24 volt or 12 volt

[Capt Kangeroo]

I was given a Robertson autopilot pump that I intend to rebuild as a spare however it is missing the data plate. I found a pic on google which indicated it was a Robertson / Simrad RPU series but noted it was offered in two voltages 24 & 12. I tried matching the tech drawings on the various RPU models to what I have but this was inconclusive.

I have not powered it on 12V yet but assuming a 24V motor will even run on 12V I do not know what speed it is supposed to spin so this will not likely tell me much.

Anyone here aware of any tricks to figure out the voltage of DC motors? All thoughts welcomed.

 

[twistedtree]

Humm, interesting question. Do you have the same pump currently in a 12V version? If so, I'd try measuring the resistance across the power leads and compare. The measurement needs to be done with at least one of the leads disconnected from anything else to ensure you aren't also measuring something else that's attached. If it's a 24V pump, I'd expect the resistance to be double the 12V's resistance. But that assumes all the impedance of the motor is resistive, and I'm not certain that's the case. My knowledge of motors is weak enough to be unsure. Hopefully someone else will know more.

 

[Capt Kangeroo]

TT, I thought similar but unfortunately my existing Robertson unit has a much smaller motor case. This could be an indicator the spare is 24V or that simply it is a more powerful motor than mine.

 

[caltexflanc]

Just to mess with you, they also made them in 32 volt; I had one myself. Take it to a long time electronics seller there in Florida and they can likely ID it for you. Where are you located?

 

[Capt Kangeroo]

Thanks a heap George, I was confused enough