Shielding in Instrumentation Cables

Shielding in Instrumentation Cables is vital in order to prevent stray coupling from other circuits nearby. 

When an instrumentation cables is laid beside a power cable, there are chances of  electromagnetic coupling taking place which can induce voltages in the instrumentation cable.  This can distort the signal in the instrumentation cable.  To prevent this, instrumentation cables are provided with a shield, usually made of aluminium.  

This shield magnetically shields the wires inside it.  This eliminates the chances of stray coupling.  The shielding needs to be grounded at one end.  Grounding the shield at two ends will cause grounding loops which can cause interference.