ELECTROMAGNETIC CONTACTOR WITH CONTROL CIRCUIT FOR PROVIDING ACCELERATION, COAST AND GRAB FUNCTIONS

摘要

An electromagnetic contactor or controller is taught in which the voltage which is impressed across the electromagnetic armature accelerating coil is compared by a microprocessor against a menu of memory stored voltages with related delay angles. The delay angles are utilized to alter the conduction interval of a triac or similar gated device which is connected in series circuit relationship with the coil in question. During an ACCELERATION interval a number of consecutive full-wave rectified half-cycles of voltage pulses (106) are phase angle or delay angle controlled so that the amount of energy provided to the moving armature of the contactor is approximately sufficient to cause the armature to abut a fixed magnetic member. Furthermore, there is provided a separate memory menu for mid-flight adjustment of the armature to compensate for unknown variations to fine tune the closing operation. This latter correction is known as COAST. There is also provided a GRAB function which supplies limited, relatively low level current to the armature at or near the time of abutment for preventing "bounce". Mechanically interconnected with the armature is a set of contacts which are caused to close upon an external circuit for providing a useful function in response to the movement of the armature. One field of use is in motor starters; an advantage lies in the fact that the present system is more reliable.