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Recent content by Shortstub

  1. Shortstub

    Unbalanced Rotor Currents ?

    ed, I didn't say it wouldn't work for the delta connection. It just isn't necessary. A delta connection is already a closed circuit. However, the jumpers used between the stator terminals could influence operation depending on their size. Transform the delta to an equivalent wye. Then the...
  2. Shortstub

    Unbalanced Rotor Currents ?

    EP, You misunderstood my caveat. Line frequency parameters are only present in the "rotor" at standstill, otherwise they are at a much lower frequency. The following will explain my "inductive" reasoning (excuse the pun): My first engineering job was in an industry that...
  3. Shortstub

    Unbalanced Rotor Currents ?

    Back to the original problem! Regardless of which winding is used as the armature, and which the "rotor", and although I agree either condition will result in rotation, you are really comparing apples to oranges. If either the stator or rotor is connected to the source, its...
  4. Shortstub

    Unbalanced Rotor Currents ?

    ep, Thanks for the advisory. The problem now worsens. If you model the motor with the stator and rotor parameters interchanged, the rotor as the armature connected to a supply voltage of 400V, and the stator leads shorted, the magnetizing current is even less stable. My point is... if, prior...
  5. Shortstub

    Unbalanced Rotor Currents ?

    Re my last post: Oops, arith"O"... should be ~12%, not 8%!
  6. Shortstub

    Unbalanced Rotor Currents ?

    I retract my original query. Running the stator @ 8% (400/3300V)precludes development of a stable magnetizing flux wave. This will affect rotor current.
  7. Shortstub

    Unbalanced Rotor Currents ?

    Edison123, Does the rotor-current unbalance reduce as the motor is loaded?
  8. Shortstub

    Is this ferroresonance ?

    Two scenarios you may wish to explore: 1) The NER may not be effectively-earthed! 2) Assuming the VTs are open-delta connected, the secondary voltage burden circuit(s) may be causing a sufficient overcurrent forcing the VT(s) into saturation. Check the their voltage kneepoint!
  9. Shortstub

    Power factor correction.

    What was capacitor's size?
  10. Shortstub

    Electrical rotating device for turning 10kg box 180 degrees

    Weight or mass?
  11. Shortstub

    Large Induction motor - Capacitor start vs Reactor start

    IA = Transactions on Industrial Applications! BTW, Rraghunath, you realize that the capacitor method requires that the capacitor be quickly de-energized upon reaching full speed.
  12. Shortstub

    Large Induction motor - Capacitor start vs Reactor start

    rraghunath, Have you considered using an Automatic-Load-Tap-Changer in the step-down transformer? Or, how about a Line-Type, Voltage-Step-Regulator in the motor's feeder. Both methods have the advantage of "closed-transition!" In addition an LTC in the transformerd primary will be...
  13. Shortstub

    Factors Effecting Motor rating for LV/MV system

    Essentially the availability of electrical components and devices to effect proper installation at each voltage level. However, in most cases it boils down to copper reduction! As an example I once studied the economic impact of 830 V distribution for a grass roots refinery! The savings was...
  14. Shortstub

    #rd Harmonics from Steam Turbine Generator

    Sjvanhecke, some additional food for thought. Since there is only a single element intentionally connecting the system's neutral and ground/earth, then two conditions must exist to cause a current to flow in the neutral... a source of voltage-magnitude unbalance, and a second connection between...
  15. Shortstub

    #rd Harmonics from Steam Turbine Generator

    Sjvanhecke, You have yet to state a neutral current magnitude!
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