[ARC5] Dynamotor Questions

[Bob kb8tq]

Hi

Running on full wave AC, your voltage peaks are ~ 1.4 times what the motor was designed for. If y
ou go to half wave, you are up around 2.8X. 

If the device was designed for a a target of 24 and a max of 32, you are up around 2.8 x 24 = 67.2V. 
You are a bit over 2X the rated max.

When the brushes make / break on the armature, the arc has twice the max volts to “feed it”. That 
is going to result in a longer arc / more burn.

How much inductance does the beast have? That’s not really clear. If the inductance is low enough, 
twice the voltage also means twice the current. For anything that thinks P=I^2 * R, you have 4X the 
hot spot being generated. 

With a half wave, you are much more likely to pulse the magnetic field. That is unlikely to make things
like bearings happy as you slug them 60 times a second. 

Will the beast self destruct immediately? Certainly not. However it’s not going to be very happy.

Now, drop back to 24V AC half wave rectified and all you have is the field / bearing issue. That’s 
a lot less strain. 

Bob

> On Dec 18, 2023, at 5:28 PM, Hubert Miller <Kargo_cult at msn.com> wrote:
> 
> I don't understand why pulse drive would destroy a DC rated motor. The pulses are at a speed so that 
> the motor will not slow between pulses. I don't see how this is different from pulse width drive for a 
> toy motor, but i'm willing to be educated.
> -Hue Miller 
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