How to power up the AC drive ?

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technology Associate Join Date: Nov 2008 Posts: 31	How to power up the AC drive ? 03/15/2009 7:19 AM
	Dear SIr We at our factory have around 15 New AC drives in stock since Jan 2006 (.37KW to 2.2KW) with 1 ph. and 3 ph. input supply? All these drives are not powered up at all since 2006, so will it be safe to power up them after 3 years from date of manufacturing?
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JRaef Guru Join Date: Sep 2006 Location: California, USA, where the Godless live next door to God. Posts: 4665 Good Answers: 804	#1 Re: How to power up the AC drive ? 03/15/2009 11:21 AM
	No, you need to do what is called a "reforming procedure" on the capacitors, otherwise there is a high risk that they will short out as soon as you energize them. To reform the capacitors, you need a variable voltage source, such as a variable transformer (Variac, Powerstat, etc.) and a lot of patience. With no load connected to the VFD, you apply a very low voltage to the line terminals (starting from zero) and SLOWLY increase it over time; the rate is 75 volts/minute for 230V, and 150 volts/minute for higher voltages, until you get to the full line voltage rating of the VFD. Then you leave it there for 60 minutes. All the while, you closely monitor the current going into the line terminals from the variac and if current begins to rise, the capacitors are already gone and you need to stop the procedure before you cause collateral damage. By the way, for anyone else reading this with thoughts of STORING a VFD for more than a year, you can avoid having to do this by simply applying power to the line terminals for a few minutes every 6 months. __________________ All I every really wanted to be, was... A LUMBERJACK!.
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CJMcGill Guru Join Date: Jul 2008 Location: SoCal USA Posts: 556 Good Answers: 23	#2 In reply to #1 Re: How to power up the AC drive ? 03/15/2009 7:48 PM
	Well said. I also found more detailed comments at this link, and was by JRaef also. __________________ I do not 'know it all', but i will admit that I would like to. CJM
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anandck Active Contributor Join Date: Apr 2007 Posts: 14	#3 In reply to #1 Re: How to power up the AC drive ? 03/16/2009 2:24 AM
	Dear Mr Raef, Thank you,your answer helped me also. Anand ck
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marcot Guru Join Date: Feb 2008 Location: Montreal, Canada. Posts: 1372 Good Answers: 80	#4 In reply to #1 Re: How to power up the AC drive ? 03/16/2009 9:51 AM
	I agree with most of this except that some AC drives derive their control power from the DC bus. The discharge resistors also draw more current than the capacitors leakage. This means that monitoring the current is (usually) meaningless. If the current spikes from a leaky capacitor, you will not have time to switch off the power. Using a small current limiting fuse (1-2A) in series with your source will make the procedure safer. Also, make sure that the protection covers are installed properly on the capacitor banks in case one of them would explode. If you look at high-voltage capacitor data sheet, most manufacturer recommend reforming after three years without rated voltage applied to the capacitors (it also depends on storage temperature). Powering up every six months as suggested by some of the contributors is excessive. __________________ Experienced is earned, common sense is taught, both are rare essentials of life.
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Anonymous Poster	#5 Re: How to power up the AC drive ? 03/23/2009 11:08 PM
	hi you first clean and dry the windings then megger the windings and if you get a good resistance you charge the drives. Shrikanth
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dadw5boys Guru Join Date: Feb 2006 Location: Piney Flats, Tennessee Posts: 1740 Good Answers: 23	#6 Re: How to power up the AC drive ? 03/26/2009 8:20 AM
	Vaccum out all dust and spider webs __________________ If you never do anything you never have problems.
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anandck (1); Anonymous Poster (1); CJMcGill (1); dadw5boys (1); JRaef (1); marcot (1)

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