Re: [CAD_CAM_EDM_DRO] Re: electro-craft servos

dpresto3 wrote:

>
>Hi John,
>I have some E543 motors, are you able to tell me what the normal
>voltage rating is for these motors (I have been told they may be 60
>volts but have not been able to confirm that) and what the peak
>amperage is (amperage under maximum acceleration).
>Regards
>David
><John.Craddock@x> wrote:
>
>
>>Kt 14.9 +/- 10% oz in / amp
>>Ke 10.5 - 11.5 Volt/1000rpm
>>Terminal resistance at 4 amps = 1.4 - 1.8 ohms
>>Electrical time constant 3 msec
>>Mechanical time constant 8 msec
>>Maximum peak torque 420 oz in
>>Maximum continuous current 3.7 amps
>>No-load current at 24 volt = 0.33 amps
>>Motor inertia = 0.008 oz in
>>Maximum continuous speed = 4000 rpm
>>Friction torque = 3 oz in
>>
>>

Max RPM is 4000 * Ke of about 11, gives 44 V for no load.
Now, if you want to deliver peak torque at that speed, you
need to add the IR drop, which is 420/Kt = 28 A * 1.6 Ohms=
44 V. So, you need 44 + 44 = 88 V to deliver peak torque
at 4000 RPM. If you don't need full torque or full speed,
you can do with less. If you will be using Gecko drives,
then your current limit is 20 A anyway. That would be
20 * 1.6 = 32 + 44 = 76 V, which sounds good for a Gecko.

Jon