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Electric Motors/voltage selector switch

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Question
I have an older compressor with GE motor 5KCR49TN2235X. 120/240v. I would like to install a voltage selector switch but cannot find one. It's probably just a dpdt switch but the ones on newer models have a label saying 120 & 240. Do you have a link to purchase one of these switches?  Thanks

Answer
Chuck    yes we can find one,   but why would you swap voltages to a compressor?

I understand that is not your question, but you have my curiosity working,   

Can you tell me a little more about your setup?

Feel free to use my personal email it is a bit faster    

I am envisioning 240 volts coming to a compressor,   but before it gets to the compressor it has a voltage selector   which would simply take one hot and neutral and feed the compressor,    

But are you wanting a switch to change the COMPRESSOR MOTOR CONFIGURATION or are you wanting to change 240 to 120 and back and forth      and if so why?

I am often amazed at the ideas people come up with    so I am asking in a positive way    

Are you on to something most of us went blowing right by?

I am assuming   and you know that is a bad thing to do,      that you want to make the MOTOR useable on 120 or 240   like a portable compressor      so if the site has whatever voltage   you just swap your switch versus chasing all over for the voltage that matches your compressor,       


DPDT switches normally with center off  are for reversing,    

If you are going to do what I think you want to do,   you are going to parallel the windings for low  and then put them in series for high  

A compressor motor is normally either a capacitor start or a capacitor start capacitor run motor,   it could have 6 to 10 leads out,   or terminals    that have to be paralleled than put in series,       so a STANDARD two pole double throw MIGHT do it,  but then again if it is any HP at all  you are talking one big ass switch

The problem is the serial or model number with a vintage GE motor is not going to give us any DETAILED information,   MOST LIKELY and I just hit what database is left of GE motors and that 5KCR49TN2235X  does show as a 5 HP regular duty motor or a 4HP special compressor duty,  [they do that because compressors in that size range don't have unloaders and can be put in a start situation where the compressor motor overcomes locked rotor but is faced with fighting back pressure  so they call it a 4HP with a 1.25 service factor    instead of a five HP motor    

So do we have 6 leads [four runs and one start] 7 leads a P lead or maybe a P1 and P2 ?  or eight leads  [four runs and two starts, with two thermal leads]

IS the voltage change connection diagram still with the motor   on the nameplate or maybe in the cover of the connection box?

Most single phase motors change voltages like this      120/240     The start Circuit including winding is 120 volts  PERIOD       the run is 4 leads    that allows for the poles to be in series   or parallel      low  1-2 to line,  3-4 to line   then add 5 to either pair  for a start lead   and eight to either pair for a start lead,      then high voltage series  is  1 to line    2 and 3 and ONE START  electrically connected and isolated      4 to line with another start


this is labeled weg but it is NEMA so standard  any single phase connections look like yours?

http://catalog.wegelectric.com/img/Wiring_Diagrams.pdf

So the 120 volt start winding is always at 120   when it is connected for 120 it is obvious,  when it is connected for 240   that series connection  of 2 and 3  adding in a start  puts the start winding half way in the run  and at that point it is only 120 volts to the start  while the motor itself is 240     

So you see the issues to deal with,  but contractors do this all the time,     

Another way they do it is a transformer,   but something else to pack around,   but real simple as far as no switches of the motor windings back and forth      

You wont find a switch labeled  electric motor voltage switch   or anything like that,  it is going to be some sort of MAYBE a double throw switch   again depending on the HP and amps, or a drum switch,      

Another way to do this    if you want a first class compressor motor,  is to use three phase  and use a variable frequency drive to swap the incoming from 120 or 240  but the advantages are you have a way less costly motor    a more durable three phase motor,  and you have built over current protection,  a nema one enclosure   and   by the time you buy an expensive single phase motor     and a switch       you can almost if not buy a three phase motor with a drive  which is a hell of an improvement over a  single phase motor with caps and internal switches and all that,        

Something to think about,

The next link gives you how to change the motor leads for voltages that is a start anyway  

http://www.doityourself.com/forum/electrical-power-machinery-tools-sharpening/49

http://search.assist.shaw.ca/shaw.search.keyword/search/video?q=Dual%20Voltage%2

Here are some links that may help   

If that is a Craftsman   the model on the compressor MIGHT lead you to a Craftsman PART Number for a voltage change switch  but that is a compressor part not a motor part

long one with several helpful ideas     

http://books.google.com/books?id=Yxy8WRWfIy0C&pg=PA72&lpg=PA72&dq=dual+voltage+s

Bottom line  there is no voltage change switch that is generic   I know what I think you are looking for if I guessed wrong let me know,  remember if this is the motor that shows up by that model  it is 5 HP worth of current  so the switch has to handle that current at low voltage    I doubt there will be a regular dpdt switch     you will most likely need a drum switch to handle the current,  

Again if you use this a lot on job sites  I would consider a 120/240 single phase in three phase out VFD in a NEMA one enclosure       that solves a lot of headaches   let me know how you get along  

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Three phase/ AC DC single phase motors, controls, any problems or failures, motor installation, performance issues, connections. All other electric motors/gearboxes/apparatus. Specialty repair concerns, obsolete motors and solutions. Other mechanical or specialty equipment. See my profile under Home/electrical at this site

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