The active cable joints of the preventive safety system are located every 250 meters on the cable loop and along the entire length of the pipeline. These cable joints contain electronics and each have a unique id code. The electronics transmit their ID codes to the field controller as soon as they receive power. After identifying themselves, the joints automatically turn an internal switch allowing the activation current to move to the next active joint in the loop.

Operation

The insulated cables (DW 131 S) within the preventive safety marker band (DW 135 S) are linked together with active electronic joint units every 250 meters along the pipeline. The DW 137 S elements together with the field controller are capable of detecting errors between two active elements.

The DW 4377 S field controller provides the line with 15 V DC current. The first DW 137 S active joint unit the input voltage effect consumption 1mA which increases to 10 mA when transmitting its unique ID code. The code is sent to the DW 4377 S field controller. After sending the code, the active unit turns an internal switch allowing the activation current to move to the next DW 137 S active joint in the loop, which repeats the process. When the second active joint transmits its ID code, the first one goes into sleep mode. When in sleep mode, the active joint unit imposes a minimal burden of 160 µA on the line.

The active units are protected from energy surges. The DW 137 S is a plastic cylinder filled with resin. The resin protects the electronics within the tube from moisture and increases the hardness of the tube.

The Cables extend from each end of the active joint units. A loop can contain up to 100 DW 137 S active joint units without experiencing signal deterioration.