PLC and fusing

[matlark]

Just to make the numbers easy...if I have a ML1200 driving 10 amps (various small motors and solenoids) I would need to fuse the secondary side of the transformer at 12.5A? Used 125% since above 9A.

thanks

 

[iant]

not certain what knowledge you have.
you should have regulations for wiring equipment like this. - maybe not.
Understanding the load of a control circuit is very important
In a non PLC environment it is common practice, here, to calculate maximum demand. similar to the total number of devices that can be loaded at the same time.
This is slightly different, but, consider the types of motors/solenoids and their magnetising/starting currents.
you will need to take this into your calculations or you may suffer false tripping of circuit breakers. HRC fuses, not commonly used any more,need to carefully sized as well.

 

[matlark]

Neglecting the fact I may need fusing on each output, diodes, etc... would fusing the secondary at 12.5A be sufficient.

 

[matlark]

nvm I got it.

thanks

 

[iant]

I would definately not use the PLC output to directly switch a 10 Amp load.
3 Amp resistive only

 

[matlark]

Each plc output can output a max of 2.5A, so a small motor, solenoid, etc should be fine, but getting off topic.

 

[Tom Jenkins]

When fusing motors and solenoids you may want to look at slow-blow fuses to accommodate the inrush. I've found that saves some nuiscance fuse blowing.

 

[shooter]

that is for short circuit correct, however the outputs are not safe unless you fus wit2.5 amps. (is 5 amps max)