Remote control line b

When the relay and contactor control lines are very long (for example, AC 220V exceeds 200m), due to the influence of the voltage drop on the control line
and the distributed capacitance of the line, the relay and contactor may malfunction and lose control. Measures must be taken
to prevent this. There are many ways to prevent it, two of them are introduced below.
    The remote control circuit is shown in Figure 6-18. The critical length L of the control line to avoid malfunction of relays and contactors and out-of-control control can be
calculated according to the following formula:
    two-core cable L 1 pinch etc. × 103 (m)
    three-core cable L 1 pinch × 103 (m)
where PH -Rated holding power of relay or contactor, w;
    U. ——Rated voltage of relay or contactor coil, V.