Katkaisukyky

Katkaisukyky is a Finnish term that translates roughly to “cutting capacity” or “interrupting ability.” It is a general, domain-dependent concept used to describe how effectively a system, component, or material can sever or interrupt a connection, stream, or process. The meaning varies with context, but the core idea is the capacity to bring a current, force, or material flow to a halt.

In electrical engineering, katkaisukyky refers to the breaking or interrupting capacity of protective devices such as fuses and circuit breakers. It denotes the maximum current the device can safely interrupt without sustaining damage or creating unsafe conditions. This rating is typically given in kiloamperes (kA) and depends on system voltage and the expected fault current. Devices are specified to have a katkaisukyky above the highest prospective fault current in the installation, ensuring safe disconnection during faults. Standards from organizations such as IEC/EN define test methods and rating systems for these capacities.

In machining and materials engineering, katkaisukyky describes the ability of tools or materials to cut, shear, or sever a material. This includes factors such as edge sharpness, hardness, wear resistance, and tool life. Higher katkaisukyky implies more effective cutting performance and longer tool use before replacement or reconditioning is needed. The term can also appear in broader contexts to indicate the resilience of a component or system to abrupt termination of its operation.

Etymology-wise, the word combines katkaista (“to cut off” or “to break”) with -kyky (“ability”). See also related terms such as katkaisija (breaker) and katkaisu (disconnection).