Please please help with a switch issue hooking up my 3 phase

Discussion in 'ELECTRICAL ISSUES - POWER YOUR MACHINES & SHOP' started by cincinnati JA, May 23, 2013.

  1. cincinnati JA

    cincinnati JA Active Members Active Member

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    Ok I have the 5hp rotary phase converter which is a 3 phase motor which is run of 2 legs single phase and the third leg is generated by the motor . Now the issue is I have a master electrician friend who bought me a fusible disconnect that is called a pull type . It is a good enclosure but I cannot use it as an on off switch or let's say I don't feel comfortable using it as a on off switch. So I went to a huge electrical supply store and talked with a card carrying electrician about a on off switch or start stop switch and I wanted it inline with the power going to the phase converter but he kept telling me that it wouldn't work that way. And blah blah he brought out this switch which looked exactly like what I wanted and I bought it and was happy but I pulled it apart and it is a momentary switch which I am assuming I must use a relay with . Which is fine but I have no idea how a momentary switch works with AC power .

    I think I understand that the momentary switch energizes the relay and starts the machine , maybe? But I'm still confused . Here are photos can someone please explain this to me . What I want, whether is be a momentary button or breaks type start stop, I want to be able to push start and stop to turn the machine on or off.

    [​IMG]
    This is the inside of the phase converter I have close ups if anyone needs them .

    [​IMG]
    These are the two switches the one on the left is a breaker type start and stop and the one on the right a momentary push to start .

    [​IMG]
    [​IMG]
    This is the inside of the breaker type switch this is for a three phase but can be used as a single phase as well. But I want to keep it on the shaper head with my Cincinnati mill. Obviously this type switch works with the power online to the motor... I don't know why that electrician was telling me switches can work this way.

    [​IMG]
    [​IMG]
    [​IMG]
    This is the inside of the momentary which I'm not exactly sure how this works so if someone could explain that would be awesome! But again I think I need a relay with this one .

    [​IMG]
    This is the inside cover I've the disconnect


    Basically I have a fusible disconnect and I want a start stop switch in between that and the phase converter . Or should I just take out this disconnect and put a knife type disconnect and just use that as my on off to the converter ? No the converter did not come with its own on odd switch. When you apply power to it . It comes on .

    Please please help!
     
  2. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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  3. cincinnati JA

    cincinnati JA Active Members Active Member

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    Tony , first off thank you very much for that. I don't know much about electronics so even that article confuses me . I mean I can basically understand it but all of the schematics are for 3 phase momentary buttons . I need single phase 240v hook up going into a phase converter that generates a third leg "T3" I just read a thread on here and I am guessing I need a starter or a relay of some sort ? Maybe I should just get the knife type disconnect and move on!
     
  4. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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    Are you wanting control of the generated 3 phase with the start/stop station, or control of the phase converter?
     
  5. Ulma Doctor

    Ulma Doctor Moderator Staff Member Supporter

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    if you were so inclined you could use the start/stop to operate a contactor or motor starter.
    that would effectively disconnect the main power when open.
    your on/off switch doesn't appear to have the capacity to switch large inrushes of current or voltage.
    the contactor or motor starter does have the capacity for large voltage/amperage inrush if sufficiently rated, to switch all power legs simultaneously.
    the on off switches would only switch control current to energize the contactor coil.
     
  6. cincinnati JA

    cincinnati JA Active Members Active Member

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    I want to control the phase converter motor itself on or off. It will be a switch between the disconnect and the phase converter . After the converter it goes to a 3 phase panel and then from there my mill and my grinder will be hooked up and they have their own switches. In your opinion is a knife type disconnect ok to use as a on off switch on a regular basis or is it not ideal? I think I need to sit down and read the link you have me again and do some more educating of myself . It's a lot to take in . I wonder how much it would cost to buy a starter and a relay or if I can get away with just a relay ... Or from the photo of the converter can you see where a starter or relay would be to start the motor? Or 3rd option , just by a non fused knife switch to cut it on and tie it into the fused disconnect .

