over compensation of reactive power

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gova1467 Commentator Join Date: Nov 2008 Location: India Posts: 72	over compensation of reactive power 11/08/2008 8:57 PM
	Dear sir At very low lagging power factor,the real power and reactive power required by the load is supplied by the Tfr.Hence the load draws more current from tfr and therefore more losses,more KVA demand and poor voltage regulation.In this case power flow is from tfr to load. To compensate lagging reactive power due to low lagging PF ,we provide capacitor bank at the load end.therefore we reduce the larger KVA demand,voltage drop,losses ect., by providing correct KVAr of capacitor bank. But if we overcompensate the lagging reactive power,now the reactive power flow is from capacitor bank only.Now in this condition also the tfr is not overloaded i.e KVA demand not increases. Then why the Utility company charges the penalty to consumers if we overcompensate. pl share ur views. regards gova
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#1 "Re: over compensation of reactive power" by Sparkstation on 11/08/2008 10:29 PM (score 2)

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#3 "Re: over compensation of reactive power" by harry potter on 11/11/2008 7:39 AM (score 1)

Sparkstation Guru Join Date: Nov 2007 Location: Christchurch, (The Garden City), South Island, New Zealand Posts: 4395 Good Answers: 230	#1 Re: over compensation of reactive power 11/08/2008 10:29 PM
	Hello gova1467 It is really best not to use txt language here at please - your <"*....Tfr....tfr....pl....ur....*"> as misunderstandings may occur. If you have an over-leading Power Factor (Over-compensated by too much capacitance) in your installation, that leading PF is spread through the load end of the Network. The leading PF may result in nasty Harmonic Resonance, Switching Spikes, Overvoltage, tripping of protection relays, and other undesirable local effects for your installation, the local Supply Network, and your nearby neighbours in the Supply Network. So Utility Company penalizes you to encourage you to correctly compensate so you are not endangering/damaging your own installation, their local network, and nearby consumers on that local network. Please download and read the .pdf document: http://www.osti.gov/bridge/servlets/purl/654078-6lcddX/webviewable/654078.PDF Please Download and read this 8MB .pdf document: http://www.osti.gov/bridge/servlets/purl/654078-6lcddX/webviewable/654078.PDF Apart from that, it is foolish to overcompensate PF, as it results in energy wastage. Kind Regards.... __________________ "The number of inventions increases faster than the need for them at the time" - SparkY
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gova1467 Commentator Join Date: Nov 2008 Location: India Posts: 72	#2 In reply to #1 Re: over compensation of reactive power 11/10/2008 10:38 AM
	Dear sparkstation, Thank u very much sir.I saw ur document attached.I will refer the document and get back to u sir. chears gova
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harry potter

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#3
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Re: over compensation of reactive power

11/11/2008 7:39 AM

Dear Gova,

Effect of Leading pf is equally negative as of low lagging pf.

there are so many factors such as

1. Transmission line losses / Distribution losses are drastically reduced near unity pf

2. Voltage levels are improved near unity pf

3. operating stability is improved on lagging pf. with leading power factor , that is over compensated system leads to inm stability in genearting plants. ( that is why, we switch off extra capacitors while running local dg sets )

4. Over compensated system will lead to more line losses / instability in supploes / etc...

harry potter.

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Anonymous Poster	#4 Re: over compensation of reactive power 12/31/2009 2:09 PM
	Not sure that utility company charges the penalty to consumers when overcompensation. over compensatation helps neutralize other lagging power factor loads. If we can immagine most consumers are overcompensating, which is not practicaly possible, utility company recources would be partialy occopied by reactive current, heated up by losses & has to remove generated heat. Best Regrds Yehya Egypt
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