Load limit integral

Limit load integral (area in green) of a semiconductor component

The limit load integral , also known as the melting integral and value, i.e. “I-square t-value”, is a criterion for the pulse-shaped short-term overload capacity of various electrical or electronic components such as a semiconductor component or a fuse . In the case of a fuse, the pulse-like overload is deliberately used as a fuse function and the triggering characteristic of the fuse is described by the fuse integral. ${\displaystyle i^{2}t}$

Mathematically, the limit load integral for an electric current can be expressed over time as: ${\displaystyle i}$ ${\displaystyle t_{1}}$

${\displaystyle \int _{0}^{t_{1}}i^{2}\mathrm {d} t}$

In this integral the current is a function of time . ${\displaystyle i}$ ${\displaystyle t}$

Sensitive components are therefore protected by fast-reacting overcurrent protection devices ; the melting integral of the fuse has a lower value than the limiting load integral of the component to be protected. ${\displaystyle i^{2}t}$

The load limit integral does not provide any information on the load limit in the case of periodic impulse loads or continuous load by direct or alternating current. The maximum current value determined by the limit load integral is usually, the specific values ​​vary greatly depending on the component and application, by a few orders of magnitude above the permissible continuous current load. For the design of a component under a continuous current load or periodic current load, information going beyond the limit load integral is necessary.

literature

• Klaus Schon: Impulse voltage and impulse current measurement technology: Basics - measuring devices - measuring methods . Springer, 2010, ISBN 978-3-642-13116-5 , Chapter 6.1.7: Limit load integral.