Terms

Definition

Rate/working current

Current rating is the normal operating current of the fuse. The maximum continuous operating current of the circuit and the influence of the ambient temperature (Normally is 25 C) are important considerations when specifying the current rate.

Maximum current

It is related to the inrush current for various circuits, when we select a correct fuse, we need to consider this and choose “fast-acting” or “Time delay”product.

Voltage

The rated voltage is the maximum voltage at which a safe fault current interrupt occurs. The maximum effective operating voltage of the circuit is an important consideration when specifying the rated voltage. Also, consider AC or DC circuits. Higher voltages can be used in lower voltage circuits, but not vice versa.

I.R. or Breaking Capacity

The rated breaking capacity or interrupt rating is the short-circuit current at which the fuse can blow (at the rated voltage) without destruction or the maintenance or arcing or damage the fuse case. The maximum possible fault current is an important consideration when specifying a rated breaking capacity.

Size or Type

Depends on the requirements, normally it has SMD, Cartridge, radial leaded or various size in high voltage fuses.

Short circuit

Over 500% to 700% of rated – current applies to the fuse.

Overloading

Over 100% rated-current apply to the fuse.

Inrush current

Inrush current, input surge current, or switch-on surge is the maximal instantaneous input current drawn by an electrical device when first turned on.

TC curve

Time – Current Curve. The fuse curves represent the cutoff value of the prospective available short-circuits current under the given circuit.