# Need Help Understanding This Thing



## oughtsix (Jun 1, 2015)

I just bought a "new "  toy.  The owner had not ran it for 35 years, and I don't know how much older it is. (there were animal bones in the box it came in, so I don't know if I need to hold the bones over it and chant  or not)  Before I plug it in I would like to understand what is going on.  I've attached photos of the phase converter box ( a VFD?) and an attached panel.   The yellow cord is the power supply and that feeds the switch(not shown).

I understand basic wiring, but this is beyond me at the present.  So my questions are:  How does the current move through this thing?  Does it look safe?


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## Firestopper (Jun 1, 2015)

I'm no expert, but I believe what you have is a static phase converter. The three rectangular and single round items are capacitors. I have never had much luck with static converters. I run a rotary phase converter to power the machines in the shop. You can run the machine on a VFD, but that will require more knowledge to set up as well as more money, assuming this is a three phase machine.


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## JimDawson (Jun 1, 2015)

My concern would be the capacitors.  After setting for 35 years they are probably bad.  I would look into installing a VFD, it might be the least cost option.

If you go with a VFD, save the reversing motor starter (on the right), you can use it for something else down the road.


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## brino (Jun 1, 2015)

JimDawson said:


> My concern would be the capacitors.



ditto here.....capacitors tend to "dry out" over the years. If not totally dried out, it _may_ be possible to "reform" them by applying low voltage and slowly raising it higher , but you'd want to take them out of the circuit to do that....

Plugging them directly into high "mains" voltage may find the problems immediately......but it could be dangerous (smokey and explosive!).

It looks like you have a static phase converter like this:
http://www.homemetalshopclub.org/projects/phconv/phconv.html

Also see here for disadvantages of static phase convertors:
http://www.openelectrical.org/wiki/index.php?title=Phase_Converter

-brino


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## RJSakowski (Jun 1, 2015)

The rectangular capacitors are most likely oil filled and should be OK.  The cylindrical capacitor looks like an ac electrolytic.  dc electrolyics can be reformed but I have not heard of that being done to ac electrolytics.  They are two dc electrolytics connected in series with opposing polarities so there is no way to apply a dc forming voltage.


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## John Hasler (Jun 1, 2015)

oughtsix said:


> I just bought a "new "  toy.  The owner had not ran it for 35 years, and I don't know how much older it is. (there were animal bones in the box it came in, so I don't know if I need to hold the bones over it and chant  or not)  Before I plug it in I would like to understand what is going on.  I've attached photos of the phase converter box ( a VFD?) and an attached panel.   The yellow cord is the power supply and that feeds the switch(not shown).
> 
> I understand basic wiring, but this is beyond me at the present.  So my questions are:  How does the current move through this thing?  Does it look safe?
> View attachment 104961
> ...


It's a "static converter".  Looks safe.  In effect, it turns a three-phase motor into a capacitor-start capacitor-run single-phase motor.  I made one for the three-phase 3hp motor on my mill.  Works fine, but it is *not* a no-moving-parts replacement for an RPC and it does not provide variable speed like a VFD does.


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## John Hasler (Jun 1, 2015)

RJSakowski said:


> The rectangular capacitors are most likely oil filled and should be OK.  The cylindrical capacitor looks like an ac electrolytic.  dc electrolyics can be reformed but I have not heard of that being done to ac electrolytics.  They are two dc electrolytics connected in series with opposing polarities so there is no way to apply a dc forming voltage.


I've used decades-old AC caps like that with no problems.  Try it.  If the motor hums but won't start replace the cap and try again.


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## chips&more (Jun 1, 2015)

Somebody needed to convert/trick 1 phase to run a 3 phase motor. If you do not have 3 phase source power, only 1 phase? Then you need one of these or alternatives. If you are not on a budget, then I would go with a VFD. If you are on a budget, then keep what you have, and try it out. Hook it up and test it. Make sure your power source is breaker/fuse protected. You will probably find out in the first second or two if the thing is going to work. I can’t see any damage being done to the motor in that kinda time if the cap(s) are bad. Maybe a growl from the motor or a puff of smoke from a cap(s). Just be prepared. Stay out the way and have a fire extinguisher handy. Not trying to freak you out, but just want to see you be safe. You might be surprised and find out it works. You can always check the caps with a meter before you proceed. Take them out of circuit first. Good Luck, Dave.


