# Portable device to power up a VFD



## JRockey (Apr 9, 2018)

Ok so this is probably an oddball request but it would really come in handy for my business. Often times I purchase drives from plants that are shutdown and no power service. I have to make a guess on runtime hours and megawatt hours based on visual clues which can be deceiving. So all I would need is a power supply that can single phase (AC) the drive enough to get the bus voltage up and check parameters for hours. Possibly even a DC source that I can right into the dc bus. Im hoping there is something out there, otherwise we will have to make something.


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## Peewee0413 (Oct 18, 2012)

Get a small transformer, wire it up 120 in 480 out.

Sent from my SM-G965U using Tapatalk


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## LARMGUY (Aug 22, 2010)

You could add a bridge rectifier for the DC. Depending upon the situation I'd also put it on a roll around cart.


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## JRockey (Apr 9, 2018)

I am hoping for a hand carry device that I can carry through a plant. So obviously I will need some good batteries to start with. Hoping this unicorn already exists.


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## Wardenclyffe (Jan 11, 2019)

https://scanhi.com.au/equipments/honda-generators/honda-inverter-generators/eu10i/


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## MikeFL (Apr 16, 2016)

Portable battery booster and an inverter.


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## JRaef (Mar 23, 2009)

Peewee0413 said:


> Get a small transformer, wire it up 120 in 480 out.
> 
> Sent from my SM-G965U using Tapatalk


 That's exactly what I have for this purpose. I got a NEMA 1 vented enclosure, put a 100VA Control Power Transformer inside and wired a 120V plug and toggle switch to the LV side, then wired the HV side to fuses and a selector switch that gives me 240 or 480V on the output cord, with pins on the end for wiring into VFD input terminals. I also put a drawer handle on top to make it easy to carry around. I have yet to find a VFD that needed more than what that 100VA transformer could supply just to power up the electronics.


I wanted to post a pic of it but I realized that I loaned it out to someone last year and I cannot F-ing remember who it was now. Dammit!


Here's the box I used though.


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## micromind (Aug 11, 2007)

JRaef said:


> That's exactly what I have for this purpose. I got a NEMA 1 vented enclosure, put a 100VA Control Power Transformer inside and wired a 120V plug and toggle switch to the LV side, then wired the HV side to fuses and a selector switch that gives me 240 or 480V on the output cord, with pins on the end for wiring into VFD input terminals. I also put a drawer handle on top to make it easy to carry around. I have yet to find a VFD that needed more than what that 100VA transformer could supply just to power up the electronics.
> 
> 
> I wanted to post a pic of it but I realized that I loaned it out to someone last year and I cannot F-ing remember who it was now. Dammit!
> ...


Using a variac on the 120 side would work for reforming capacitors too.


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## JRaef (Mar 23, 2009)

micromind said:


> Using a variac on the 120 side would work for reforming capacitors too.


I know. I keep my eyes open for a cheap variac on Craigslist or Fleabay all the time. Unfortunately people have discovered them as a way to vary the sounds their electric guitars make (Eddie Van Halen's "brown sound"), so the cheap ones get gobbled up.
:vs_mad:


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## gpop (May 14, 2018)

micromind said:


> Using a variac on the 120 side would work for reforming capacitors too.


Im going to have to try that.


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## dronai (Apr 11, 2011)

gpop said:


> Im going to have to try that.


Me too, that's a handy tool for bench testing


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## micromind (Aug 11, 2007)

gpop said:


> Im going to have to try that.


I've done it maybe a dozen times over the years. 

I don't know if the caps would blow if powered with 480 or not, I'd rather not take the chance.......


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## MotoGP1199 (Aug 11, 2014)

Here's a box I made a few years ago. Sounds similar to what JRaef has. I backfed a 250va step down transformer I removed from an old control cabinet. All the parts were stuff I had in the van or shop except the voltage display. The handles on top were leftover from our kitchen cabinets. They protect the switch in the van and used to carry it(kind of heavy). I have used it on many drives for programming at the shop or testing displays etc with the load removed from the drive.

Note: you will see the secondary fuses are not directly after the transformer. I put them after the HOA switch so I would protect both wires going out of the box on either voltage. Also there to protect if the cheap CE stamped voltage display fails. I'm assuming the CE stands for China Export and not CE approved, lol.


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## paulengr (Oct 8, 2017)

MotoGP1199 said:


> Also there to protect if the cheap CE stamped voltage display fails. I'm assuming the CE stands for China Export and not CE approved, lol.
> 
> 
> 
> > What’s the difference? CE can mean it’s actually third party NRTL tested, or made of “similar materials” and self tested. So it might as well be made in China. CE is not a recognized mark in the US. Neither is....wait for it, MSHA. That’s right folks the government run lab that is part of a division of OSHA is NOT recognized by OSHA! Now of course if it was an upload of a research paper from a Chinese Communist Party propaganda group to the CDC, they’d trumpet if as science.


