So the actual user only can deside what steps are to be programmed and when to add depending on his load conditions. Some loads may be highly inductive ( like Induction Heating )and even though they may have in built PF correction a back up correction at Substation will be needed to maintain proper PF of the system.

From your mail, u said the client needs a Capacitor Bank, Meaning your client only need the bank comprising of 10x35KVar capacitor because they already have the Switching controller which is 10steps and hence if you offer 12 Capacitors thats 12 Steps switching which is not going to work with the available 10 step switching controller because the other 2 Capacitors will be up for waste

Possibly the reason they cant accept your offer.

As per my view 10 step is correct but the subject to avialability of 35 kvar.As 10 & 12 step controller cost is merely same ,it is better to take 12 instead of 10 for fine tune & life of bank.

If 35 KVAR Capacitor is not available as a single unit, your basic lack of engineering knowledge is preventing you from combining two or more units of say 25 + 10 KVAR to achieve the required per unit bank.

The client is only rejecting your lack of technical knowledge but has the decency not to tell to your face.

Its based on client design data not mine,so what,s lack.

Like what i said in my last mail, the client seems to have already the 10 step controller, i advice u suggest any combination that leads to 10 steps and present to your client not 12 Capacitors coz thats will mean the client now suppose to change the controller to accomodate 12 steps.

Hope were Talking the same language Here ...

Try to convince ur client bcos its the the right d/n to adopt.

Does the client design data specifically exclude use of parallel connection of two banks to achieve the required 35 KVAR stage. It is basic engineering. I have personally combined and used various such combinations and had no problem whatsoever.

Maybe some sources can be found by searching for "35 kvar capacitor" on line.

Is it thyristor based switching or contactor based switching. Is any voltage rating specified. Why not follow combination bank as already suggested by other peer.

You could use higher voltage capacitor banks at a lower voltage to achieve your goal.

660V 50Kvar rated banks give you about 35kvars at 480V. They will last for ever!

The problem is that they cost more and are bigger...