    - - - Updated - - -

    So I understand the breaker type switch not being able to carry the load but why? Because it cant withstand the consistant load And does the momentary allow it to carry the load because it is momentary ? So all I need is a motor contractor or starter in between the the switch and the wires to the lugs on the converter ? How would I choose what contractor or starter?
    Also the breaker type was hooked up to the 3 phase shaper motor which was hooked up after the starter so is that why that switch can work as a on off on the motor?
     
  7. cincinnati JA

    cincinnati JA Active Members Active Member

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  8. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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    Since your phase converter is powered by single phase, you only need a 2 pole switch, or contactor.....whichever you choose. It is not necessary to have a contactor if you have a heavy enough switch, BUT, it would be more convenient to use one. In that case, you would set up your push button station to energize the coil on the 2 pole contactor (relay with heater). You will need to either use a contactor with an adjustable heater, or a properly sized fixed heater.

    Can you give us the make and model of the phase converter? I'd like to see the schematic for it before I give further advice.
     
  9. Ulma Doctor

    Ulma Doctor Moderator Staff Member Supporter

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    So I understand the breaker type switch not being able to carry the load but why? Because it cant withstand the consistant load And does the momentary allow it to carry the load because it is momentary ? So all I need is a motor contractor or starter in between the the switch and the wires to the lugs on the converter ? How would I choose what contractor or starter?
    Also the breaker type was hooked up to the 3 phase shaper motor which was hooked up after the starter so is that why that switch can work as a on off on the motor?[/QUOTE]

    the breaker switch may not have sufficient capacity to carry the full motor load, you can still gain it's use you would just have to design the circuit differently than the momentary. just remember switching control circuits can be done with light duty switches, there is usually less than a couple amps involved.
    when switching motor loads there is potential to switch larger amounts of current, therefore the need for more robust parts.

    yes, a contactor or motor starter of your choice can be installed to provide electrical control.

    Starters can be rated in Horsepower or Amps drawn. i would suggest for economy to use definite purpose contactors whenever possible. they are widely used in the Air Conditioning,Refrigeration,and industrial applications way to numerous to list.
    they are sturdy, cheap and available easily.
    i always over rate my contactors, if the circuit calls for a 15 amp, i install a 20 or 25 amp and they last for a long service life.
    EBAY is packed with them.

    that's correct, the breaker shut off all three phases at the same time. but there is no rule stating that you must use all three lugs at the same time. a single phase motor will pull a lot of current to start, even more current will be drawn by a 3 phase motor trying to start on single phase. once the pony motor is running current levels are dramatically reduced.
    start up is the hardest part, once the pony is running the single phase we introduced to the motor is auto generating the third leg through induction, giving the 3rd phase
     
  10. itsme_Bernie

    itsme_Bernie Active Members Supporter Active Member

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  11. cincinnati JA

    cincinnati JA Active Members Active Member

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    Tony the make and model is here .

    http://www.dempseyandco.com/phase_converters.htm

    It's a local company and he did not give me a full schematic of the internals so tomorrow I am going to see him about it. I didn't realise motor starters cost so much money!

    Anyways I did a little research on the parts inside the converter and I'm learning a lot doing so. The item in the top left corner is a motor starter it is a Allen Bradley bulletin 709 size 1 , 3 phase starter . So it looks like I already have relays and a starter . The key is now if I can use this switch with it . That's why I want to go see the guy who built it. He is kinda of a simple guy so he may give me crap about wanting to use the extra push button station. I hope not because I will get a little irritated . Am I right in my thinking of having a separate start stop seperate from the fused disconnect ?


    Reading about why a motor starter is used it seems like their only purpose is to allow use of small buttons instead of a large switch and as a result they can put switches anywhere they want rather than have a big switch . With this phase converter being mounted to the wall and no need for the switch to be in a tight or small location there is no need . Although a motor starter still sits in the phase converter yet with no switches ... I just don't know enough . Hopefully tomorrow will shed some light .
     
  12. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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    Well, that's why I wanted to see the schematic. I'm sure the 3 pole starter in the converter is on the output, so you can energize the 3 phase distribution panel once the converter is fully at voltage and current. I have seen some shop built converters that have such a starter and a simple spst toggle switch to energize the coil, and turn on the whole thing. That spst switch could easily be replaced with a pb station. The wiring of such does require access to the coil in the contactor, and knowing the coil operating voltage. If it is line voltage, fine, but if it is lower, and some (many?) are lower, like 24 volts.....then you will need a stepdown transformer that is controlled by the station, and is wired to the coil. There is a variety of ways to tackle this. One reason people use low voltage controls is so they can remote them. The converter can be wherever you want, and run a control circuit to where the buttons would be handy.

