[Piotrsko]

High amp long duration engage generally requires silicon switching, MOSFET, TRIAC or IGBT, your choice but generally PWM. some delay can be gained with discretes, but only for short duration because RLC time constants and resulting current are short for the available component capacity. They are already inductive and kinda need full voltage although I suspect the clutching action would partially function at lower volt inputs. What's it going to do: wear out the iron powder? Could abrade the clutch gap towards broken, however. Not my pay grade.