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walt1122 01-03-2008 09:55 PM

transformer schematic
Hi I have a second hand powerstat transformer. On their website they show a schematic for a similar model and I have it here as a attachment. Can some one explain how to hook up the line and load?? I'm trying to kick up the voltage a little to use heating wire I wrapped around the plastic pipe on our jet pool bathtub to warm up the water running through it just a little. Right now I'm seeing 98F on the outside of the insulated wrapped pipe. If I can get this up just a little say 115F or so that woud be great. Just trying to keep the water warm a little longer. Figure if I pump up the voltage to 125 or 130 it might help. I think I understand how to run the wire but I don't want to fry circuit if I'm wrong.



J. V. 01-04-2008 01:15 PM

Walt, For some reason I cannot open your attachment. I can't even point at it.
I did find Powerstats web site, but I need a model number. You have a variable voltage transformer (variac). Does it have an adjustment knob or just terminals? You should check your heat tape and see if you can increase the voltage. It will surely make it hotter.
Provide model number for assistance.......John

walt1122 01-04-2008 03:34 PM

Hi John, thanks for getting back. That's funny cause I checed it before I sent it and it looked fine here. I did have some trouble converting it to comply with the size requirements maybe that was it. Anyway the model number that is listed is close and it looks like the one I have. Their model number is 116CU and mine is 116BU so theirs is probably just their newer version. The wire is just something I got hold of from somewhere. Just some resistance wire think it loses .5 watts? or something like that?? per foot. No controls just the resistance in the wire heats it up. The transformer has a big nob and the plate says it can vary the output from 0 - 140V. It looks like their schematic 2 is the closest and as they mention there are no #6 or #7 leads. Looks simple enough but this is not something I want to play around with and screw up.




walt1122 01-04-2008 09:31 PM

does this one show up?? I can see it when I do preview post!

bigredc 01-05-2008 06:58 AM

One is common or white. just tie all the whites and #1 together. Three is the feed in. Then check your voltage at 2 or 4 or 5. It's odd the way they show 2 & 4. But I would just try one at a time not tied together. I'm basing this on the direction of the arrows. If the voltage goes down make 3 the load and 2 or 4 or 5 the feed in. Make sure you hook the ground up to the metal enclosure.

J. V. 01-05-2008 01:38 PM

Walt, I still can't open the attachment. My mouse points at it like text. Don't connect it yet. I am not sure if bigredc is correct. #3 is the wiper and I don't think it is the hot. Not sure.
Call Jenkins Electric in Charlotte NC. Ask for Larry Blackwelder. He knows all about them. Let him tell you how to hook it up. 800-438-3003. These are not cheap. You dont want to short it out. If he asks "who are you with" just tell him I told you to call.

walt1122 01-05-2008 03:24 PM

Hi John, sorry you still can not see the diagram. I think you and bigredc are on the right track. I can see the wires from under the connection block and when I track them I see that the #3 is the sweep as you mentioned. All the others #1, #2, #4, and #5 are all soldered around the outside diameter of the transformer in varying distances from each other. So I'm still confused. thinking that #3 as the sweep and should carry the full voltage in to the transformer then any one of the others should carry voltage out . But the schematic shows two wires One much like bigredc suggests should be the white connected to #1 to carry the neutral But #1 is soldered to the outside of the transformer just like all the others. So I don't get it. Until now based on the schematic and with what bigredc mentioned #1 woukld be white and #3 would be the tap to run the voltage through and pick it up on one of the others. Think I will take you up on your gracious offer, will call Larry Blackwelder and see if he can shed some light on this.

Anyone else have an idea what this is all about??



Stubbie 01-05-2008 04:12 PM

Sorry for some reason I am just now seeing this post. The connections are very straight forward. You will connect your incoming hot (line) to 2 and 4. You will connect your incoming line neutral and load neutral to 1. 3 is your load output and the fuse is probably not supplied so if you want the secondary protected you will need to provide the fuse.

I'm a little surprised that they dont show the arrow on the variac for the rotation direction of the knob. there should be an arrow thru the output load 3 in the up direction if CW or arrow down if CCW.

walt1122 01-05-2008 04:37 PM

Hi John et al, maybe you can see this picture? Not a schematic but a picture from EBAY of some one selling one just like mine with it showing the plate. #1, #3, and #4 are on the copper core side and #'s 2 and 5 are on the shaft side. Plus here is something else I found on the WEB elsewhere talking about transformers. I think it confirms what bigredc was saying although this is really hard to follow??

bigredc, I think this answers the question you had about the schematic relating to #'s 2 and 4...
1) The line voltage is placed across the two endpoint taps: this gives you a maximum output voltage equal to line voltage.

The wiring of most of these is very similar. With luck, along with the terminal numbers, there is a graphic which respresents the coil. Think of this as a single winding with four fixed taps, and one sliding tap. Two of the fixed taps are the endpoints of the winding. The other two taps are placed about 18% from each of the endpoints. The sliding tap is where you pick off your variable voltage. When installing, you have two choices in common practice. (1) The line voltage is placed across the two endpoint taps: this gives you a maximum output voltage equal to line voltage. Generally the line neutral is attached to the endpoint nearest the "0" setting of the dial, and hot is placed on the endpoint nearer the "100/120/140" setting, the output voltage is then picked off between neutral and the sliding tap. (2) The line neutral is connected to the endpoint near "0" as in (1), and line hot is attached to the tap ~%18 away from the endpoint nearest the "100/120/140" setting. This gives the autotransformer a bit of a "tail" above the hot connection, and it is this tail that gives you the ability to get a higher-than-line output voltage. The output voltage is picked off between neutral and the sliding tap, the high endpoint is not explicitely connected in this arrangement: though you will measure ~140V here with a voltmeter. It may also be possible to get even more voltage by connecting line voltage across both of the "inside" taps, and picking output off between the "0" endpoint and the sliding tap, but I have not seen this done. If you cannot determine which terminal is which by inspection or by the legend, you may be able to figure it out with an ohmeter: obviously resistance should be greatest across the endpoints. But because you are dealing with fairly heavy gauge copper wire, you need a sensitive ohmeter: .1 ohm resolution might cut it, but I doubt it: probably .01 ohm or better resolution is needed.

I tried the ohmeter but was not able to interperate the results.

So if I undersand this #1 is white as bigredc said and the hot line (black) will be combined so as to put #'s 2 and 4 together and the output will be the result of where the #3 sweep is on the dial. Still seems funny cause of the way the arrows are on the diagram/schematic



walt1122 01-05-2008 04:43 PM

thanks STUBBIE, think you nailed it. I was getting the same info out on the web as you were answering the last post so I just now saw your message.

thanks again to everyone.


Stubbie 01-05-2008 04:45 PM

1 Attachment(s)
See if this helps

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