    As far as a separate fused d/c, I do like the idea, but it's not really a necessity if you are running power to the converter from the supply protected by proper breakers. Nothing wrong with leaving it hot, as long as the contactor controls when it actually runs. But you do want a way to power it down for service. Code normally requires a safety disconnect within so many feet, or in line of sight, but in a private shop you can do whatever you feel safe doing. In my small shop, I don't use disconnects at each machine, but they are wired back to the breaker panel. Some of the machines have their own disconnects, some do not. If I want to work on it, I simply kill the breaker. I don't do a LOTO, because it's just me. On my equipment outside, like the air compressor and air conditioner, yes, they have breakers in the panels, and they have fused disconnects adjacent to the equipment. I'll look over the link and see if I can offer anything else.
     
  13. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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    Looking at the link info, I'd say that contactor is not for control of the entire unit, but for engaging some of the balancing circuitry. I wouldn't count on it being available for what you want. If I were setting this up, knowing only what I do at this point, I'd get a 2 pole contactor, 5 hp and the PB station you have. Run your power from the service panel to it (properly breakered) and turn the converter on and off with it, and forget about a knife switch or a disconnect. You could get something that would fit in a small enclosure and mount the PB station right on it, wherever you wanted to.
     
  14. Tony Wells

    Tony Wells Administrator Staff Member Administrator

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    OK, so you feed single phase in and it just goes through and on the output terminals, there are three, with the added phase. So when you power up the unit, you simply switch on the single phase 220? If that's the case, then you certainly could use a fused disconnect (2 pole) to control it. BUT, where is the protection for the output? I would think there is some built in, or I would most certainly have something as a main breaker in the three phase panel this feeds.
     
  15. cincinnati JA

    cincinnati JA Active Members Active Member

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    Thanks Tony, I'm learning more and more as you guys provide this wonderful information. The way this converter is set up to work is the L1 and L2 leg feed into the panel seperate or daisy chain off the lugs in the converter . There is no input output separation inside this converter . And then the T3 is added . So what would the motor starter be doing on the output end ? I see wires coming off of it going to the two black capacitors on the left . And there is also a time delay involved . As far as the fused disconnect goes , I was specifically told to NOT use a breaker on this converter because of its high start amperage it draws so the motor doesn't trip the breakers or blow fuses. I'm sure you are familiar with time delay fuses . That is something I do understand lol. I really like the idea of the momentary switch but I may just swap out the pull out disconnect for the lever type/knife type fusible . I still have my millingmachine to refurbish so I gotta save some money. Unless I could get the parts I needed used for next to nothing .

    - - - Updated - - -

    Btw my electrical set up is interesting . There is 8gauge wire feeding the garage seperate from the house off a 60amp breaker which feeds a fuse box . And the garage is all wired with 12 gauge . So from the fuse panel with 30 amp fuses it goes into the fusible disconnect that holds the time delay fuses for the reasons I said in the previous post. From there the phase converter is turned on and then the output "t3" a long with L1 and L2 is fed into the 3 phase panel and from there I will hook my machines to that.
     
  16. cnczone

    cnczone New Member

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  17. cincinnati JA

    cincinnati JA Active Members Active Member

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    Btw the breaker type switch is rated for that 1/2hp shaper head so that's why it can take the amps. Here is a photo [​IMG]

    Is the momentary switch I got worth 42$ ? If its a good deal I will keep it for future projects but if not then it maybe should be returned . It was new old stock. It's a joslyn Clark pushbutton station Bul. 100 type ee std duty 600v max cat. No. 1A 3 ... Any of you guys know what that means?

    I may just go with the knife switch and be done with it .

    But I also have some questions about another piece of 3 phase equipment I have since we are on the subject of switches . It is a Allen Bradley and is its own manual starter switch all in one .

    [​IMG]

    Here is the description on the back of the cover .

    [​IMG]

    It uses N18 type heaters which calls for max fuse size 10 . Would this means it can take up to 10 amps on this fuse? I will be hooking this machine up to a 15amp 3 phase breaker . Will this be fine?

