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====== 熔断器设计 ======

[[https://www.mechprod.com/blog/transient-currents-in-dc-and-single-phase-ac-inductive-circuits|直流和单相交流感应电路中的瞬态电流]]

<fs large><fc #4682b4>Transient Currents in DC and Single-Phase AC Inductive Circuits</fc></fs>

Our concern, here, is overcurrent protection, so we will restrict our attention to one particular location within a circuit, the location, or potential location of an interruptive device.  We arbitrarily divide the total circuit into two sections:   a delivery, or source, electrical network; and a load electrical network (Figure 2.1).  These two networks are connected by two current paths, one of which contains the interruptive device. 

Many of the principles outlined here are based on Mechanical Products’ published work, The Theory and Practice of Overcurrent Protection (1987).

If both the source network and the load network are linear – a common approximation which is entirely adequate for fault transient calculations – we can, by Thevenin’s theorem (2.1), replace each network by an equivalent source voltage, E, and equivalent network impedance, Z.  The equivalent source voltage for each network is the voltage which would be measured at the network terminals under open circuit (no load) conditions.  The equivalent network impedance is a mathematical description of the combination of resistances, capacitances and inductances that would be measured at the open circuit network terminals. 

This type of system modeling approach is foundational to circuit protection analysis and transient behavior evaluation (McCleer, 1987). 

The equivalent Thevenin networks for the source and load networks are shown in Figure 2.2.