Re: control of 24VAC motor?
joe_d_builder@xxxxxxxxx wrote:
> I really don't have the specs as I haven't bought the unit yet (need to
> know if it will do what I want first). Here's the unit I'm looking at:
>
>
http://www.21best.com/21_best/electronic/security/video/pan_tilt/for_sale_.html#Weatherproof
>
> I saw a similar item here that appears like it can have the speed
> varied:
>
> http://www.minkingcctv.com/en/product/products_tk15.htm
>
> Though this may have completely different motors, etc. They're all on
> Chinese New Year right now or I would try to ask them.
>
> Do these sites give any more clues as to whether it can be speed
> controlled (and hopefully speeded up a bit since the rotation is a
> little slow for what I'm after)?
>
> Thanks a bunch folks!
>
> Joe
>
>
>
>
> cs_posting@xxxxxxxxxxx wrote:
>> Tim Wescott wrote:
>>
>> > The motors are probably 2-phase induction machines with a capacitor (or
>> > resistor) that gets switched to reverse the rotation. If this is the
>> > case then there really isn't a speed control (other than possibly
>> > resistively loading the motor to reduce the available torque). Control
>> > of such a motor could be as simple as using the current control head to
>> > building a variable-frequency drive connected directly to the motor.
>>
>> Unless there's some mechanical reduction to the drive I doubt they are
>> normal induction motors.
>>
>> They might be some kind of brushless servo or synchronous motor though.
>> A lot of the lines blur - you can argue that a permanent magnet
>> synchronous motor *is* a stepper motor.
>>
>> If they are induction motors with some kind of reduction drive then
>> your variable frequency drive idea sounds good - really this isn't that
>> far off from what the other drivers might look like, just likely lower
>> power with the mechanical reduction in there than would be needed for
>> even holding on a direct drive application.
>>
>> We need to know what the motors are. What do the data plates say?
>> Model number? Specs? On what basis did he decide they are 24v ac
>> motors?
>
Directly from the spec *** the pan/tilt is multi speed (means very likely
a stepper inside) thus, it has some control electronics inside. If you
want higher speed movement contact the factory or find an alternate vendor
or three.
--
JosephKK
Gegen dummheit kampfen Die Gotter Selbst, vergebens.
--Shiller
.
