Questions about output surge suppressors...

Seeing another post today reminded me of something I've had on my list for quite some time...

SLC-500 and MicroLogix user manuals have contained a section on output load spike suppression for over a decade, but it's the most commonly ignored installation recommendation.

Click to expand...

I'd have to agree with Ken's statement.... NONE of our plc's have any type of load spike suppression, with the exception of some of our Alvey Palletizers... They have them installed on the motor contactor coils, but nothing for the solenoids, or cube relays, or anything else....

So... How necessary are they?

What types of suppressors should be used(primarily 24vdc outputs, but some 120vac)? The manual says that for most 24vdc applications a diode is sufficient, but they have a recommended suppressor listed for starters, relays, etc.

Should they be part of a standard installation, along with fused outputs?

See pages 13, 14, & 15 in the attached tech note from Honeywell. They cover RC & MOV snubbers for AC and diodes for DC.

Dan

Hmmmmm.... It looks like THIS thread answered a lot of the same questions I'm asking in here... Gotta learn to read someday.....


But feel free to chime in with more responses. The more the merrier!