Fuses, also known as fuses, play a role in the circuit to protect the safety of the circuit. Commonly used fuse specifications (lead not less than 98%, antimony 0.3~1.5%, impurities not more than 1.5%) Diameter (mm) Rated current (A) Rated power (W) Fusing current (A) Fusing power (W), mainly rated current, rated power and fusing power.

The main parameters of fuse selection.

1.Voltage rating

The voltage rating of the fuse must be greater than or equal to the maximum voltage that will break the circuit. Due to the very low resistance of the fuse, the voltage rating of the fuse only becomes important when the fuse attempts to blow. When the fuse element melts, the fuse must be able to open quickly enough to extinguish the arc and prevent the open circuit voltage from re-triggering the arc through the disconnected fuse element.

2.Current Ratings.

Current ratings indicate the current carrying capacity of a fuse under a set of test conditions. Each fuse is marked with a current rating, which may be numeric, alphabetic, or color coded. The significance of each marking can be found on the product data sheet.

3.BreakingCapacity/lnterruptingRating.

A fuse must be able to break a faulty circuit without damaging the surrounding circuit. Breaking capacity is the rated voltage, the fuse can safely break the circuit, and does not break the maximum current value. The breaking capacity of the fuse must be equal to or greater than the maximum fault current that can occur in the circuit.

4.Melting Integral.

Melting Integral of the fuse, is the energy required to fuse the fuse element of this fuse, also known as the melting value of l2t, the structure of the fuse element, materials and cross-loaded area determines the value of this value, each series of fuses according to the rated current value of the different materials and components used in different configurations, so to determine the I2t of each fuse is very necessary. Usually in DC circuits, 10 times the rated current is used as the fault current, so that the fuse breaks in a very short time, and a very accurate l2t is measured by means of a high-speed oscilloscope and an integration program.

5.Ambient Temperature.

Ambient temperature is the temperature of the air directly surrounding the fuse, not room temperature. The electrical characteristics of the fuse are rated at 25°C ambient temperature. Fuses are rated at an ambient temperature of 25°C. Either above or below this thermal temperature will affect the fuse’s breaking time and current carrying characteristics.