SHORT-CIRCUIT PROTECTION ACTION CURRENT REGULATING METHOD AND DEVICE THEREOF FOR MULTIPOLAR ELECTROMAGNETIC TRIP.

摘要

A Short-circuit protection action current regulating method and device thereof for a multipolar electromagnetic trip. The electromagnetic system comprises an auxiliary static iron core, a second static iron core, a coil, a reset spring and a movable iron core. At an initial position, a first gap is arranged between the auxiliary static iron core and the movable iron core, and a second gap is arranged between the movable iron core and the second static iron core. The thickness of the second gap changes in the same direction with size changes of a trip threshold value, and the elasticity of the reset spring changes in the reverse direction with size changes of the trip threshold value. When a trip current value is regulated from big to small, the energy of the coil decreases with the current flowing through the coil in a quadratic relationship. Meanwhile, the electromagnetic attractive force between the movable iron core and the second static iron core increases inversely proportional to the decrease of the thickness of the second gap in a quadratic relationship. Through the automatic balance between the two quadratic functions, regulation of the trip current value and the electromagnetic attractive force needed when the movable iron core acts have a fixed linear corresponding relationship. Regulation of the trip threshold by users is convenient, reliable and stable.