    So if I find a pushbutton station like this AB one . It should work for the converter as well right ?


    If I choose to use contractors is this what you were talking about ?

    http://www.auberins.com/index.php?main_page=product_info&products_id=164
     
  18. GK1918

    GK1918 Active Members Active Member

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    I was told not to cause of high amp start load?? You want to start & stop the RPC fed by 220 single
    phase? I like the looks of a red & green switch that has to have a relay (we all like the looks)?
    I have seen in the past push button red & green switches that are actually a knife switch. And then
    whats wrong with the ole gray D box with double 100amp breakers. My 220 has this type box next
    to my enterance door, so on the way out I shut down all 220 because my kids always leave the air
    on and the comp. will run all night. I thought I fell off the boat on this one, but rethinking I do have
    two new st/stop with green and red. When either is pushed (it does not stay) tells me it triggers
    a relay (which I have) that when closed it stays closed until stop is pushed that relaxes a coil that
    kept it closed. I Think. Ill try and look for it I know its rated 600vts. Its probably the same deal as
    on the mill control panel. Still think Id go for a simple double breaker, after all thats my shop shut down
    it takes all the machine start shock (although it is a sub box off the main breaker. I do not have RPC
    so its my guess Josh, but I have a freind that does he has just a 220 breaker on the 3Ph motor and
    a 110 common home switch on the pony 110 motor < > he flips the pony first= flips the 220 gets the
    220 running and flips off the 110 pony just like starting the old Cat Dozers. Since we last spoke I
    have not yet had any problems with my static phase and a little proof, other day had to drill a spring
    hanger none of my presses wont go that slow so the mill & the drill caught and smoked the drive
    belt. So I dont know about that 2/3 Hp thing, I got plenty of power. Sam
     
  19. cincinnati JA

    cincinnati JA Active Members Active Member

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    Well Sam I am probably super protected because I'm protected by time delay fuses which are required for my specific RPC , a fuse panel, then a breaker in the house lol. I can shut down my garage from my house of need be its 100 feet away from the house.

    Anyways about your static phase converter . The best known claim on the static converter is 70% of HP marked on the motor but that's not to say someone went crazy with some extra run capacitors and its pushing more . I just spoke with a guy who claims he is only getting 10% loss on static that he built . But again static only allows for one motor to run at one time. With my cross feed I needed at least two three phase motors to run at once needing a RPC or Solid state digital converter . I have a balanced RPC which is very very good with little power fluctuation it is no more than .5 +/- I believe . This type of RPC has no motor HP loss. An unbalanced RPC has about 10% loss . You friend has a traditional style RPC with a pony motor starting up a generator . I have a 5hp 3phase motor that needs to be started up but runs off single phase and the 3rd winding acts as a generator generating the 3rd leg . So you can see why I need certain switches and Definatly time delay fuses . The start up amps on a 5hp 3phase motor are greater than the fuses/breakers recommended for the motor so this is why you use time delay so at start up the fuses won't blow and you don't use breakers because they would just always trip.

    A balanced RPC isn't cheap so I am making sure I buy all the proper parts to hook this up to get maximum efficiency and life. This particular unit allows me to draw 15amps of three phase power so I can run a few machines at one time . When it comes to electricity I ultra respect it . I've been shocked a few times and I don't like it one bit! I also have never liked using disconnects other than to shut down power for service . It's just how I am I guess . Want things just a certain way . Probably hurts and helps at the same time hah .
     
  20. Ulma Doctor

    Ulma Doctor Moderator Staff Member Supporter

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    A balanced RPC isn't cheap so I am making sure I buy all the proper parts to hook this up to get maximum efficiency and life. .[/QUOTE]


    to the contrary,
    a balanced rpc can be achieved by adding a couple of Run Capacitors between phases.
    i recently balanced a 7.5 hp RPC for less than $35 in capacitors. it really doesn't get much cheaper.

    for reference, a 5 hp RPC can be made more efficient by adding an 80uf run cap between the generated leg and 1 hot leg.
    then add a 60uf run cap between the 2 hot legs , you'll see the voltage will be within 10% between legs loaded.
    10% is considered balanced.
     

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