Conductor Withstand Ratings
Conductor Withstand Ratings
(OP)
I have a situation where the conductors that I am trying to qualify have the possiblity of seeing locked rotor current for a maximum of 100 seconds. Does anyone know where to find short term withstand ratings for copper conductors?






RE: Conductor Withstand Ratings
RE: Conductor Withstand Ratings
One point often overlooked when determining long-time temperature exposure effects on cable, is that the connectors are more likely to be overstressed, than are the cables.
Another point of concern is the the increase in length of long cables.
RE: Conductor Withstand Ratings
RE: Conductor Withstand Ratings
RE: Conductor Withstand Ratings
An excellent treatise on the subject was presented in the April '79 issue of EC&M (Electrical Construction & Maintenance) magazine. It was presented by Dr. K.D. Srivastava of University of Waterloo, in Canada.
Four graphs show that a straight-line relationship between time and current, plotted on a log-log scale, also can be found for short-time overload... defined as being from 10 to 1,000 seconds.
Thus, if you have access to the typical Short-Circuit stress curves, then, by extending the time axis, you can determine the over-load thermal capability line for the cable & current condition you are concerned about.
RE: Conductor Withstand Ratings
A rather complex temp-rise formula is also presented.
RE: Conductor Withstand Ratings
Since the emergency overload is "long duration", this may be what you seek.