[chbot] large earth pins

[Mark Beckett]

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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