3 Phase Induction Generator Connections?

Discussion in 'The Projects Forum' started by GeneratorFan, Dec 5, 2014.

  1. GeneratorFan

    Thread Starter New Member

    Aug 29, 2013
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    Evening, I have just got a nice Dayton 2hp industrial motor for $25 bucks. This motor has never been connected to a supply and none of the holes are punched out. I have done a little research and it turns out this motor was like $400 bucks brand new. I think I got a deal on it!

    I bought this motor for the sole purpose of building a nice induction generator. So I have a few questions on the connection methods.

    This is unit is a Tri Voltage motor 200-240-460 volt motor. There is 9 wire leads in the connection box.

    I want to bring out the other three wires which would be wires 10,11,12. If I am not mistaken the correct order of connection for these taps would be as follows?

    I have 9 leads on the stator, numbered 1-9. If I use a meter to find the circuit from lead #7 to the end of one of the wires from the star point I should be able to label it as lead #10. the next circuit from lead #8 to one of the other star point wires will be #11. the circuit from lead #9 to the last star point wire will be #12.

    Now my question? I would like to get the maximum amperage possible at 120 volts only. I have been searching through the connections options drawn up here and I see two possible connection methods.
    http://www.anoldman.com/power_system...enerators_work

    1.) Low Delta should in theory produce 120 volts only if the prime mover is held at the correct speed which will be about 1800 RPM from a quick calculation. Induction machines having to be driven 50-75 RPM faster than they operated as a motor.

    2.) Double Delta but according to the aforementioned site this particular connection method is said to be troublesome. I am not sure I follow on this? Since this is a conversion from a induction motor there is no regulator to worry about.

    3.) Low Wye would be another option, but I feel I would not be able to tap the greatest potential of the winding set with this scheme.

    4.) The final configuration is called a zig-zag, and is most commonly used when residential 120v/240v is needed from a 3-phase generator.

    Zig-Zag would be similar to Double Delta, and would possible offer the advantage I am looking for which is to tap the greatest given potential of the coils.

    I ordered a copy of "Motors As Generators for Microhydro Power" By Nigel Smith. This book is very good, but since we have a different power system in North America, I have come to the conclusion that the C-2C connection method is useless for our split phase 120-240 system.

    Now I have looked at the information posted here but I am totally in the dark I am afraid. http://www.fieldlines.com/index.php?...8107.msg824177

    What I am looking for is basically a step by step guide to connecting up all 12 wires once I bring out the other three wires on this 9 wire machine.

    The connection methods of interest are the Low Delta. Double Delta, Zig-Zag connection methods from a 3ph 12 wire generator.

    Once the winding connections are sorted, Then I would like someone to explain how to connect up the excitation capacitors since this is a induction generator conversion.

    I am under the impression if the motor is connected Wye, The capacitors for excitation are connected delta?

    If I connect the motor Delta, Then doesn't the capacitors have to be connected Wye?

    I spent $80 bucks locally at a AC shop for 4 50uf 450V AC Run caps.

    P.S. I realize all the flaws with this type of generator. This discussion is supposed to be about connections of the 3 phases. I do not want 10 post of rubbish bashing induction generators. That is useless crap to me!

    Robert
     
  2. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Well since we can't criticize the replies you will get will be pretty minimal. :p

    Now that said if you set it up as a simple 12 wire delta for 120 VAC output you should be able to get it to work just fine. Ideally you will use two of the phases for the capacitive excitor bank and the third one for your power out.

    Something like this.

    L1 to L2 power out.
    L1 - L3 Capacitor.
    L2 - L3 Capacitor.

    As far as getting your output voltage and frequency right the best way to do it is to adjust your RPM's until you get the frequency into the range you want like 60 Hz +- 5 from no load to full load is a good range to shoot for the adust your excitor capacitor bank values until you get your 120 VAC +- 10% no load to full load to work if possible.

    BTW it may be necessary initially charge up the iron core by putting 12 or so volts DC into the output circuit for a second or two if the motor wont self excite once spun up.
     
    Last edited: Dec 6, 2014
  3. GeneratorFan

    Thread Starter New Member

    Aug 29, 2013
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    0
    tcmtech, Is that wiring configuration for 12 lead connection or the stock 9 leads? I really just did not want a post full of crap, So bashing is not allowed. I have already run in to that with this same discussion elsewhere on the web.

    Robert
     
  4. tcmtech

    Well-Known Member

    Nov 4, 2013
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    12 lead with all winding sets being used for both the power and the excitor work.
     
  5. GeneratorFan

    Thread Starter New Member

    Aug 29, 2013
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    So, I just use two of the capacitors out of the 4 I bought and wire it with the power output wires being L1-L2 and the caps on L1 - L3 and L2 - L3? Should I earth L2 to the frame of the generator as my neutral and ground?

    Tcmtech, Do you think this will do 120 volts or more like 200 volts? Seems like you have some experience with motors.

    Robert
     
  6. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Yea I used to play with this stuff a lot so I have a fairly reasonable understanding of how to do it.

    No idea what voltage you will get out of it until you hook it up and a lot of its just guess work until you find the right combination of capacitance to get the voltages you want.

    When you get your capacitance levels right on both sides whatever winding configuration you set it up for will have pretty close to the correct voltage so if you set it up as a 12 lead 120 volt delta you should get pretty close to 120 volts.

    Might need a load of capacitance to do it though!
     
  7. shahin123

    New Member

    Sep 3, 2013
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    I Want to know details what is Induction motor/Generator.
     
  8. tcmtech

    Well-Known Member

    Nov 4, 2013
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    It's just a induction motor, usually three phase, being used as a generator by using a set of capacitors to work as a excitor on a set of windings that are not being for the output power.
     
  9. GeneratorFan

    Thread Starter New Member

    Aug 29, 2013
    4
    0
    tcmtech, If this equation is true then one can expect about 144 volts output correct? This is not too bad considering my coleman powermate 4kw set runs the same no load.

    240V / 1800 RPM = 0.1333
    1875 RPM * 0.1333 = 250 V
    Y-D conversion factor = square root of 3 = 1.73
    250 V / 1.73 = 144 V

    These figures are by Steven Sparweb http://www.sparweb.ca/3_Gen_MoCo/Conv.html

    Robert
     
  10. tcmtech

    Well-Known Member

    Nov 4, 2013
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    The amount of capacitance in the exciter circuit can be adjusted to change the working voltage to some degree. Its rather trial and error doing so but it will work.
     
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