Vance, The SCR controllers were primarily phase controlled with a few cycloconverters. Ken Martindale From: owner-personal_submersibles@psubs.org [mailto:owner-personal_submersibles@psubs.org] On Behalf Of vbra676539@aol.com Alex, I thought PWR was just that, on and off with variable on time. Pulse Width Modulation seems self-explanatory. All the SCR controllers we used back in the day were described to me as operating in this manner. No? Vance -----Original Message----- If the motors are controlled by PWM make sure it's done correctly, especiallyif it's regulating down from a voltage that is higher than the motor isdesigned for. Sometimes people use low speed switching to regulate motorspeeds. This is like turning the motor fully on and full off over and over,where the motor current is going to the maximum then zero over and over. Thisis like controlling the motor with a resistor, where the motor coils are theresistors. A proper PWM controller uses a high frequency and either has aninductor built in or uses the inductance of the motor coils. This creates aconstant current through the motor which is what you want.AlexOn 13-Jun-2012 Greg wrote:> Hi James,> > > > As they say - "voltage is your friend". Always bump it up if you can. Try> running the minn kotas with a PWM speed control that's being fed 36V.> > Install an amp gauge on the leads going to each thruster. Then, under load,> increase speed until you reach the maximum amount of amps that the motors> are rated for. This will be the top speed. As long as the amp rating is not> exceeded the motors will run fine. This not only makes the whole system more> efficient, but gives you more rpm on the minn kotas without burning them up.> This works especially well with brush motors that are oil filled.> > > > Upper limit on DC systems in subs from a safety standpoint is about 50 V.> > > > Greg> > > > > > _____ > > From: owner-personal_submersibles@psubs.org> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of James Frankland> Sent: Wednesday, June 13, 2012 9:21 AM> To: personal_submersibles@psubs.org> Subject: [PSUBS-MAILIST] 12 or 24v ?> > > > > > Hi All,> > > > Does anyone have any thoughts on this?> > > > My motors are 24V minn kotas. Do you think i should pass 12v through the> pods and link them up 24v inside? Or link them up 24v inside and bring that> through? > > > > 12v seems easier and i can run 12v things inside, but less efficient and> might produce more heat on the penetrators.> > > > 24v more efficient and easier on the penetrator but i'll need a transformer> inside to run 12v equipment.> > > > Ive no idea what the penetrators run at.> > > > Any thoughts?> > > > Many thanks> > James> > > -- Mailed on 25-Jun-2012.************************************************************************************************************************************************************************************************************************The personal submersibles mailing list complies with the US FederalCAN-SPAM Act of 2003. Your email address appears in our databasebecause either you, or someone you know, requested you receive messagesfrom our organization.If you want to be removed from this mailing list simply click on thelink below or send a blank email message to: removeme-personal_submersibles@psubs.orgRemoval of your email address from this mailing list occurs by anautomated process and should be complete within five minutes ofour server receiving your request.PSUBS.ORGPO Box 53Weare, NH 03281603-529-1100************************************************************************************************************************************************************************************************************************ |