<DIV style="font-family:Arial, sans-serif; font-size:10pt;"><DIV>Oh, thought maybe it could be reading wrong because of the placement of the strobe indicator.</DIV><DIV> </DIV><DIV>Brian<BR><BR>--- personal_submersibles@psubs.org wrote:<BR><BR>From: hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><BR>To: Personal Submersibles General Discussion <personal_submersibles@psubs.org><BR>Subject: Re: [PSUBS-MAILIST] power converter<BR>Date: Thu, 28 Apr 2016 02:59:40 +0000 (UTC)<BR><BR></DIV><DIV style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);"><DIV><SPAN>Brian,</SPAN></DIV><DIV><SPAN>I have a manual tachometer for my antique gas and steam engines.</SPAN></DIV><DIV><SPAN>Hank</SPAN></DIV> <DIV><BR><BR></DIV><DIV style="display: block;"> <DIV style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <DIV style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <DIV dir="ltr"><FONT face="Arial" size="2"> On Wednesday, April 27, 2016 6:37 PM, Brian Cox via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<BR></FONT></DIV> <BR><BR> <DIV><DIV><DIV><DIV style="font-family: Arial, sans-serif; font-size: 10pt;"><DIV>Hank, How are you measuring the rpm ?</DIV><DIV> </DIV><DIV>Brian<BR><BR>--- personal_submersibles@psubs.org wrote:<BR><BR>From: hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><BR>To: Personal Submersibles General Discussion <personal_submersibles@psubs.org><BR>Subject: Re: [PSUBS-MAILIST] power converter<BR>Date: Wed, 27 Apr 2016 22:52:52 +0000 (UTC)<BR><BR></DIV><DIV><DIV style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);"><DIV dir="ltr"><SPAN>The thrusters are from PC1402 and Triton is working on it right now.</SPAN></DIV> <DIV><BR><BR></DIV><DIV style="display: block;"> <DIV style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;"> <DIV style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <DIV dir="ltr"><FONT face="Arial" size="2"> On Wednesday, April 27, 2016 3:45 PM, via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<BR></FONT></DIV> <BR><BR> <DIV><DIV><DIV><FONT color="black" face="Arial, Helvetica, sans-serif" size="3"><FONT size="3">Who has which sub that the thrusters came from?</FONT><BR>
<BR>
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</FONT><DIV><DIV style="color: black; font-family: helvetica, arial; font-size: 10pt;">-----Original Message-----<BR>
From: hank pronk via Personal_Submersibles <personal_submersibles@psubs.org><BR>
To: Personal Submersibles General Discussion <personal_submersibles@psubs.org><BR>
Sent: Wed, Apr 27, 2016 11:26 am<BR>
Subject: Re: [PSUBS-MAILIST] power converter<BR>
<BR>
<DIV>
<DIV>
<DIV style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);">
<DIV><SPAN>Thank you Sean and everyone who helped.</SPAN></DIV>
<DIV><SPAN>Yipppeee, I just got an e-mail from Triton Submarines and they said they have the original sub my thrusters came off in the shop. Turns out the 14 series ran 36 volt thrusters. So Steve was correct and they are 36V after all, providing they are original to that sub. Man O Man they are </SPAN>helpful at Triton. I have asked them questions over the years, and they are always happy to help and quickly also.</DIV>
<DIV>Hank</DIV>
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<DIV dir="ltr"><FONT face="Arial" size="2"> On Wednesday, April 27, 2016 7:40 AM, Sean T. Stevenson via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> wrote:<BR>
</FONT></DIV>
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<DIV dir="ltr">Hank - these motors of yours are DC motors, correct? If so, the only way to control them is by varying the applied DC voltage, either directly or by approximating it with pulse width modulation (a DC motor controller) which outputs the full rated voltage (120 V?) for some percentage of time (the duty cycle), at a period switched at a relatively high frequency.</DIV>
<DIV dir="ltr">Either way, you need to step up from your 48 VDC bus voltage. There are three ways to do that. </DIV>
<DIV dir="ltr">1). You can go to more batteries in series for a higher DC bus voltage. I like this solution because you get away with smaller wires and have less voltage drop over distance, but it does mean that you need to use regulated power supplies for house loads instead of making direct battery connections to 48 VDC appliances. Also, DC voltage is dangerous stuff, so make sure the bus lines are protected from contact, fused or with appropriate breakers etc.</DIV>
<DIV dir="ltr">2) You can use a DC-DC converter of an appropriate power rating for your motors. Not sure what it would cost, but this is the simplest and cleanest solution.</DIV>
<DIV dir="ltr">A converter is essentially a VFD in inverse. To step up any voltage, that voltage must be AC (transformers only work with varying electric / magnetic fields). A transformer operating at typical AC mains frequencies is large and inefficient. As the AC frequency goes up, the size and heat dissipated in components goes down. I'm simplifying a bit, but the DC-DC converter essentially uses some complicated switch mode electronics to invert your 48 VDC to an AC voltage at a very high frequency (kHZ or MHz), then steps that AC voltage up in what is effectively a transformer circuit (to e.g. 170 VAC), and finally rectifies the stepped-up AC voltage back to DC (e.g. 120 VDC).</DIV>
<DIV dir="ltr">3) Use a M/G set. 48 VDC motor directly connected to an AC generator and rectifier to produce DC at the higher voltage. Old school and inefficient, but it works.</DIV>
<DIV dir="ltr">At this point, I might just look at the cost of replacing the motors you have with 48 VDC equivalents.</DIV>
<DIV dir="ltr">FYI, in my own design, I am using a high voltage DC bus (647 VDC), but that voltage only exists in the battery compartment which is an isolated space flushed with sulfur hexafluoride in order to eliminate fire risk and prevent arcing. The battery feeds the DC bus of a VFD, bypassing the rectifier stage which would otherwise be fed by an AC generator or shore power for charging. The VFD outputs variable frequency AC at 440 V, feeding an asynchronous induction motor connected to a hydraulic pump, which outputs to a common pressure line in parallel with a number of accumulators for energy storage. All of the vessel thrusters and actuators are hydraulic, commanded by servo or proportional valves as appropriate. Only 24 VDC is present in the manned compartments. The hydraulic system is inefficient compared to pure electric, but capable of delivering high power in small form factors. I get around some of the efficiency problem by relying on the accumulators so that t
h!