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## SteveBayshore (Apr 7, 2013)

I don't think MSHA has any connection to OSHA. MSHA is not a "lab"; it's a worker safety training and enforcement agency.Two totally separate government agencies. I received my original MSHA training in their headquarters in Beckley, West Virginia in 1999. They are both part of the US Department of Labor and operate independently and are funded differently; at least as explained by the MSHA trainers and inspectors we have encountered. Surface mines must be inspected twice yearly, with no exceptions and no advance notice. Will also inspect with an accident or complaint. Nothing on the MSHA site that we deal with ever mentions OSHA. Do you know of a connection that I don't?


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## paulengr (Oct 8, 2017)

SteveBayshore said:


> I don't think MSHA has any connection to OSHA. MSHA is not a "lab"; it's a worker safety training and enforcement agency.Two totally separate government agencies. I received my original MSHA training in their headquarters in Beckley, West Virginia in 1999. They are both part of the US Department of Labor and operate independently and are funded differently; at least as explained by the MSHA trainers and inspectors we have encountered. Surface mines must be inspected twice yearly, with no exceptions and no advance notice. Will also inspect with an accident or complaint. Nothing on the MSHA site that we deal with ever mentions OSHA. Do you know of a connection that I don't?


Ok first you got part 48 so you only saw part of it. At various times I’ve done underground, surface, coal, metal/nonmetal, and quarries. Surface is 2+. Underground and coal is 4+. And new miner training goes from 24 to 40 hours with tougher restrictions on who can be a trainer. And you have to be an MSHA certified electrician for coal. And here’s the twist, equipment used underground and in coal mines must be MSHA approved. At one tine it all had to be third party tested at the MSHA lab. In recent years (the last 5-10) they are slowly accepting UL and other standards and NRTL testing other than their own. But for the most part everything electrical in particular underground or in coal must be MSHA approved. That’s why for instance it took decades for cap lamps to switch to LED and why there are special mining approved cables, switchgear, breakers, you name it. Even conveyor belting has to be MSHA approved.

Historically Interior had MESA which was moved into Labor and renamed MSHA in the 1970s. All their research used to be done by the USBM, also Interior, but that was scrapped by Clinton in 1996 to balance the budget. Unlike OSHA in some ways their regulations make sense. The entire electrical section fits on two pages, 12 point, single spaced, one side only. It contains things like you need protection against short circuits. It doesn’t say how to do it. That’s an advantage over NEC but the problem is that it also means MSHA can interpret or re-interpret it to read however they feel like it. Think of a local Code inspector except that they are complete idiots and free to just make things up. The back log for suing them is 6.5 years currently. There is one industry wide case over extension cords that has been in court for over 20 years.


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## JRaef (Mar 23, 2009)

MotoGP1199 said:


> Here's a box I made a few years ago. Sounds similar to what JRaef has. I backfed a 250va step down transformer I removed from an old control cabinet. All the parts were stuff I had in the van or shop except the voltage display. The handles on top were leftover from our kitchen cabinets. They protect the switch in the van and used to carry it(kind of heavy). I have used it on many drives for programming at the shop or testing displays etc with the load removed from the drive.
> 
> Note: you will see the secondary fuses are not directly after the transformer. I put them after the HOA switch so I would protect both wires going out of the box on either voltage. Also there to protect if the cheap CE stamped voltage display fails. I'm assuming the CE stands for China Export and not CE approved, lol.
> 
> ...


Very nice, and yes, almost exactly what I had made (I didn't have the display though). I'd be slightly concerned about the heat in that unvented box though, but it depends on how long you plan on using it. Still, nicely done.


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## MotoGP1199 (Aug 11, 2014)

JRaef said:


> Very nice, and yes, almost exactly what I had made (I didn't have the display though). I'd be slightly concerned about the heat in that unvented box though, but it depends on how long you plan on using it. Still, nicely done.


Thanks, its not vented well, but it is vented. There are four 1/2" holes in the back that are intended for mounting brackets (you can kind of see two in one of the pictures near the top corners) and two 1/4" holes in the front under the lip(can't see in the picture) so you can switch the hinges. I left all of those unplugged. I have run the unit for over 4 hours and the enclosure doesn't even get warm to touch at all and the transformer gets slightly warm. I had thought about that in the beginning and figured I could add some holes/vents if I needed to, but after monitoring it my laptop gets hotter than the enclosure or transformer to touch, lol.


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