On 6/27/2006 8:05 AM, Carl Lowenstein wrote:
On 6/26/06, Tracy R Reed <[EMAIL PROTECTED]> wrote:
Carl Lowenstein wrote:
> Not necessarily -- the current in the connector could stay at 20A
> while the effective contact resistance goes up from 0.01 ohm to 0.1
> ohm, say. The voltage drop across the contact would increase from
Wouldn't the higher resistance serve to limit the current?
Suppose the total current is 20A. This means that the effective load
resistance is 6 ohms. An initial increase of contact resistance from
0.01 to 0.1 ohms is does not significantly decrease the current. Of
course as the contact finally melts its surrounding plastic and goes
away, the current is limited (to zero).
My guess is that there was a poorly done connection where the one of
the wires in the line cord was attached to the socket's screw-down
terminal. Then this went into the (overheat and loosen up and
concentrate the current into a smaller region) destructive feedback.
Also consider the supply current to the UPS might be non-linear. 10A
RMS might be 50A peak. Dissipation in the connector will probably go up
as the square of current. Peak heating may be part of the problem.
Karl Cunningham
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