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Customer Question

The theory of two hot connections has always been a little confusing for me. I am trying to get a 115v little pump to run off of 230v.

I have a 240vac connection on a piece of medical equipment. There is a little pump on there that runs on 220v @.11amps. The pump that I am talking about is no longer supported at 220vac they only make it in 115v now.

I bought this transformer http://www.alliedelec.com/search/pro...x?SKU=70009008 and I can not get it to work. I hooked black and red to the two pin connector which is 240vac. And I hooked Black and white to my meter and BOOM tripped the breaker. Will this transformer work? The connector is 120v on each side relative to ground (the machine Chassis) it is a 2 pin connector. The pump is just a little 115v pump with two wires.


PLEASE help!

Submitted: 371 days and 18 hours ago.
Category: Engineering
Value: $30
Status: CLOSED
Expert:  ibosley replied 371 days and 17 hours ago.


ibosley :

Hello, I know a thing or two about wiring, maybe I can help. The link you have posted is broken, I can't see what transformer you ordered.

Typically a 220V will have a red, black, white, and bare wire. Is that what you have? Also, when you hook it to your meter what kind of meter is it and what setting is it on? Also, what is the amperage of your breaker?

It sounds like you are testing it wrong. As long as you do not ground it out by hooking it to the meter it shouldn't flip the breaker. I suggest going to the breaker and verifying that it is hooked up properly. If it is you will have a red and black that are the hot wires, with a white wire as neutral. The red and black wires are both 60 hz and 110v and are 180 degrees out of phase. This means only one of them is hot at any given time. But when I say time I mean 1/60th of a second each.

To create a 110v outlet you simply take the black and white wires and hook them to your pump motor. There is no need to transform the signal or voltage. Let me know what you discover.

Customer :

No, all I have is a 2 pin molex connector with 220vac. 120v on each pin relative to ground. The pump can not be simply plugged into the wall it must come from this connector. The transformer (link below) is a auto-transformer which is different from a standard transformer because it has no isolation. It shares one priXXXX XXne with the input. It was chosen due to cost and size concerns. The meter was a Fluke 179 and this is not an easy answer, I have a electrical engineering degree from UMD and I work for Siemens AG as an electrical engineer. I was a technician in the Navy for 10 years before that. This is a circuit in a half million dollar machine that I am working on retrofitting for our field technicians. I am just away from work and needed a second opinion without sounding dumb to my co-workers. Experience with autotransformers with 3 wires is kinda needed to answer my question. I hope you can help.

http://www.alliedelec.com/search/productdetail.aspx?SKU=70009008

ibosley :

I guess I still don't understand why you just can't take 1 pin of the molex connector and hook it to the chassis grounded motor. I'm just a mechanical engineer though. You also have a lot more experience than I. I'll opt out to let someone else have a crack at it. Good luck!

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Expert:  Josie-Mod replied 370 days and 23 hours ago.

Hi, I'm a Moderator for this topic and I wonder whether you're still waiting for an answer. If you are, please let me know and I will do my best to find another Professional to assist you right away. If not, feel free to let me know and I will cancel this question for you. Thank you!

Customer replied 369 days and 18 hours ago.

Please cancel the question. It was tough not his fault.

 
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