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Posted by Phil Allison on July 5, 2009, 4:06 am
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"Archimedes' Lever"
"Phil Allison"
>
>>"John E."
>>>
>>>I have been asked to offer an opinion in a sensitive situation.
>>>
>>> A machinist moved his shop across town and required some rewiring
>>> (3-phase
>>> outlets, conduit, etc.) in order to locate some machines where he wanted
>>> them.
>>>
>>> He hires a guy who's not a pro (and later discovers is not insured) but
>>> has
>>> done shop wiring before and had a good attitude and track record. The
>>> guy
>>> does good work. No complaints about the quality of his work.
>>>
>>> Owner throws the switch, all works fine.
>>>
>>> The story continues 4 weeks later when the very expensive CNC fries its
>>> controller PCB to the tune of $4000.
>>>
>>> Turns out the voltage in the shop was upward of 245 and the taps in the
>>> CNC's
>>> power supply were set for 220.
>>>
>>> What is the legal and moral responsibility of each party?
>>
>>
>>** What a STUPID troll !!!
>>
>>The PSU in the CNC blew cos it was a pile of shit PLUS the design was
>>100%
>>incompetant cos it gave no protection to the delicate and expensive load.
>>
>>Bet it was old and way past use by date too.
>>
>>Piss off TROLL !!
>>
>
> Probably a good call, since modern switchers, which the DC supplies
> for these things usually are, can handle up to about 265 volts. Even a
> bit more, typically.
** Unlikely it was a SMPS based on the OP's admittedly poor and incomplete
info.
Cos SMPS do not have multi-taps for AC input voltage - PLUS if an
off-line switcher fails from overvoltage, it just blows the fuse and goes
dead.
But losing regulation and over-voltaging the load ( as was alleged by the
OP) is another scenario altogether - more often associated with old age or
the failure of one of a few critical components in the regulation loop.
..... Phil
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>"John E."