External fuse and Functional Safety considerations

External fuse

Modules and installation have to be protected by an external fuse.

The power bar can internally link supply power from module to module.

The maximum load on the power rail is 10A; therefore the maximum external fuse in the supply wire should not exceed 10A.

The power supply to a block of modules can be divided into as many groups as required.

Because the 24V DC side of the power supply is connected to ground, the fuses have to be applied to the 0V DC wires.

Failsafe installation according to Functional Safety Regulations

The power supply has to be connected to ground, to avoid any free-floating potential on the 24V side.

To make the installation safe according to Functional Safety Regulations, the positive side of the 24V DC supply has to be connected to ground. This ensures that no current can flow in the ground connections in the event of a cable or installation error, which could lead to devices being activated without the output being switched ON.