Electrical engineers or whatever help please...

Ahsmo · Post by **Ahsmo** » Wed Oct 17, 2007 11:44 am

Dual voltage motors. I need a skematic for one and the associated motor controller. Am I wrong in stating: "dual voltage motors are used in applications where changing from low power to high power is necessary"

My reference text does not mention anything and I don't trust the internet anymore.

1moreamp · Post by **1moreamp** » Wed Oct 17, 2007 12:23 pm

All three phase motors are dual voltage. They either run on 208 -240 vac three phase or 480 vac three phase The lower voltage is the commercial standard and the the higher is the industrial standard.

Please don't confuse this with Star and Delta wiring as this is two completely different winding configuration used to control motor starting power and overall operating efficiency and current inrush.

Now unless I missed your point those answers should suffice, but considering your in the military your question could mean something totally foreign to me, as the service has their on language about this sort of stuff.

If you need a schematic look up Baldor motors they replace just about everything in the US and can supply just about any frame you might be looking for.
My favorite motor builder is US motors. GM Delco invented the TEFC 7EQ motor specification many years ago, and so when a GM plant does not buy a Delco motor they buy US Motors for use in their factories worldwide.

You should be able to goggle any of that info and get the facts. And since your just looking for the voltage winding connections they should be available from any of those sources, and the National Electrical Code <NEC or the National Fire Prevention Association < NFPA.

Any of those acronyms I listed are the holy grail of the info you want. OR just find a three phase motor and pull off the electrical box cover and underneath you should find the different Hi and Low voltage winding setups, or look at the spec tag on the motor as there is usually a set of wire number connections for the different voltages the motor is capable of.

I would look it up for you but I am behind schedule today and still need to return a call to Jim.....hope this helps if you still need more acronyms just PM me ....C

Ahsmo · Post by **Ahsmo** » Wed Oct 17, 2007 12:41 pm

Actually, I was wrong.

Thanks for the help. This is pretty straight forward. The question is asking about reduced voltage starting. Really the motor is un-important, the motor controller is much more important to the question. I can make up the skematic for reduced starting through an autotransformer.

Thanks! Sorry I wasted your time

1moreamp · Post by **1moreamp** » Wed Oct 17, 2007 1:00 pm

I have not seen auto transformers since the advent of three phase motor controllers and vari-drive controllers, WOW I must be out of step, or the military is still paddling backward

Good luck Ahsmo

Ahsmo · Post by **Ahsmo** » Wed Oct 17, 2007 1:23 pm

1moreamp wrote:

I have not seen auto transformers since the advent of three phase motor controllers and vari-drive controllers, WOW I must be out of step, or the military is still paddling backward Good luck Ahsmo

I am on a merchant ship so technology does not advance very fast. They tend to find something that works and stay with it.

I was on a brand new ship not to long ago and the motor controllers were still basically the same as the old stuff I saw on a steam ship built in the 70s. They had VFD units on the high pressure LNG boil off compressors and soldid state starters on the big 2000kW 6.6kV thruster motors. That was it. The rest of the stuff was pretty much the same old same old.

The military is especially behind. Ask Mastif haha

1moreamp · Post by **1moreamp** » Wed Oct 17, 2007 1:37 pm

Oh I will believe you, My Dad worked for a company rebuilding barge mounted long range radar generators for the military for use in Hawaii, and PR. areas. And I went by time to time to look at all the old stuff they were still using to control power supplies and such for these old monsters of way back. Rheostats, and variable power resistors on a giant scale when everything nowadays is Solid State variable frequency drive. And of course 100 KV rated feed thru's that explode on occasion cause the QC for them was crap.
DI water cooling and SF6 gas for the Microwave waveguides. ( Sulfur Hexafluoride gas ) we use this stuff to etch silicon here is the valley smells really bad and not really safe to breath as it breaks down into sulfuric acid and Hydrofluoric acid compounds that attach calcium in your skeleton and teeth.
Wild shit to say the least. You guys get to enjoy this sort of endangerment daily I would guess, along with getting shot at from time to time, and working on antiques. Wow What a way to make a living. Travel safe my friend....C

Ahsmo · Post by **Ahsmo** » Wed Oct 17, 2007 1:50 pm

The merchant marine world is just as unsafe as the military world in many respects.

I try to forget the things I've come in contact with. I had a little run in with mercury not too long ago... and plenty of carbon cleaner and all the descaler...I'd rather not think about it. I had a little carbon tetracloride get into a cut one time. My boss called me a pussy for wanting to get something to clean it out. haha Cancer is in my future, just a matter of time. Oh yeah Benzine is in everything down in the engine room. Nice stuff.