PMAC Product Guide Shielded Cable In general, it is good practice to shield all wires carrying low-level signals. This is important especially if the signal level wires are run near power level wiring such as motor wires or relays wires. When shielding wires connect only one end of the shield, preferably the source end. Connecting both ends of a shield will result in ground loops. It is recommended that the unconnected end of the shield be insulated to prevent accidental connection. Wires Separation and Length Since the electromagnetic interference drastically decreases with distance, the best method to prevent EMI is to separate the power cables from the signal cables.
In addition, since the capacitance and inductive characteristics of a cable increases with the distance, delicate signal cables must be kept short. PMAC’s JMACH cable should not exceed the 36 inches in length whereas PMAC’s JEXP cable should not exceed the 6 inches in length. Flat Cable Shielding When using shielded flat cables, select a rounded cable with IDC connectors in both sides. With the addition of ground bars this configuration makes a good reliable shielded connection. Wiring Guidelines 25