Factorio Forums

Specifically when 'min consumption' or 'drain' is taken into account.

For example, assembler 2 is 150kw base, 5kw drain, 3 pollution. In game UI shows this as 155kw active, 3 pollution. Factory planner shows this as 155kw for 3.1 pollution. These differences show up with the expected differences with modules present.

So is an AM2 3 or 3.1 pollution when active?

Afaik, "drain" does not contribute to that entity's pollution (though if your power is delivered by boilers, then it will contribute to theirs).

Reading this : https://wiki.factorio.com/Pollution#Modules (and the section below) , neither drain nor consumption is mentioned, at least not directly.
Pollution seems to depend solely on base pollution (which is a flat value per minute), multiplied by energy consumption multiplier, multiplied by pollution multiplier when modules add either of those.