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Addition of pf correction - useful to whom?


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#1 saidaibala

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Posted 15 July 2006 - 11:11 AM

Hello marke,
in one of the posts, u had said that addition of power factor correction equipement is of no use
to the user,since the KWh meter readings are based on actual KW consumed.

Then it should be of some use to the power supply compnay since they insist on PF correction?

Of wat use, is it to them?

Regards,
bala

#2 jraef

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Posted 15 July 2006 - 07:39 PM

It allows them to sell more power from the same transmission equipment. They cannot sell reactive power, only useful power, but their system must supply the reactive power, so that represents operating losses because it does not bring in revenue. By requiring the customers to supply their own reactive power, the utility can connect to more working (billable) loads with the same equipment.

Correcting the pf then can have a benefit for the user, IF the utility charges them a penalty or surcharge for poor power factor.
"He's not dead, he's just pinin' for the fjords!"

#3 marke

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Posted 15 July 2006 - 08:27 PM

Hello saidaibala

The addition of power factor dorrection will not reduce the KWs consumed by the load. I will reduce the reactive current upstream of the capacitors and will therefore reduce the line and transformer losses supplying the circuit up to the power factor correction.

The major advantage is to the power company supplying the power, but if there are significant line losses within the plant on the supply side of where the capacitors are connected, there can also be some KW reduction as well. If there is significant KW reductionwithin the plant, the cable used must be well undersized.

In some circumstances, the cable from the supply to an individual motor may be too small, resulting in significant voltage drop to that motor. This will icreases the line losses to that motor and reduce the voltage supplied to that motor. The addition of static correction may reduce the voltage drop at the motor terminals. This will reduce the current drawn by that motor.

Where a customer has their own transformers, the addition of power factor correction can increase the maximum load that can be connected to a transformer. Transformers are loaded by KVA, not KW.

Best regards,

#4 brod

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Posted 16 July 2006 - 07:00 AM

I have observed that capacitor banks (MVAR) along the line are used to increase line voltage (KV), this is to reduce the current going to the customers. I think it is beneficial to the customers since consumptions are based on MW and the MWmeter are dictated by the current (Amps). Am I correct?
Pls explain... thnx U

#5 marke

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Posted 16 July 2006 - 08:06 AM

Hello Brod

The MW meter is sensitive to the current times the voltage times the power factor. If you improve the power factor, the current will drop but the power will stay constant.

For example, if you have a power factor of 0.5 and then correct it to 1.0, you will halve the current, halve the MVA, but the power will be the same. The meter will record the same power consumption.

Best regards,

#6 brod

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Posted 16 July 2006 - 01:17 PM

Thnx Mark,

I have observed that when I online say, 7.5Mvar Capacitor Bank some 70kms from my station (along the transmission line), it has a corresponding increase of around 2Mw on my Mw meter, also a 2kV voltage improvement. This is a 69kV transmission line.

thnx u....

#7 kens

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Posted 16 July 2006 - 10:28 PM

Hi saidaibala, improving the power factor is certainly of assistance to the network company as theyneed to have transmission componants sized to suit the kVA carried rather than kW. The effect of poor p.f. can cause overloading throughout any transmission system. The result of this is that generally there will be some form of charges from the supplier that are affected by power factor. These can take the form of a direct reactive power charge or it could be that you are charged by kVA for the network component of the power bill. Here in New Zealand we are currently facing some fairly severe transmission constraints. We now see most of the netrwork companies charging either a direct reactive charge or including a kVA charge. These can be very significant and will go a long way to payng for correction equipment.
It really comes down to the way that you are charged for your supply. Having a high p.f. will not make your equipment operate any better (besides a reduction in losses) but it could be costing significant money.

Cheers
Ken
An expert is one who knows more and more about less and less until he knows absolutely everything about nothing

#8 mannu

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Posted 19 July 2006 - 12:34 PM

QUOTE(saidaibala @ Jul 15 2006, 11:11 AM) View Post

Hello marke,
in one of the posts, u had said that addition of power factor correction equipement is of no use
to the user,since the KWh meter readings are based on actual KW consumed.

Then it should be of some use to the power supply compnay since they insist on PF correction?

Of wat use, is it to them?

Regards,
bala



hi everybody,
i m new to this forum
you all can get knowledge about the power factor improvement just palying with the power vector diagram..
for supplier: supplier wants to supply more n more active power at good pf..n it can get by just reducing the reactive power n increasing the active power while keeping the constant apperant power.so supplier can supply more active power at good pf and can get good revenue...but reactive power is always there so power factor at supply end cant be unity.

for end user: if supplier poses penalty on consumer for poor pf..then consumer can use capacitor bank to improve power factor...again u can play with power vector diagram..keep active power constant n decreases the reactive power...n in that case you can improve the power factor up to unity...i think so
....
thanx n regard

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