Kortslutningsvärden

Kortslutningsvärden, or short-circuit values, are crucial parameters in electrical engineering that describe the magnitude of current that would flow during a short circuit. A short circuit is an abnormal connection between two points in an electric circuit that have a difference in electrical potential. This connection typically has very low impedance, allowing a large current to flow.

The primary short-circuit values are the prospective short-circuit current and the making current. The prospective short-circuit current is the maximum RMS (root mean square) value of the alternating current that would flow if the circuit were short-circuited. This value is important for determining the interrupting capacity of protective devices like circuit breakers and fuses. The making current is the peak instantaneous current that occurs at the moment of the short circuit. This is important for assessing the mechanical forces that protective devices and other electrical equipment must withstand.

Short-circuit values are typically calculated for different locations within an electrical network. These calculations consider the impedance of the power source, transformers, cables, and other components. The closer to the power source, the higher the short-circuit current will generally be. Understanding these values is essential for ensuring the safety and reliability of electrical installations. Incorrectly rated protective devices can fail to operate during a short circuit, leading to equipment damage, fire, or injury. Conversely, oversizing protective devices can lead to unnecessary costs.