Analysis of a D-C electromagnet with cutout switch

THE force developed by a d-c electromagnet decreases rapidly as the gap is increased. To provide sufficient excitation to develop the force required at open gap and yet not overheat the coil, 2-section coils are used. A normally closed cutout switch is used either to insert the holding coil in series with the pickup coil, or to disconnect the pickup coil if the two sections are connected in parallel in the circuit.