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  1. JERRYROBINSON

    DC drives for shunt AND series field motors?

    Typically in your application you would have to have 3 supplies. A variable high current and voltage supply for the armature, a second low current variable supply for shunt field supply, and a high current low voltage supply for the series field. What I have seen work well for the series...
  2. JERRYROBINSON

    MV Motors

    General Electric supplies MV fuses in their combination starers for MV. Their application engineers have a check sheet to help apply these fuses based upon your starting conditions. I am certain that Siemens, ABB, and other suppliers of MV motor starters can help you. These fuses all have...
  3. JERRYROBINSON

    Part Winding Motor, Starter Timing

    More often than not, a part winding start motor is because of a mechanical issue, not electrical. It does very little to reduce inrush other than the break-away instantaneous. The time duration as stated earlier by several respondents at 2 seconds should be about the maximum setting, but...
  4. JERRYROBINSON

    Locked rotor definition

    NEMA MG1 1998.20.12.1, 20.12.2 treat this for standard. Any deviation from this should have a nametag defining the starting limitations. The lock rotor time and acceleration time ( 2 different values) are based upon Nema WK^2 limitations or the actual load, and are basically advising the user...
  5. JERRYROBINSON

    heavy duty quick connects for testing?

    In electric motor repair shops, they use alligator clips like the Welders use for ground clamps. The key is they bring the volts and amps up gradually. This would not work well for an accross the line start. There are other twist lock welding clamps that would work.
  6. JERRYROBINSON

    General Electric traction motor specs needed: GHM 838

    GE still has it's transportation factory in Erie, PA. but it is pretty much dedicated to Variable Frequency AC Traction motors. There are very few of the people who could help you left there. Romeful12 post would probably be you your best bet. There was a retired GE man local who ran the...
  7. JERRYROBINSON

    info on selecting starting resistors for series field DC motors

    I would suggest calling Huntingdon Electric, If they are still in business. They used to specialize in the split case steel mill motors which were usually series wound. Huntingdon Pa. 814-643-3921.
  8. JERRYROBINSON

    General Electric traction motor specs needed: GHM 838

    Have you checked with the GE locomotive web site? They are more cordial than you expect.
  9. JERRYROBINSON

    240V PWM to control 120V DC shunt motor

    Doubling the applied Voltage on a D.C. machine will double the RPM. Most small motors are not capable of running at double speed.
  10. JERRYROBINSON

    Hazardous Equipment Selection References

    You can consult NEMA MG1, which has some information on construction techniques, but in USA Underwriters Laboratories is the ultimate on the Hazardous locations as far as temperature limits and ignition temperatures. These are the same thermal limits as shown the the NFPA (NEC) documents
  11. JERRYROBINSON

    bench grinder motor burns when shaft is vertical

    Vertically oriented machines have a bearing to maintain centering of the laminations of the stator and rotor. Also as this is a small grinder hp, this could be a capacititor start or permanent split capacitor or a combination which might have a starting winding centrifugal switch. If the...
  12. JERRYROBINSON

    Hazardous Equipment Selection References

    N.F.P.A. publications (also know as The National electric code) covers the USA temperature and classifications. I suggest checking out your local technical book store. Other nations use different descriptions, but most I.E.C. nations see to have leaned towards a couple of different ones. If...
  13. JERRYROBINSON

    World's Largest AC Motor

    I know that NASA and Boeing aircraft both use 60,000 hp motors on their wind tunnels. We actually have in our possession the old motors off the Seattle wind tunell. It was 36,000 hp wound rotor induction motor, 10 pole. It was coupled to a 20,000 hp synchronous motor thru an eddy-current...
  14. JERRYROBINSON

    PTC Thermistors

    There is also Thermik, and Jenkins electric.
  15. JERRYROBINSON

    Traction Motor Brush Wear Problem

    SELECTIVE BRUSH WEAR CAN COME FROM SEVERAL SOURCES, AND HERE ARE JUST A FEW. A-LOCALIZED ECCENTRICITY IN THE COMMUTATOR SURFACE. B- INCORRECT BRUSH SPRING TENSION. C- EXCESSIVE COMMUTATOR TEMPERATURE. D- EXPOSURE OF THE CARBON BRUSHES TO FUMES FROM SILICONE RUBBER OUTGASSING AND ATTACHING TO...

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