DJYVP computer cable structure: conductor with bare copper wire, insulated high-pressure polyethylene, twisted pair of two-wire and three-wire group, copper wire braided shielded cable. This product is used in computer-centric industrial automation control system for data and signal transmission, including communication, remote control, pressure and flow measurement, light connection, etc., the work site and control instruments connected to complete the instructions, records, , Alarm and other functions. Is the computer control cable, electric and distributed instrumentation signal cable upgrade products. The computer's AC power cord to be a good shield, and seriously terminate the shielding layer, the high permeability material can be spiral wound in the outer layer of the cable and then add a layer of plastic sheath as a protective layer. This shielding effect is better, but it also with the cable terminal impedance, the characteristic impedance of the incident signal and the direction of the incident signal and other factors, because the terminal impedance and characteristic impedance on the cable may exist in the standing wave has an impact.
In addition, the relative length of the cable has an effect on the sensing level across the cable shield relative to the wavelength of the external electromagnetic wave. The performance of the connector used and the degree of bending of the cable, but also affect the cable shielding effect of the important factors. When the cable is bent into a corner, the coverage near the inner half is the largest, and the coverage on the outer radius side is significantly reduced.
For the end of the shield of the cable, in general, all other parts of the shield shall be insulated from the ground except for the specified ground, for the purpose of preventing unwanted grounding, since the shield is connected to the enclosure or base Any accidental contact can produce a small arc discharge there, forming noise that affects the operation of the circuit, and the shield can not be used as a loop conductor for the signal.
Copper and aluminum as a cable shield is better, because it has a lot of reflection of electromagnetic waves. For cables with very high spectral components, a multi-point grounding method can be used to ground the shields at both ends of the cable at the same time. If applicable, add a connector to ground the shield in the middle.
For shielded audio-sensitive circuits can only be grounded at one end, to this type of cable shield must be insulated from ground to prevent unnecessary grounding.