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ashish patel


{ City } baroda
< Country > india
* Profession * self employer
User No # 37156
Total Questions Posted # 1
Total Answers Posted # 2

Total Answers Posted for My Questions # 9
Total Views for My Questions # 7982

Users Marked my Answers as Correct # 49
Users Marked my Answers as Wrong # 10
Questions / { ashish patel }
Questions Answers Category Views Company eMail

I hv a question regarding power factor improvement just after transformer. I request you to reply me plzz. thank you sir. My friend has a small unit of fabrication. in his factory the main load is a welding machine, lathe machine, grinding machine. this load is not continuous type. now our electricity board has installed 16 KVA, 11000/433 V transformer for our factory. In the energy meter (trivector meter) at LV side of transformer, i hv seen power factor value of 0.15 only when only 3 KW load was flowing. Further electricity board has suggested to install 4 KVAR capacitor at LV side after energy meter. Now my question is that if we permanantly install and switch on 4 KVAR capacitor after energy meter, during some load on transformer and also without any load on transformer, wht will be the power factor shown in energy meter?i dont want to get any penalty by electricity board, so plz suggest me if i can permanantly install and switch on the 4 kvar capacitor or not at LV side of transformer just after energy meter? Thank you again and awaiting for ur positive reply soon.

9 Electrical Engineering 7982






Answers / { ashish patel }

Question { Siemens, 19738 }

how kva rating of transformer is calculated.


Answer

My dear friends,

First of all i want to introduce myself as transformer engr
having 12 years of experience in transformer field. Now in
reply of your question, if u r asking about Name Plate of
transformer, VA = 1.732 * V * Amp
Suppose In Name Plate,
HV Volts mentioned 11000 V, HV rated current mentioned 5.25
Amp, Than Transformer capacity is
1.732 * 11000 * 5.25 = 100023 VA = 100 KVA.

In the same name plate,
LV Volts mentioned 433 V, LV rated current mentioned 133.34
Amp, So Transformer capacity is
1.732 * 433 * 133.34 = 99999 VA = 100 KVA.


If you are asking about to decide transformer capacity, u
hv to calculate your total load + future expansion load.
Than you can take decision about ur required transformer
capacity.

Is This Answer Correct ?    48 Yes 5 No

Question { 8772 }

explain me how a power factor is improved by adding a
capacitor?what capacitor do to improve it?in simple words
and in detail?thx


Answer

My dear friend,

I m describing the answer very simply. If the load is
inductive load i.e. 100 Amp motor load. Then some current
i.e. 75% (75 A) will be drawn by Electricity line & balance
25% (25 A) will be drawn by Capacitors if they are connected
before load. so Electricity billing reduced only for 75 Amp
instead of 100 Amp.

I m using same system for transformer testing. So
technically we can say that we improve PF by using
capacitors, so that we get benifit in Electricity Billing.
If you want further clarification, plz write me on
ashish_patel111@yahoo.com

Is This Answer Correct ?    1 Yes 5 No