The function of the fuse is to automatically fuse when the loop current is too large and the temperature is too high, thereby protecting the circuit and the load. After performing short-circuit test and data analysis, we will find that some loop test data cannot meet the design requirements. At this time, the loop needs to be rectified and optimized. The Wire Harness Manufacturer introduces several common problems and related optimization schemes in the short circuit test.
1. The fuse capacity is too large
Generally speaking, the fuse capacity is selected according to the load characteristics of the circuit. Therefore, we can change the fuse capacity according to the load characteristics. This method is not only simple and easy to implement, but also effective.
For example, from the test on the actual vehicle, the maximum working current of a certain load is 12A. In fact, we chose the 30A specification, the choice is too large, so the fuse can be selected 20A specification.
One more sentence here, when optimizing the fuse and increasing the capacity of the fuse, you need to pay special attention to the matching of the wire and the fuse. Be sure to ensure that the fusing current of the fuse is below the smoke value of the wire.
2. The fuse blowing time is too long
When designing the entire Automotive Wire Harness, sometimes the choice of wire diameter is based on the requirements of the load characteristics, but although some wires meet the requirements of the load, there are hidden safety hazards for the circuit system, so optimization is needed at this time. (One more mouth, choose the fuse first, then the wire)
High Quality Wire Harness For circuits with too long fusing time, the optimization method is to thicken the loop wire diameter, thereby reducing the loop resistance, increasing the loop short-circuit current, and shortening the breaking time.
3. Unreasonable selection of fuse type
The main function of the fast-acting fuse (MINI) is to prevent short circuits, while the main function of the slow-acting fuse (JCASE) is to prevent long-term overload of the circuit. In the case of a short circuit, whether it is a fast-blow fuse or a slow-blow fuse, it should be blown.
In the process of short circuit test, we can simulate the current characteristic curve of the load through an oscilloscope, and we will find that the motor load uses fast-blow fuse, or the resistance load uses slow-blow fuse. In this case, it may cause fuse If it cannot be blown normally, you need to change the type of the fuse.
Automotive Wire Harness
4. The total length of the loop is too long and the test fails
When the wire loop is too long, the resistance will increase, causing the fuse to fail to protect the wire. At this time, we can increase the wire diameter, but sometimes due to the influence of terminal crimping, it may need to be optimized by changing the length of the wire.
Generally speaking, it is not recommended to use the method of changing the total length of the loop to optimize the short-circuit performance, because changing the length of the loop may change the layout of the load or change the connection method of the loop in principle, and also consider the connection with other loads after the change. Matching and other issues, but this solution is also feasible. Commonly, the length of the whole loop can be changed by changing the position of the grounding point according to the schematic diagram of the whole vehicle circuit system.