What is shielded cable and why use it?

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Electrical equipment in industrial environments often emits electrical ‘noise’, usually radiated or conducted as electromagnetic interference (EMI). This interference can disrupt and degrade the quality of control signals and wireless equipment and cause inaccurate measurements, dropped signals and other undesirable effects.

What is shielded cable?

To protect signals from emitting or receiving electrical interference, shielded cable is often used. A shielded cable is an electrical cable which features an outside layer or ‘shield’ of conductive material around the internal conductors, which is connected to earth. The conductive shield can reflect or conduct external interference away without it affecting the signals in the internal conductors; or conversely, in the case of power cables, it can also prevent electrical interference from the internal conductors from escaping the cable.

When should I use shielded cable?

Shielded cable should be used where either a high level of electrical interference is expected to be emitted, e.g. on the power cables from a VSD to a motor; or where analog (e.g. 4-20mA) signals are being carried, which are more susceptible to external electrical interference.