[chbot] large earth pins

Wed Feb 15 00:20:10 GMT 2012

Isn't it just a keying thing so you don't plug a 15A plug into a 10A socket?

You don't need a hell of a bit fault current. With good earth leakage
you only need a few mA.

On Wed, Feb 15, 2012 at 12:30 PM, Mark Atherton <markaren1 at xtra.co.nz> wrote:
> 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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>>
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>
>
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