e pump
isn't running all the time.</DIV>
<DIV dir="ltr">Sean<BR>
</DIV>
<BR><BR>
<DIV>
<DIV>On April 27, 2016 6:24:26 AM MDT, hank pronk via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> wrote:<BLOCKQUOTE style="margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;">
<DIV style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);">
<DIV><SPAN>Hi Kieth,</SPAN></DIV>
<DIV dir="ltr"><SPAN>If I use my 3,000W inverter do I not need a rectifier? could I still reverse them? </SPAN></DIV>
<DIV dir="ltr"><SPAN>Thank you</SPAN></DIV>
<DIV dir="ltr"><SPAN>Hank</SPAN></DIV>
<DIV><BR><BR></DIV>
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<DIV dir="ltr"><FONT face="A! rial" size="2">
On Tuesday, April 26, 2016 9:48 PM, k6fee via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> wrote:<BR></FONT></DIV>
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<DIV>
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<DIV>Most inverters these days are 90 - 98% efficient at converting </DIV>
<DIV>DC to AC. You would only need a 100,000 mfd cap to handle smoothing the DC ripple to acceptable levels to 50 amps and they rarely go south (fingers crossed) in my experience.</DIV>
<DIV><BR></DIV>
<DIV>With that said having 120vdc direct from a battery bank is the preferred option.</DIV>
<DIV><BR></DIV>
<DIV>Keith T.</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV>
<DIV style="color: rgb(87, 87, 87); font-size: 85%;">Sent from my Verizon, Samsung Galaxy smartphone</DIV>
</DIV>
<DIV><BR></DIV>
<DIV>
<DIV style="color: rgb(0, 0, 0); font-size: 100%;">
<DIV>-------- Original message --------</DIV>
<DIV>From: Stephen Fordyce via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> </DIV>
<DIV>Date: 4/26/16 7:45 PM (GMT-08:00) </DIV>
<DIV>To: Personal Submersibles General Discussion <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> </DIV>
<DIV>Subject: Re: [PSUBS-MAILIST] power converter </DIV>
<DIV><BR></DIV>
</DIV>
<DIV dir="ltr">
<DIV>Hi guys,</DIV>
<DIV>Getting it to AC should be more straightforward in terms of being able to get a standard product, but still needs a pretty big/expensive inverter. The DC rectifier could work but again for the currents involved the capacitors required for a smooth output would have to be huge, and it's another significant exercise/stuff to go wrong. Plus it's probably all quite inefficient (I wouldn't be surprised if you lost 20% of the electrical energy just through the conversion).</DIV>
<DIV><BR></DIV>
<DIV>Cheers,</DIV>
<DIV>Steve</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
</DIV>
<DIV><BR>
<DIV>On Wed, Apr 27, 2016 at 12:18 PM, k6fee via Personal_Submersibles <SPAN dir="ltr"><<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>></SPAN> wrote:<BR><BLOCKQUOTE style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;">
<DIV>
<DIV>Another option is to use an off the shelf 48v to 120v ac inverter then use a bridge rectifier to take it back to DC. To get away from a cooling fan the heat sink could be mounted to the hull to dissipate the heat and make it quiet.</DIV>
<SPAN></SPAN>
<DIV><BR></DIV>
<DIV>Keith T.</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<BR></DIV>
<DIV>
<DIV style="color: rgb(87, 87, 87); font-size: 85%;">Sent from my Verizon, Samsung Galaxy smartphone</DIV>
</DIV>
<DIV><BR></DIV>
<DIV style="color: rgb(0, 0, 0); font-size: 100%;"><SPAN></SPAN>
<DIV>-------- Original message --------</DIV>
<DIV>From: Stephen Fordyce via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> </DIV>
<DIV>
<DIV>
<DIV>Date: 4/26/16 6:30 PM (GMT-08:00) </DIV>
<DIV>To: Personal Submersibles General Discussion <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> </DIV>
<DIV>Subject: Re: [PSUBS-MAILIST] power converter </DIV>
<DIV><BR></DIV>
</DIV>
</DIV>
</DIV>
<DIV>
<DIV>
<DIV dir="ltr">Hi
Hank,</DIV>
<DIV>I've dabbled a little bit in (small!) DC converters and my guess is that a converter that will do the current you're after will be expensive/large/complex and probably generate a significant amount of heat. Also seems like an obscure set of operating conditions that will be hard to find off the shelf. </DIV>
<DIV><BR></DIV>
