A device, by the fusing of one or more of its specially designed and proportioned components, opens the circuit in which it is inserted by breaking the current when this exceeds a given value for a sufficient time.
A fuse which opens on overload and short circuits very quickly. This type of fuse is not designed to withstand temporary overload currents associated with some electrical load. UL listed or recognized fast acting fuses would typically open within 5 s when subjected to 200% to 250% of its rated current. IEC has two categories of fast acting fuses:
● F = Fast acting, opens on 10 times rated current within 0.001 s to 0.01 s.
● FF = Very fast acting,opens on 10 times rated current within less than 0.001 s.
A fuse with a built-in delay that allows temporary and harmless inrush currents to pass without operating. In design, the breaking time under the condition of continuous overload and short-circuit current shall be: UL listed or recognized time delay fuses typically open in 2 minutes Max. when subjected to 200% to 250% of rated current. IEC has two categories of time delay fuses:
● T = Time-Lag, openson 10 timesratedcurrentwithin0.01sto0.3 s.
● TT = LongTime-Lag, openson 10 timesratedcurrentwithin0. 1 s to 1 s.
The rated current of a fuse identifies its current-carrying capacity based on a controllable set of test conditions. Each fuse is marked with its rated current, this rating can be identified with a numeric, alpha, or color code mark.
A Max. open circuit voltage in which a fuse can be used, yet safely interrupt an overcurrent. Exceeding the voltage rating of a fuse impairs its ability to clear an overload or short circuit safely.
Root Mean Square Current
The R.M.S. (root mean square) value of any periodic current is equal to the value of the direct current, which flowing through a resistance, produces the same heating effect in the resistance as the periodic current does.
Normal Operating Current
The normal operating current of a circuit is the level of current drawn (in RMS or dc amperes) after it has been energized and is operating under normal conditions. An operating current of 80% or less of rated current is recommended for operation at 25 °C to avoid nuisance openings. For example, a fuse with a Rated Current of 1 A is usually not recommended in circuits with normal operating currents of more than 800 mA. Further derating is required at elevated ambient Temp..
The melting, arcing, or clearing integral of a fuse, termed I2t, is the thermal energy required to melt, arc, or clear a specific current. It can be expressed as melting I2t, arcing I2t or the sum of them, clearing I2t.
Can be classified as an overcurrent which exceeds the normal full load current of a circuit by 2 to 5 times its magnitude and stays within the normal current path.
A condition which exists in an electrical circuit when the normal load current is exceeded. Overcurrent take on two separate characteristics-overloads and short circuits.
An overcurrent that leaves the normal current path and greatly exceeds the normal full load current of the circuit by a factor of tens, hundreds, or thousands times.
The amount of time from the instant the fuse link has melted until the overcurrent is interrupted, or cleared.
The total time between the beginning of the overcurrent and the final opening of the circuit at rated voltage by an overcurrent protective device. Clearing time is the total of the melting time and the arcing time.
Breaking Capacity Of A Fuse-link
Value(r.m.s.forAC)of prospective current that a fuse-link is capable of breaking at a stated voltage under prescribed conditions of use and behaviour.
● Power Supply
● General Lighting
● Smart Home
● Office Equipment
● Electric Tool
● Medical Equipmen
● BS Plug
● BS Socket
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