How a DC Magnetic Motor Controller Works

As manufacturing as well as industrial facilities evolved over the years, so have the ways we power the machinery. By power, I am talking about the controlling or initiating motion to perform a process. The key here is the industrial motors by themselves. Whether they're small, medium, or large, motors should be controlled. They need to be started, stopped, and varied in overall speed for security and also to properly perform their selected function. A motor rotating at unsafe rates can be hazardous to personnel and dangerous to the equipment to that they are connected. The motor controller comes into play to do just that. Control of this startup as well as the acceleration to a suitable speed, then the monitoring of the motor to ensure it's operating within its power rating, as well as course the stoppage of this motor.

For decades, a magnetic dc motor control was the most efficient way to get the job done. These sometimes complicated circuits composed of relays, vacuum contactors, timers, and resistors could be found anywhere there was an industrial electric motor. At the time, that they were new technologies replacing drum controllers which used the human element to control a motor's acceleration. on these controllers, an operator had the responsibility of turning on the motor and bringing it up to its proper speed using the handle attached to a drum of contacts. The faster the operator turned the handle, the faster the motor accelerated. Operating speed for the motor could also be controlled using the handle by stopping at a certain position short of full deflection. Motors might also be reversed using these types of controls by turning the handle in the opposite direction. Drum controllers relied too much on an operator's gentle touch to be efficient and safe. The dc magnetic operator easily became the accepted method of motor control in its time.

The operation principle of vacuum contactors

The controlled acceleration of a dc motor and its controlled top speed made these controllers ideal for industrial machinery.They all consisted of similar circuitry however various manufacturers had their own improvements and idiocyncrasies. The motor is usually started and stopped from a normally open as well as normally closed push button assembly. This controls a relay typically labeled CR, for control relay. The control circuit was always interfaced with overload as well as overtemp contacts for protection of the motor, the machinery, and human personnel. An M contactor indicates a main contactor. These dc vacuum contactors are designed with large current carrying contacts because they're responsible for applying and disconnecting the primary circuit for the armature. Once the control circuit is energized, the accelerating of the motor is initiated using a series of resistors and vacuum contactors. These vacuum contactors are typically labeled 1A, 2A, 3A, and so forth. Accelerating contacts are opened and closed dependent on the armature current draw in some controllers and by timers in others.