<DIV>You've probably thought about it, but splitting the battery bank and rewiring part of it to supply 120VDC is probably the easiest low-tech solution if you have enough cells to put in series and achieve the higher voltage. You would get some nice redundancy there too if you have 2 battery banks controlling different thruster sets.</DIV>
<DIV><BR></DIV>
<DIV>As an aside, I suspect 48VDC is pretty lethal, but 120VDC even more so.</DIV>
<DIV><BR></DIV>
<DIV>I just saw Alan's email come through - running it off lower voltage is
definitely an option, but depends on the sort of motor. Ie. a brushed motor speed is proportional to the voltage applied (so running at 48VDC would give you less than half speed) - no idea what the Perry ones would be, but being older they may well be brushed. Brushless motor speed is proportional to frequency applied by the controller. In both cases torque is proportional to current which is proportional to heat generated. So the greater the current in your wires, the more heat needs to be dissipated, and if it's not then something will burn out - probably the thin layer of insulation on the motor windings. The trouble is dissipating the heat from the inner windings (it has to pass through the outer windings, which are producing their own heat) - but like Alan said, if you've got it oil compensated that will help a lot with heat dissipation. The thermal conductivity of !
oil is
~6x that of air (and water ~24x air), although the heat transfer is not quite as simple as that.</DIV>
<DIV><BR></DIV>
<DIV>I'm also pretty sure that the motor will have an inherent resistance that will be designed into it appropriate to the nominal voltage and current, and related to the size of the wires (ie. as Hank pointed out, thinner wires for high voltage as less current is required). So if you apply less voltage to the same resistance, it will draw less current - ie. I don't think you will be able to get extra current into the motor at lower voltage. Not quite that simple, but you get the idea.</DIV>
<DIV><BR></DIV>
<DIV>(that was mostly dredged up from memories of a university subject I did on electric motors a long time ago, feel free to correct me!)<BR><BR></DIV>
<DIV>Cheers,</DIV>
<DIV>Steve</DIV>
</DIV>
<DIV><BR>
<DIV>On Wed, Apr 27, 2016 at 10:18 AM, hank pronk via Personal_Submersibles <SPAN dir="ltr"><<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>></SPAN> wrote:<BR><BLOCKQUOTE style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;">
<DIV>
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<DIV><SPAN>Thanks" Kieth,</SPAN></DIV>
<DIV dir="ltr"><SPAN>I started to that but I have no idea if one system is better than another.</SPAN></DIV>
<DIV dir="ltr"><SPAN>Hank</SPAN></DIV>
<DIV><BR><BR></DIV>
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<DIV dir="ltr"><FONT face="Arial" size="2"> On Tuesday, April 26, 2016 6:11 PM, k6fee via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> wrote:<BR></FONT></DIV>
<BR><BR> </DIV>
</DIV>
<DIV>
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<DIV>
<DIV>
<DIV>
<DIV>Hank,</DIV>
<DIV><BR></DIV>
<DIV>You want a dc-dc converter, just Google it.</DIV>
<DIV><BR></DIV>
<DIV>Keith T.</DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV><BR></DIV>
<DIV>
<DIV style="color: rgb(87, 87, 87); font-size: 85%;">Sent from my Ve!
rizon,
Samsung Galaxy smartphone</DIV>
</DIV>
<DIV><BR></DIV>
<DIV>
<DIV style="color: rgb(0, 0, 0); font-size: 100%;">
<DIV>-------- Original message --------</DIV>
<DIV>From: hank pronk via Personal_Submersibles <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> </DIV>
<DIV>Date: 4/26/16 4:53 PM (GMT-08:00) </DIV>
<DIV>To: Personal Submersibles General Discussion <<A href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</A>> </DIV>
<DIV>Subject: [PSUBS-MAILIST] power converter </DIV>
<DIV><BR></DIV>
</DIV>
<DIV style="color: rgb(0, 0, 0); font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255);">
<DIV>HELP,,,</DIV>
<DIV>Turns out my !
Perry
thrusters are not 36V but 120 Vdc. I can only manage 48V dc from Gamma's battery bank. Can I step the voltage up with something.</DIV>
<DIV>Hank</DIV>
</DIV>
</DIV>
</DIV>
</DIV>
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