Transistor outputs protection

[slav321 0]

Hi I am using DL PLC for some project,most of their transistor output modules have no short cuircit protection,my question is if i am using switching power supply say 1A for 16 outputs each 100mA and i have short cuircit on one of them will power supply react fast enough to save transistor or i should find better idea to protect outputs? Thanks.

[Armadillo852 25]

I would suggest using a fuse block for each output as well. I have had outputs burn out before because of a short circuit. Just like these.... Fuse Block Protection

[ianbuckley 0]

Having fuse blocks on output points where the wiring leaves the PLC enclosure is always a good idea, but it might not protect the output against a dead short in the field wiring. It depends on the junction rating of the output transistor, the series resistance in the output and the available short circuit current to the output point through the power supply - and how fast the power supply limits current. Whether it is worth doing anything more than standard fuse blocks is dependent on the application.

[paulengr 44]

Fuse them. It's cheap and easy to do. I like to use DIN rail fuse blocks with fuse blown indicators. Look at www.omega.com for DIN mount terminal blocks with fused through rails. That's about the most inexpensive source I've found lately that actually STOCKS the darned things. Most seem to be made in Europe (Wago, Weidmuller, Phoenix Contact, etc...even Allen Bradley charges 3X the going rate for something they are rebranding) and I can pretty consistently expect to have delivery problems no matter who the vendor is. The cost difference between fused terminal blocks and unfused ones is very little. You should be adding terminal blocks for connections outside the box anyways to facilitate replacing wiring whenever the inevitable happens.