What is the cut off current of the fuse

The "cut-off current" of a fuse is not a standard term in the context of fuse ratings or specifications. However, it may refer to the maximum current at which the fuse will open or "blow" to interrupt the circuit. This is often referred to as the "blow" or "trip" current.

When the current through a fuse exceeds its rated value, the fuse element heats up due to the power dissipation, eventually reaching a critical temperature where it melts or breaks, interrupting the circuit. This "blow" or "trip" current is typically slightly higher than the fuse's rated current to allow for short-duration overcurrent conditions without causing the fuse to open unnecessarily.

The "blow" or "trip" current of a fuse is closely related to its current rating and breaking capacity. The breaking capacity refers to the maximum fault current that the fuse can safely interrupt without causing damage or posing a safety hazard.

When selecting a fuse for a specific application, it's important to consider both the rated current and breaking capacity to ensure that the fuse can provide effective overcurrent protection while safely interrupting fault currents. Additionally, the operating conditions, environmental factors, and specific requirements of the application should also be taken into account to choose the appropriate fuse type and rating.