[PSUBS-MAILIST] DC Systems Primer

[Vance Bradley]

Sent from my iPhone

On Oct 16, 2013, at 2:08 PM, Joe Perkel <josephperkel at yahoo.com> wrote:

> Dan,
> 
> What I was hoping to find was BLDC motors matching 36v 1800 - 3600 rpm, 1/2 to 2 hp range. They don't seem to be out there.
> 
> I have matched up brushed motors with those specs at both Baldor and Leeson with the appropriate face plates. But, then we are back to the same large / heavy motors at least there in the $500 range.
> 
> You have the standard motors on Persistence, what are the size and pitch of the respective props?
> 
> I'm going to just have to suck it up and draw these up with new Kort nozzles.
> 
> Thanks!
> 
> Joe
> 
> Sent from Yahoo! Mail for iPad
> 
> From: Dan H. <jumachine at comcast.net>; 
> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>; 
> Subject: Re: [PSUBS-MAILIST] DC Systems Primer 
> Sent: Wed, Oct 16, 2013 1:48:13 PM 
> 
> Those high voltage DC motors are designed for variable speed drives where the power is first line voltage AC then converted to DC through a motor controller for accurate motor speeds and torque.  They aren't practical for a battery powered system.
>  
> For battery powered systems your probably better off to stick to the lower voltage motors.  With an inverter I guess you could convert the battery power to high voltage AC then convert it to DC, but I'm pretty sure you'd find it impractical with the extra equipment. 
>  
> It's hard to beat golf cart controllers for speed regulation and there's tons of them out there.  Battery powered floor scrubbers use a variety of DC motors too.
>  
> Dan H.
>  
> ----- Original Message -----
> From: Joe Perkel
> To: Psubbers Mailist
> Sent: Tuesday, October 15, 2013 11:02 PM
> Subject: [PSUBS-MAILIST] DC Systems Primer
> 
> Since my Navy "A" school is some 30+ years ago, I need a little help in trying to understand and match up something close to Georges motors. What I dont understand is why is there such an array of DC motors in the 1 - 3 hp range with wildly varing input voltages?
>  
> If you notice those Tecnadyne thrusters have stupendous input voltages up to 330vdc. I dont understand why and need a primer on DC systems for this application. Can anyone point me to one?
>  
> What I'm trying to do is to slim down the housing, get more bollard thrust from the prop by adding a real kort nozzle, and use a mag coupling instead of a shaft seal, all else remaining essentially the same.
>  
> I want to slim down Georges T-Rex cans with similar power specs, but new and improved components, keeping the items conducive to homebuilding, like the housings and mountings, electrical penetrators, shaft seals if I cant do mag couplings.
>  
> What I've found so far http://www.baldor.com/support/literature_load.asp?LitNumber=FL1210  fractional hp and up to 3 hp @ 1800 rpm but, here again @ 320vdc !?
>  
> Whats attractive about this one is the dimensions, 6.5" on the mounting flange would fit quite nicely in the 6 nom SCH40 pipe which is 6.625"
>  
> But I dont know what im doing with regard to the input voltage / output power / torque relationship and how to match this all up correctly.  All Ive confirmed so far is that Georges motors were TENV (totally enclosed non-ventilated), 36vdc @ 1800 to 3600 rpm for 1/2 and 3 hp respectively.
>  
> Joe
>  
>  
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