XPost: sci.electronics.design, sci.electronics.misc   
   From: dhky@shaw.ca   
      
   On 15/07/2014 9:48 PM, DaveC wrote:   
   >> However, in this case of a jog function- If a single phase capacitor   
   >> start single phase motor has the same starting torque as the 3 phase   
   >> motor (and with the right capacitor- this may well be done) a single   
   >> phase motor may well fit the needs-electrically-but likely not   
   >> mechanically with respect to mounting.   
   >   
   > I (OP) am concerned about jogging. The single-phase motor will be using its   
   > start winding, and the associated high current will heat the winding. Jogging   
   > means usually repeated, sometimes back-and-forward direction changes, short   
   > motor actuations.   
   >   
   > With all this jogging the centrifugal start switch will be abused over time   
   > which probably means early failure.   
   >   
   Your point is valid- I'd be less concerned about the switch than with   
   the start winding itself -second thoughts about "rms HP"   
   The motor would have to be cap start (not necessarily cap run)-yes,   
   there may be a high current at the time that the switch operates   
   Cap run optimises operation near synchronous speed -not at start.   
   How long will the motor run, when jogging? Does it get up tYour point   
   about the   
      
   There is another problem- mounting the motor- it will be larger   
   physically than the polyphase motor.   
      
   It also comes down the starting torque needed -any idea?   
   Don't rule out DC motors fed from an ordinary diode bridgr-   
   --   
   Don Kelly   
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