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#86587 11/13/03 08:29 AM
Joined: Apr 2002
Posts: 178
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Can some explain the current fault conditions.I was explaining to a guy about inrush current on breaker being more than breaker set point for a short time period before it trips.I really don`t feel I`ve done a good job explaining it so I`m asking for some assistance.How does a breaker lets say 40 amp double pole square D home line work to protect agaist fault current.

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#86588 11/13/03 08:58 AM
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Most convebtional CB's have a thermal component which responds, (relatively slowly)
to lower level overloads in a manner which is inversely proportional (time v. current)to the overload.
There is also a magnetic component, which in the event of a ground-fault or short-circuit, will respond almost instantaneously to this, normally much higher level of overcurrent.

#86589 11/13/03 11:01 AM
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Another term for how breakers and fuses react to overcurrent is an inverse time-current characteristic. Simply—the higher the current, the faster the device operates.

Detail: www.usace.army.mil/publications/armytm/tm5-811-14/

Quickie: www.cbibreakers.com/magnetic.asp?menu=sixth


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