Single-phase Power for Motor-Generator 10EEs - Page 3
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  1. #41
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    "... At FLA run on a RPC torque was 10 Ft LBS. Wired to a static with with 72MF run cap. 9 ft.lbs. Modified per Steelman with 72MF run cap. 10 ft lbs ..."

    So, 100 percent of nameplate, just as Steelman claims.

    Great work!

  2. #42
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    Default Steelman modified motor

    Hello Peter, While true the motor put out 3.3 hp after being modified per Steelman. The same motor put out 3 hp without being modifed and run on a static converter.( some other observations) Less starting capacitance was needed after being modified. 200 vs 300. When run caps were devided between ABC, torque went down. Perhaps you could explain your formula for figuring capacitance after being modified.maybe an example. By the way I used to live in Pacific Grove, while at Ft. Ord. Bob

  3. #43
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    The formula ...

    I = 2 * π * F * C * V

    ... comes from the fundamental relation of current to frequency, capacitance and voltage.

    One generally knows the FLA rating of a motor, assuming the name plate is still intact.

    The frequency is usually 60 Hz (North America and western Japan), except where 50 Hz is employed (the rest of the World and eastern Japan).

    The voltage is, of course, a national average, usually 240 or 480 for North America.

    (2 * π = 6.28, and this constant converts from Hz to radians per second).

    Solving for C, we have ...

    C = FLA / ( 6.28 * 60 *240 )

    ... in farads, or ...

    C = ( FLA / ( 6.28 * 60 * 240 ) ) * 10^6

    ... in µF.

    C is a staring point, and the objective is to "tune" for I = FLA amps, without exceeding FLA amps. A clamp-type amp meter is quite helpful here. Fluke, or equal.

    Steelman's instructions are a guide, too, as the current setting for each overload (main/run and quadrature/start) are provided as a function of motor HP.

  4. #44
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    Thank you Peter. Bob

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    Please see ...

    Converting Monarch 10ee motor-generator 3-phase to single phase, Steelman method

    ... for a complete series of photos by another researcher on splitting the M-G's "Y-point" in order to enable accessing T10, T11 and T12 for the Steelman method.

    Actually, only T12 and T10+T11 is required, without loss of the ability to use the M-G in either conventional or Steelman configurations.

    When using the Steelman method, T10+T11 would be insulated and not used, and T12 would be brought to the start+run circuit.

    When using the conventional method, T10+T11 would be connected to T12.

    Only T12 is required if the M-G is to be limited to only the Steelman configuration.

    Peter

  6. #46
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    Henry Steelman's U.S. Patent 2,922,942 (January 26, 1960) is available for download. Pat2PDF.org is one suggested method of downloading.

    Steelman, knowingly or unknowingly, made some errors in his drawings, and in his numbering of certain parts of his inventive device.

    Whereas, in Figure 2 the "A" phase is correctly labeled 1, 4, 5 and 2, the "B" and the "C" phases are numbered inconsistent with NEMA standards.

    Whereas NEMA would have the "B" phase numbered 7, 10, 11 and 8, Steelman elected to number this phase 7, 11, 11 and 8.

    And, whereas NEMA would have the "C" phase numbered 3, 6, 9 and 12, Steelman elected to number this phase 3, 6, 9 and 10.

    Essentially, Steelman arbitrarily imposed a non-NEMA numbering system, one which is certainly consistent with the stated purpose of his inventive device, but which leads to possibly considerable confusion to those who are of a "NEMA mindset".

    It is true that 12-wire motors actually exist. But, it is also true that 11-wire motors do not!

    It is also true that Steelman's inventive device only needs 11 of those 12 wires, and a possible consequence of his mindset is his patent disclosure shows an 11-wire motor, not the more standard 12-wire motor.

    Once this apparent anomaly in understood, Steelman's patent disclosure may be more fully appreciated.

    Also, Steelman apparently did not have access to more modern potential relays, such as the 90-66 and similar relays, in which the voltage rise across the entire "quadrature" winding is sensed. Therefore, Steelman apparently elected to sense the voltage rise across only one-half of the "quadrature" winding.

    If a 90-66 were to be employed, as is our present practice, the voltage rise across the entire "quadrature" winding would be sensed for 240 volt applications, and the voltage rise across only one-half of the "quadrature" winding would be sensed only for 480 volt applications, using the same 90-66.
    Last edited by peterh5322; 02-04-2015 at 07:48 PM.

  7. #47
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    Default MG Single phase conversion "first attempt"

    Well, here we go. This past weekend I finally decided to put power to the MG after checking all the connections a million times, everything was a go at the end. In this test, only the MG was powered without the Exciter in place (i.e. no belt was installed). As soon as I turned the breaker to the ON position, the MG started right away and reached full speed within approximately one second. I kept powering OFF and ON several times to see if this was repeatable, and YES it does work. I then let the unit run for about 10 minutes and everything was normal. At this point, I was also measuring some of the voltages across certain terminals, and to my surprise, I found the voltages across both Run and Start capacitors were 406 Volts AC. I quickly power down the unit because my CAPs are rated at 400 VAC.

    The MG temperature was quite normal (i.e. not even warm). At this point I went back and checked all the connections again, and everything is in accordance with the above schematics.

    I then proceeded to test number 2, where I included the Exciter (by just installing the belt on the pulleys). When I switched the breaker ON, the MG/Exciter started normally within a second the full speed was reached, but in the next second or so, the MG made a winding-down noise and the breaker popped just after that.

    I waited a few minutes, and then repeated the test and the same thing happened.

    Now, I am quite stuck because I am not sure what could be wrong.

    Here are some of the parameters:

    The single phase supply voltage is 240 Volts
    the breaker is a two pole 20 AMPs

    The potential realay voltage is set at: 250 Volts
    The run capacitor is 60 uF 400VAC
    the start capacitors are 2X 150 uF 400VAC in parallel with each other to obtain the 300 uF.

    Before doing this modification the lathe was working with the three phase power input with no problems.

    The fact that the MG works by itself should be an indication that the internal modification was successful.

    Does anybody have experienced a similar situation?


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