Selection Principles of Automotive Wiring Harness

A wiring harness is the body of a network of automotive circuits that connects and enables the electrical and electronic components of a car to function. With many circuits, the number of harness parts to choose from is large, and the matching of parts to each other is important for automotive safety. Read the article to learn more about this part.

1. Terminals

1.1 Female Terminals

Generally, male terminals are set at the equipment end, and the model is selected by the electrical performance of the equipment. The female terminal for docking with the equipment end is generally used in combination with the male terminal and does not need to be selected separately. And the selection of male and female terminals for harness docking, the first thing to know is the current value of the flow through the circuit.

Common width 0.64mm terminals allow the current value is generally less than 3A. The current value of the circuit is small, the general choice of 0.64mm terminals can be (Figure 2). The motor and other equipment operating current values are larger, and generally choose 0.64mm, 1.0mm, or more terminals. The allowable current value of the terminal is related to the number of pins, wire size, energizing time, temperature, etc., so you need to check the drawing of the terminal to choose.

1.2 Male Terminals

In addition to the device end, there are also male terminals in the butt section of the harness, and the details of the male terminal selection are the same as the female terminal.

2. Connector

After the basic selection of terminals, for the selection of connectors, it is necessary to consider whether the need for waterproof, the number of holes, etc. The number of holes will affect the current attenuation coefficient and plugging force, these need to be repeatedly verified in the actual selection.

3. The choice of fuse capacity

Fuse wire is to protect the equipment, its main role is to play overload protection. If the circuit is correctly placed in the fuse wire, the fuse wire will be abnormally high in the current to a certain height and heat, its own fuse cut off the current, to protect the safe operation of the circuit. Therefore, it is necessary to determine the capacity of the fuse by looking at the current flowing through the fuse from the downstream equipment. Considering the endurance characteristics of the fuse, as shown in Figure 3, the total rated current should be less than 70% of the fuse capacity as the initial selection condition. In addition to this, it is also necessary to consider whether there is a sudden incoming current, oscillation current, etc. Consider the endurance characteristics of the fuse according to the actual current condition.

4. Wires

Wire type

The wire type should consider whether it needs to be heat resistant, whether it needs special wire types such as twisted pair or shielded wire, whether it is used in curved parts, etc. After considering the above special requirements, select the appropriate material.

Wire color

Usually, the wire color is selected according to the product manual, and there are no special requirements. In terms of workability, avoid using the same wire diameter in the same plug with the color next to each other to prevent mis-insertion during operation or misidentification during maintenance.

5. Overall circuit selection principles

The above mentioned a lot of physical selection of the basic method. But in fact, the selection of the parts of the circuit is not in pieces, but the whole. In the power circuit, the presence of the fuse actually protects the whole circuit from problems, so the fuse must be the weakest in the circuit.

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