will commutator flashover at 36VDC?

[artym]

I'm hoping to use a 12vdc@150amp rated intermittent-duty series winch motor on 36vdc @150a for 5 or 10 seconds.

(The motor looks a lot like a starter motor for an automobile)

I think it's designed to run at about 2500 rpm @12v w/ rated load, but I'm looking for 7500rpm w/rated load.

I don't know how many bars on the commutator, but is there a rule on volts/bar?

 

[edison123]

artym,

Your proposal to run the 12 VDC motor at 36 V and at 3 times RPM would destroy the motor due to

1. There is definitely a cap on the volts/bar. So, increasing the voltage by 3 times will cross this limit and cuase severe arcing.

2. As you increase speed to three times, the rate of commutation increases drastically, causing severe arcing again.

3. Your rotor will not withstand 3 times rated speed due to mechanical stress.


I have converted 230 Volts / 1800 RPM Motors to 440 Volts / 900 RPM by redesigning armature winding. But never, higher voltage with higher speed.

 

[jbartos]

Suggestion: The motor running at the higher speed than rated speed at the rated load is overloaded since Pwatt=Wrad/sec x Tn-m

 

[artym]

I left out some info here:

Longevity and reliabilty aren't too critical for this app. (I guess they couldn't be for something running at 300% it's intermittent rating!)

I may have a few precedents:

The "Low Rider" jumping cars are barred from using hydraulic accumulators, so they run similar (maybe 24v) motors on 48 or 72v at great overload&overspeed.

(Also, Charles Kettering did OK overloading DC motors)

 

[jbartos]

Suggestion: Please notice that the off-the-shelf motors are not designed and tested for overloads deviating from industry standards. Motors may vary from the manufacturer-to-manufacturer when it comes to overloads depending how much of an extra design margin the manufacturer chose to add.
Any custom motor may be engineered, designed and built for excessive performance conditions far exceeding industry standards. However, some parameters may or may not meet the industry standards, e.g. motor efficiency