Advantages and disadvantages of three common shielding dealing of wire harness

2021-12-14

what is shielded wire :
The conductor wrapped outside the conductor is called shielded wire.

The conductor wrapped with conductor outside the conductor is called shielding wire, and the wrapped conductor is called shielding layer, which is generally braided copper mesh or copper (aluminum). The shielding layer needs to be grounded, and external interference signals can be introduced into the earth by this layer.

Function: prevent interference signal from entering the inner layer, conductor interference and reduce the loss of transmission signal at the same time.

Advantages and disadvantages of three common shielding dealing of wire harness:

1. use shielded wire alone

Method: each sensor and actuator uses shielded wire and is grounded independently

Features: the engine harness can effectively shield external interference and interference to the outside world, and the wires of the engine harness are directly independent of each other and will not infect each other;

Insufficient: each shielded wire needs to be grounded from ECU, and ECU module needs to support enough grounding points;

The shielding wire structure consists of insulating layer + shielding layer + signal conductor + shielding layer grounding conductor

2 .uses anti electromagnetic interference shielding braided tube.

Methods: depending on the existing braiding technology, metal braiding was used for harness branch and main circuit;

Features: strong reliability

The braided tube is one of the basic components of the semiconductor, which has the function of current amplification and is the core component of the electronic circuit. There are many types of crystal braided tubes in China, and the arrangement of pins is not the same. For braided mesh tubes with uncertain pin arrangement in use, it is necessary to measure to determine the correct position of each pin, or to find the transistor manual to clearly braid The characteristics of the network management and the corresponding technical parameters and information. The braided tube is woven with tough and environmentally friendly PET monofilament, which has strong stretchability, wear resistance, flame resistance and elasticity.
Reverse characteristic test: touch the red lead of the multimeter with the positive pole of the braided tube and the black lead with the negative pole of the braided tube. If the pointer is at or close to infinity, the pipe is qualified. For the positive characteristic test, touch the black lead (positive pole in the meter) of the multimeter with the positive pole of the braided network management, and the red lead (negative pole in the meter) with the negative pole of the braided tube. If the needle does not swing to 0 but stops in the middle of the dial, the resistance value at this time is the forward resistance of the braided tube. Generally, the smaller the forward resistance, the better. If the forward resistance is 0, it indicates that the die is short-circuit damaged. If the forward resistance is close to infinity, it indicates that the die is open circuit. Short circuit and open circuit pipes shall not be used.

Insufficient: large initial investment and low production efficiency; The sensors and actuators of the harness interfere with each other;

3.uses shielded Corrugated tube or tape

Methods: wrap shielding tape around the outside of the harness and then use bellows; Corrugated tube Or directly use shielded Corrugated tube;

Features: effectively shield RF interference;

Insufficient: the sensors and actuators of the harness interfere with each other; Large grounding impedance