Electromagnetic contactor with current regulated electromagnetic coil for holding the contacts closed

Abstract From the Canadian patent

53,662, ABSTRACT OF THE DISCLOSURE, An electromagnetic contactor is taught which includes a conduction angle controlled triac or similar gated device which is connected in series circuit relationship with the winding of an electromagnetic solenoid or coil which is responsible for closing the contactor contacts and for keeping them closed. The current flowing through the triac is fed to a microprocessor which digitizes the current and compares it to a stored standard. The conduction angle is then decremented or incremented as necessary to change the conduction angle to cause less or more current to flow per half cycle until the amount of current flowing as sensed on a …