[chbot] large earth pins

Wed Feb 15 00:38:05 GMT 2012

Charles
You're right about the keying thing.
Most cabling is not rated at 16A draw, so thats why its a different 
socket to ensure the wiring is adequate.
With the larger Earth pin socket, you can still plug a normal plug in.

Also commercial installations only use RCD for specific applications, so 
there is still a need for an earth pin.

mark

Charles Manning wrote:
> 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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