All you should know about BS88 Fuse
What does the voltage drop of the fuse indicate?
The voltage drop of a fuse is the voltage drop across the fuse under rated current conditions. It reflects the internal resistance of the fuse, and its value should not be too large.
If a fuse with too large internal resistance (voltage drop) is installed in the circuit, it will affect the system parameters of the circuit and cause the circuit to not work properly.
The standard not only stipulates the upper limit of the voltage drop value but also stipulates its consistency. If you would like to know the resistance data of HIITIO fuses, please contact us.
What is the difference between Melting I2t, arcing I2t and Clearing I2t?
In the event of a short circuit, the fusible element begins to melt and then separates within milliseconds. The heat energy generated by a fuse during fault current breaking is usually expressed in joules, often called
A2s or I2t
It is proportional to the square of the current (‘I’ in amperes) during operation (‘t’ in seconds). The heat energy generated is expressed as melting I2t, arcing I2t and clearing I2t.
Melting I2t
This is the amount of heat energy that passes through the fuse after an overcurrent occurs until the fuse element melts. It is equal to the RMS current squared times the melting time.
Arcing I2t
This is the heat energy passing through the fuse during the arc discharge. It is equal to the root mean square arc discharge current squared times the arc discharge time.
Clearing I2t
Also known as total clearing I2t, this is the I2t flowing through the current device from the beginning of the overcurrent until the current is completely interrupted. Clearing I2t is the sum of melting I2t and arcing I2t.
How to use the fuse temperature derating curve?
The current carrying capacity of a fuse depends on the operating ambient temperature conditions of the application in which it is used. It decreases as the ambient temperature increases and vice versa. The temperature derating curve can be used to determine this change in the current carrying capacity of the fuse over the operating temperature range.
The temperature derating curve shows the widest ambient temperature range (X-axis) over which the fuse can operate safely (also called the operating temperature range), and the corresponding derating factor to be applied to the rated current of the fuse.
The following figure is an example, assuming that a 100A fuse is used and the ambient temperature is 60℃. It can be seen from the curve in the figure that the derating coefficient is 0.8 at 60℃. Therefore, an 80A fuse should be used in this case (100A * 0.8 = 80A)
What is the significance of paying attention to the temperature rise of the fuse?
The temperature rise of the fuse refers to the temperature rise value of the fuse when 1.1 times (110%) of the rated current flows through the fuse, that is, the measured temperature minus the ambient temperature. The UL standard sets the upper limit at 75℃.
Because the melt of the fuse is relatively sensitive to temperature, its fusing point and impedance will change under the action of a certain high temperature for a long time, and this change will affect the accuracy of the fuse. This is commonly referred to as fuse aging.
Aging fuses are very dangerous when used in circuits. Therefore, we should pay attention to the temperature rise of the fuse when designing and using fuses. In the same way, we should also note that even if the fuse has not blown after a long period of use, it may have aged, and it is best to replace it at this time.
