# MV Power Factor Correction

Hello, everyone. As an EE, I readily understand the theory behind, and the need for, power factor correction capacitor banks on medium-voltge
(MV) AC distribution systems. However, I've always been puzzled as to the method(s) used by the electric utility enginneers to determine the optimum location for installation. I've never come across any handbooks discussing this. Is this done from reactive power (kVAR) estimates from the downstream loads and/or is the power factor measured directly (assuming MV PF meters are available) at candidate locations? Thanks for your time and comment. Sincerely,
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J. B. Wood e-mail: arl snipped-for-privacy@hotmail.com

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On 19/9/2016 3:14 ??, J.B. Wood wrote:

Hi, usually the PFcorrection is being done on a HV to MV substation, and of course on the MV side.I suppose PF can be easily measured with potential and current transformers? I have a couple of slides, too.(Showing those capacitor banks). I saw them on a local substation, 150 to 20 kV, I have also a video from the computers running the cretan grid (Crete, Greece) and they know always the reactive power on each city, also major substation. unfortunately the video is in greek.HTH, HAND, Dimitris Tzortzakakis, ee major.
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On 09/20/2016 09:57 AM, Tzortzakakis Dimitrios wrote:

Hello, and thanks for replying. I think determining the location (pole location, not where the capacitors are fixed on the pole) of capacitor banks on utility poles is more than purely guess work. OTOH measuring anything at MV potentials (~500 volts to 69 kV in the U.S) would be highly dangerous (yes I know linemen work on live wires at MV or higher potentials). So does there exist, say, a mobile van or bucket truck with PF measuring gear that can be parked by utility poles at candidate locations and MV line-line/line-neutral PF measurement be accomplished? The question then is what is the value of PF that indicates the need for capacitor installation at that location? Sincerely,
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J. B. Wood e-mail: arl snipped-for-privacy@hotmail.com

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On 20/9/2016 9:22 ??, J.B. Wood wrote:

https://www.dropbox.com/s/8j8mc41tejb9p3i/DSCI0047.JPG?dl=0 https://www.dropbox.com/s/54xz25teqelheat/PICT0004.JPG?dl=0 On the first photo you can see a high-voltage probe which I bought from germany and can measure 40 kV DV and 28 kV AC. Of course without disconnecting power first. On the 2nd photo you can see an 20 kV circuit breaker, 1500 A and the buried cables that go to the building that houses the rest of the circuit breakers.Just behind you can see capacitor banks, white boxes always line to line because at least in Greece we always have 3 pole MV lines and delta connection for MV. HV has star. So, in Greece the capacitors are placed only on major substations and not on individual poles for MV/LV transformers.I suppose they calculate the "reactive power base load" and proceed accordingly.As for the question how to measure on-site PF I presume they disconnect power first,as it's very dangerous to go near lines that are at MV potential, preferably near a disconnect switch where the cable is already spliced, connect potential and current transformers and then re-energise.I think that a week's measurements would be anough. Then they reverse the process. These are mere speculations by me, of course and I could be woefully wrong.
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I would assume they would be placed in such a way as to minimize the reactive current from the sources to the capacitor banks. For example, if you wish to correct the PF on a segment with 6 equal transformers as reactive sources spaced approximately equally, the capacitor bank would be placed in the middle with 3 transformers on one side and 3 on the other. The reactive current would be half from one side and half from the other.
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On 09/21/2016 10:08 AM, Michael Moroney wrote:

Hello, and perhaps in OP it wasn't clear. What I meant was where along the MV run from the substation do you place capacitors? Sure, once you determine that the PF needs correction at that location then you proceed to select the appropriate kVAR value of capcitors. It's determining the PF at that location that's the issue. Sincerely,
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J. B. Wood e-mail: arl snipped-for-privacy@hotmail.com

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