Even the layman can detect wether a relay is energized or not. The question how on the other hand, is difficult to answer even for the expert. What he needs to know is the timing of certain specific parameters such as pick-up delay, armature play, armature displacement, armature bounce, contact displacement, final contact position and contact bounce. These parameters can be derived from the measured armature and contact movement. The relay characteristics must not be affected in any way by the measuring equipment in the event. The noncontact displacement measuring systems optoNCDT offer the ideal solution to this problem.