Regarding Surge Protection

Hi dear All,

I would like to ask what is exactly means "Common & Differential mode input surge protection" with referance to AI Module. In AB PLC AI cards are come inbuid facility of surge protection is this right and is it not that much to use surge protection to any O/P module or card. cos i normally seen that all AI are used along with surge protection devices but not any O/P whether it is AO or DO why is it so?

In advance thanks for ur help.

http://www.maxim-ic.com/appnotes.cfm/appnote_number/2045/ this may help your understanding!

hi thanks for that site but on that site i got more information abt common mode inputs can i know more sites related to this topic. i need this regarding PLC input and Output cards.