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I'm not sure of the context , but the two who spring to mind are
- Simple circuits for demonstration ,
IE a basic generator like chemical element , thermocouple or photocell and a passive load
like a light or a coil .
-A circuit for flame proof rating
unlikely to be disturbed and which cannot store or change the energy profile of the supply
( no capacitance or inductance )
There could be other sense , why do you ask
?
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