Surge protection general question

[westom]

I have highlighted a couple of passages that seem to indicate that AC output modules only require surge suppression if the solid state output module switch is in series or parallel with a "hard contact" such as a push button or selector switch.

Solid state means no spike is created by disconnecting. Same is not true of a mechanical switch. Timing (how semiconductors go open circuit) is critical to understanding why semiconductors do not need suppression and why other 'crude' switching devices (ie a switch) may make it necessary.

This might be obvious by viewing with an oscilloscope.

 

[Albert LaFrance]

Automation Direct has an application note on the topic:
http://support.automationdirect.com/docs/an-misc-032.pdf

 

[deanfran]

Someday I will convince the boss we need an oscilloscope. Albert thanks for that resource.

 

[westom]

Learn how a thyristor works and therefore why that suppression obviously is unnecessary.