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## oughtsix (Jun 1, 2015)

Thanks for all the replies.  It is a 1 HP 3 phase motor running off 240v .   It will be a few days before i power it up ( I'll get the right fire extinguisher, too) .    May even have to video the startup if it might explode!..

-06


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## coolidge (Jun 1, 2015)

Caps can explode and make a mess and stink.


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## oughtsix (Jun 2, 2015)

I took all the caps out and checked them,  the run caps were still good, but the other one wasn't up to spec.   For about $30 I am replacing them all.  The run caps were made by GE  a loooong time ago.  Decided that  replacing them was better than having  a hazmat site if they  blew up and spewed whatever was in them.   Looked into  the VFD,  only  $100 cheaper than  replacing the motor with a single phase 220v.    that may be an option down the road.


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## mksj (Jun 3, 2015)

Would be curious to know what your new toy is?  Good idea to replace all the capacitors, the paper and oil caps can last a long time (but they do go), the electrolytics just dry up and die. Good idea to replace all of them for a nominal price, and use higher AC voltage rated caps. You may consider replacing some of the older wires and terminate all the wires with ring terminals while you are in there. Looks like an hybrid of old and new. I would suggest running an additional ground wire between the contactor box and phase converter box, although the metallic conduit is used, the connections can get crusty and poor with time. Current code no longer permits conduit to be used as a ground. When dealing with electricity at these voltages, I get a little paranoid. I have amplifiers running 1000+volts, not a lot of second chances if something goes wrong. 

The VFDs can be had for not much more if needed, but will be interested in hearing how everything works out. Always a learning exercise.


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## 78MVN (Jun 3, 2015)

Hi there.  I have been lurking for a bit but this is my first post.  I too am wondering what the new machine you have is.  The reason being is that a VFD might be a better choice than changing to a single phase motor.  This would depend on what the machine is and if having variable speed would be beneficial.  Just a thought.

Nice forum all!  Glad to have found it.


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## oughtsix (Jun 3, 2015)

My new toy is a barrel rifling machine.  It pulls a rifling button thru a bored barrel  along a spiral track.  This presses, rather than cuts the grooves in the barrel.  At least that is what  they told me.  Can't wait to see how it works.  Picking up the new parts this after noon.  

Will post photos of the thing when it is all put together.


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## larryr (Jun 3, 2015)

you have a static phase converter. they work fairly well, although they wont start a heavy load and only produce about 3/4 of the rated motor hp. if this setup ran for 30yrs i would start it up and see if it runs. if the converter or motor has problems i would look for a replacement 1ph motor. just make sure its reversable. a vfd is another option and you can probably source one on ebay for about $130. this will give variable speed. for and rev , controled braking and other options you might find usefull. i would not sink any money into that static phase converter ,they are at best a half assed solution to running a 3 ph motor. they internet is full of all kinds of info on these converters if you decide to go with it.


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## oughtsix (Jun 4, 2015)

Replaced the 4 capacitors,  plugged it in and BWWAaaaahahaha, It's Alive!.      No strange sounds or smells, that's a bonus.  May still get a vfd  or single phase motor in the future, but this runs.

may be a while before I produce any thing, but got the first step done


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## mksj (Jun 4, 2015)

Sweet!  

A single phase motor is more likely to cog, which may affect the smoothness of the boring (pulling) process. Many individuals have noted significant improvement in their lathe finish when switching from single phase to 3 phase (and addition of a VFD). The additional benefit for the VFD would be the ability to change speed, and also maintain a fixed speed through the pull. Can't say if it would be better, but it certainly would not be detrimental.


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## John Hasler (Jun 4, 2015)

mksj said:


> Sweet!
> 
> A single phase motor is more likely to cog, which may affect the smoothness of the boring (pulling) process. Many individuals have noted significant improvement in their lathe finish when switching from single phase to 3 phase (and addition of a VFD). The additional benefit for the VFD would be the ability to change speed, and also maintain a fixed speed through the pull. Can't say if it would be better, but it certainly would not be detrimental.


A three-phase motor on a static converter won't run nearly as smoothly as it would on three-phase power.


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