“Interrupt rating” is not the same as “ampere rating,” even though both these are dealing with current values.
When reading technical data about a particular fuse you will see symbols or rather abbreviations such as I.R. or IR which refer to “interrupt rating.” Other abbreviations could be A I.R., A IR, or kA I.R. which is “amperes interrupt rating” or “kilo amperes interrupt rating” respectively.
Given a particular rated voltage, this current rating refers to the maximum amount of instantaneous current that can be interrupted safely without explosion or damage to the fuse link carrier, such as the cartridge or tube. This interruption of current flow can occur in fault or short circuit conditions. This current rating has been approved through standardized tests.
Interrupt rating is also referred to as “breaking capacity.”