Hello,

the value and the characteristic of the fuse is depending of different reasons

• how many relays switch on at the same time
• how many relays are maximum at the same time on
• how high is the inrush current of the relay coil
• can you split the power supply e.g for every/few DO-module separately

These are a few questions which need a answer before you can calculate/select the right fuse.

regards
CaOd

Hello,

I assume that you use the 6ES7322-1BL00-0AA0.

The maximum current for every group at  the module is 4 A.
You need maximum round 100 mA (8 coil x 9 mA)

I would suggest you the follow:

• split the power supply, supply every DO-module separately (4 groups =  4 Byte)
• use a fuse with maximum 4 A, characteristic A
• use as possible a electronic fuse, e.g. Siemens SEL 1200/1400 or Phoenix Contact with 4 or 8 channels

Maybe is this link helpful to select the right fuse

Fusing of the output circuit 24 V DC, selectivity

If you have more questions, don't hesitate to ask.

regards
CaOd