Plastic PC Lift Sensor
Plastic PC Lift Sensor In actual use, it is not enough to select the fuse according to the UL specification. 1. Several issues that must be considered when choosing Based on the parameters of the circuit used, the fuses are selected according to the following aspects: normal current, fuse...
Plastic PC Lift Sensor
In actual use, it is not enough to select the fuse according to the UL specification.
1. Several issues that must be considered when choosing
Based on the parameters of the circuit used, the fuses are selected according to the following aspects: normal current, fuse current (current and time that is desired to be blown), open circuit voltage, short circuit current, and inrush current (not cut off) Current, time and number of times), ambient temperature.
1 Normal current: First we must know the normal current flowing through the fuse in the circuit used. Usually we have to set a derating amount in advance, and then choose according to the following principle: the normal current must be less than the product of the rated current and the derating factor.
2 Fuse current: According to the UL specification, the fuse should be blown quickly at twice the rated current. However, in most cases, to ensure reliable fuses, we recommend that the fuse current should be greater than 2.5 times the rated current. In addition, if the fuse time is important, the judgment must be made by referring to the fuse characteristic diagram provided by the manufacturer.
3 open circuit voltage: open circuit voltage should generally be selected to be less than the rated voltage. For example, when a fuse with a rated voltage of 24VDC is used in an AC100V circuit, it is possible to ignite the fuse or break the fuse.
4 Short-circuit current: The maximum current value that we flow when short-circuiting the circuit is called the short-circuit current. For various fuses, the rated breaking capacity is specified. When choosing a fuse, we must take care not to make the short-circuit current exceed the rated breaking capacity. If a fuse with a small breaking capacity is selected, it is possible to break the fuse or cause a fire.
5 Inrush current: Observe the waveform of the inrush current (pulse current waveform) and calculate its energy by using the I2t value (Joule integral value). The magnitude and number of inrush currents are different and the effect on the fuse is different. The ratio of the I2t value of the inrush current to the fusing I2t value of the single pulse determines the number of times the fuse withstands the inrush current.
2. Other issues to be aware of
In actual use, the micro fuse has special requirements and problems for installation conditions, chemical resistance, ultrasonic cleaning performance, etc., and must be confirmed by the manufacturer in advance.
Micro fuses are different from ordinary electronic components such as chip resistors and chip capacitors. Due to differences in manufacturers, their specifications are quite different. In addition, the heat dissipation and wiring heat dissipation of the printed board will be brought about by the actual installation. The impact, therefore, the selection of the micro-fuse is correct, and ultimately should be identified by the state of the product.