Re: [CAD_CAM_EDM_DRO] Re: Mariss' power supply circuit

"John H. Berg" wrote:

>
> I've been reading these comments on braking techniques for servos/steppers,
> and though I don't think any of the conversations to date have reached
> sufficient current levels, one needs to watch the peak current level in
> permanent magnet motors so as to not exceed the demaginazation current
> level. This is the point at which the magnetic field in the motor becomes so
> high that it can destroy/demagnatize even rare earth magnets. This problem
> is most common in emergency stop situations where a resistor or short is
> used to brake a motor.
>

Mariss:

Speaking of current levels in DC Servo motors, the ones I have are rated
90VDC at 7.6 amps continuous (giving 300 oz*in at up to 2500 rpm). Of
course I only run them at 75 VDC on my power supplies.


However, they can surge for brief periods (5% duty cycle) to many times
that amperage. I presume the limit is mostly heat-dissipation related.


Should I set the G340 at 20 amps (so the full 20 amps is available for
infrequent surges), or should I set the G340 closer to 7.6 amps (perhaps
you have made provisions for brief surges over the maximum set on the
potentiometer).

Thanks in advance, as always

Doug Fortune
http://www.cncKITS.com

























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