[chbot] large earth pins

Tue Feb 14 23:30:55 GMT 2012

Hi Mark,

Yup, I realise that, but on the 15A plug the blades that carry live 
and neutral are the same size as the regular ones !

Since L&N are doing the bulk of the work, why not polarize the 
connector by making these two blades larger ? There is then of course 
the question of how to manage fault current through the 
big-green-wire, maybe all three should be larger ?

All a bit late to change now...

Are you going to be joining us in Monday ?

-Mark

At 12:10 p.m. 15/02/2012, Mark Beckett wrote:
>Mark
>The reason the earth pin is larger is because its a 16A plug.
>Normal sockets are only 10A.
>
>There are 15A outlets available and usually have a /15 after them ie 
>691/15 single vertical or 692/15 double.
>
>mark
>
>Mark Atherton wrote:
>>Hi All,
>>
>>A mate just gave me a pair of power supply units out of a Dell 
>>PowerEdge Blade Rack Server.
>>
>>The point of interest being that DC is generated at an intermediate 
>>rail, and regulators local to the CPUs convert to the much lower 
>>required voltages. This saves on I2R losses associated with carting 
>>high currents around the motherboard.
>>
>>Given that the intermediate rail in question is 12 volts this could 
>>be useful. Not entirely sure what to do with the associated 77 
>>amps, but that should fix the occasional current limit that my 12V 
>>/ 25A psu hits.
>>
>>Below are some notes sent to the fellow should they be of interest.
>>
>>'Re-purposing' is such a PC phrase, so maybe this should be 
>>re-porpoising, since I had a whale of a time...
>>
>>-Mark
>>
>>>Hi Andrew,
>>>
>>>Thanks for the two Dell ASTN 7000245 SMPSUs; one worked, the other 
>>>was DOA - it was disassembled to explore the design. Here are some notes:
>>>
>>>*_Power Inlet_*
>>>The power inlet is of type IEC 60320 C20, which mates with the IEC 
>>>60320 C19 power cord ( Jaycar, 
>>>http://www.jaycar.co.nz/productView.asp?ID=PS4180 , $24 with trade card).
>>>
>>>The associated Jaycar NZ wall plug isn't what it seems, the ground 
>>>blade is about 40% wider than usual, so will not go-in-the-hole without filing.
>>>
>>>Disassembly of the PSU guts is non-trivial, I would not recommend 
>>>trying to replace the plower inlet something more available like 
>>>the IEC 60320 C14.
>>>
>>>And of course Wikipedia has details of the IEC60320 spec 
>>>http://en.wikipedia.org/wiki/IEC_60320 (was IEC 320).
>>>
>>>There is a green indicator near the power inlet indicating active AC.
>>>
>>>*_DC output_*
>>>There is quite a community out there who use these units to charge 
>>>batteries for R/C applications, with a photo of the 3 pins than 
>>>need to be linked to enable power 
>>>http://www.rcgroups.com/forums/showpost.php?p=17653072
>>>
>>>Sites include http://www.helifreak.com/showthread.php?t=361840 I 
>>>am amazed / impressed / appalled with the ingenuity of the enclosure
>>>Outputs are floating, so they can be wired in series, should you 
>>>need 24, 36 or 48V at 77 amps (!)
>>>
>>>There are a couple of indicators by the handle showing DC 
>>>available and DC enabled.
>>>
>>>Output connector is a 'real one' (rather than a massively wide PCB 
>>>connector with gold fingers).
>>>
>>>*_Design_*
>>>It is obviously worth waiting some time before poking around 
>>>inside a recently powered up Kilowatt PSU (!).
>>>
>>>All a bit jammed-in-the-box, so exploring the busted unit took a 
>>>couple of attempts to untangle some internal wiring looms - these 
>>>were bent around heatsinks and there is a PCB mounting screw 
>>>hiding under the AC power inlet (still haven't figured out how to 
>>>get at it easily).
>>>
>>>The dual redundant PCB you gave me had a an I2C selector on it, so 
>>>I was expecting the some associated instrumentation inside the 
>>>SMPSU units (output current, voltage etc), but no sign of any ADCs 
>>>which rather surprised me (similar SMPSUs did have SDA and SCL brought out).
>>>
>>>Output heatsink is a blown rectangular tunnel of copper sheet with 
>>>TO-263 power devices (Schottky rectifiers) soldered to it and a 
>>>flat extruded heatsink attached using (something like) epoxy 
>>>putty. Outputs capacitors and toroidal output chokes are also 
>>>within this tunnel. Force air cooling of capacitors is becoming 
>>>less alien to me the more often that I see the practice...
>>>
>>>Conversion efficiency appears to be quite low ( I have seen quoted 
>>>figures in the ~85% arena), this seems typical of SMPSUs of this vintage.
>>>
>>>Fan noise is tolerable, given their large-ish size, and relatively 
>>>slow speed (same can't be said for 1U PSUs I have played with).
>>>
>>>*_Overall_*
>>>Like similar PSUs, not really reparable, hence the desire to have 
>>>a couple spare units.
>>>
>>>Lots learned from this exercise, please put any similar designed 
>>>units aside to be poked at.
>>>
>>>Regards,
>>>
>>>Mark
>>------------------------------------------------------------------------
>>
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