Re: [CAD_CAM_EDM_DRO] Re: Toroidal transformer ratings?? What after being rectified?

Hi Dave,

>What I am unclear about is the 66% of rating for the power supplies.
>using Gecko 201's, and a 7 amp motor, with a nameplate of 1.7 votls,
>I theoretically need 12 watts, 24 watts if both phases need to be
>included. But, at the higher voltage, the supplied wattage is HUGE
>compared to the raw motor calculations.

When the motor is stationary it will be dissipating 12W or 24W as you
have calculated (ignoring iron losses). For that input you get no power
out. As soon as you start turning the motor the voltage across the coils
rises. At full speed the motor may have anything up to about 38V across
the coils. Assuming that the average current at maximum torque when
turning is 10.5A (half the time at 7A, half at 14A). This gives you a
power of 38*10.5 = 399 watts. This is a very simplified explanation as
it assumes that the current through the windings is a square wave. In
practise you would never get anywhere near this much current flowing
through the coils at full speed.

Les