Emotron FDU 2.0 AC drive

4.5.5 Current signals ((0)4-20 mA)A current signal like (0)4-20 mA is less sensitive todisturbances than a 0-10 V signal, because it is connected toan input which has a lower impedance (250 ) than avoltage signal (20 k). It is therefore strongly advised to usecurrent control signals if the cables are longer than a fewmetres.4.6 Connecting optionsThe option cards are connected by the optional connectorsX4 or X5 on the control board see Fig. 30, page 23 andmounted above the control board. The inputs and outputsof the option cards are connected in the same way as othercontrol signals.4.5.6 Twisted cablesAnalogue and digital signals are less sensitive to interferenceif the cables carrying them are “twisted”. This is certainly tobe recommended if screening cannot be used. By twistingthe wires the exposed areas are minimised. This means thatin the current circuit for any possible High Frequency (HF)interference fields, no voltage can be induced. For a PLC itis therefore important that the return wire remains inproximity to the signal wire. It is important that the pair ofwires is fully twisted over 360°.28 Control Connections Emotron AB 01-4428-01r3