As we get closer to Spring and further into our Spring Blog Series, InterConnect Wiring would like to highlight the big question from one of our top blogs in 2019: what is a cable shield termination?
In the commercial aerospace and defense industry, we find a high concentration of electrical wiring in a relatively small area. The overall goal is to design the equipment and components as small as practical and locate the equipment in a compact, easily accessible area. This includes all wiring harnesses, cable assemblies, and aircraft relay panels. A small space like this is not conducive to minimizing electromagnetic interference (EMI); therefore, to combat the effects of EMI, a metallic shield is placed around the electrical conductors in wire then coated with insulation, such as TKT.
So, to answer the question, “What is a cable shield termination?” it is where a shield (obviously of a shielded wire) is terminated to another component. There is a wide variety of termination methods including:
1) Attaching a solder sleeve and jumper wire to the shield then the jumper wire is connected to the connector’s backshell.
2) Attaching a solder sleeve and jumper wire to the shield then routing the jumper wire to a contact cavity in a connector.
3) Attaching a solder sleeve and jumper wire to the shield and the jumper wire is “daisy-chained” to the jumper wire of other shields.
4) Placing a piece of shrink tubing over a shield and it is floated (not connected) to any conductor or ground point.
The purpose of a shield in a shielded wire is to eliminate EMI that is caused by the electrical current in the conductor of a wire. Likewise, a shield limits EMI caused by other nearby wires. Shields eliminate crosstalk between wires so you have a clear signal. The most common practice in the aerospace industry is to terminate the shields to a jumper wire then the jumper wire is connected to a ground point. In many cases, the ground point is the backshell of a connector which ultimately connects to the airframe.
Contact Us if you would like more information about how to terminate a shield.