Principle of dc electromagnetic relay time delay? How to set time delay?

Power dc electromagnetic relay time delay principle is the use of lenz's law, there are two ways: 1, damping copper set of law: when energized coil, the armature in the release position, air gap is big, the magnetic resistance is big, small magnetic flux, so the action of the damping copper sleeve is small, can not delay effect, and the coil power, due to the current moment is reduced, according to lenz's law damping copper will produce a set of induced current, hinder the change of the magnetic flux, maintain the armature is not immediately release, until the flux through damping set of copper consumption gradually make electromagnetic suction is not enough to overcome the reaction, the armature release, thus produce the power delay. 2, short coil method: when the electromagnetic coil power, immediately take the coil short, according to lenz's law the coil will generate a obstruct flux changes of the induced current, maintain the armature is not immediately release, power generating latency. Delay range adjustment: ( 1) Change release spring firmness: release spring tight, the bigger the release flux, the shorter the time delay. ( 2) Changing nonmagnetic spacer thickness: the shim thickness increases, increased latency. ( 3) To increase the power delay, time relay with damping sleeve is done but the combination of short coil method.