Magnetic contactors are used principally for switching large motors on and off, especially in industrial situations where the reliable management of great numbers of motors is important and where connected apparatus must be kept quite outside danger. The contactor is the method whereby the electrical circuit of a motor is turned on or off. It is the principal means of controlling a large motor on either of its sides. Better Control. They are especially to be preferred where exact control is to be exercised; they make use of the electro-magnet and close the movable set of contacts on the motor circuit as the even closing. All parts of the mechanism being metal, wear is very slight, and the life of a contactor is naturally longer than that of a mechanical switch. Apart from the control of the current carried by the motor, the contactor definitely protects both motor and circuit against either of them suffering disablement against electrical short circuit, excessive temperature, or overload by too great a current. The motor may then not be permitted to burn out, nor may the circuit run the risk of the expensive repair of the motor. An idle plant cut off by current is always a grave inconvenience. Less Friction. Economy is also a very important consideration in the management of our industrial motors. Large motors are cut in and out through the contactor without waste of energy and with little friction in the moving parts.The electromagnet serves to pull the movable contacts together and precludes jarring as in the mechanical switches. And this lessened friction contributes also to the total energy saving, making the magnetic contactor the economical choice for large motor operation.
Another energy saving feature of the magnetic contactors is their use in automated equipment. Such automated systems can be computer programmed to turn the motors on at the proper time of day and turn them off again when the desired use of the motor has been accomplished. Such automatically controlled operation avoids wasteful power usage and ensures that motors are operating only when they are needed.
Versatility and adaptability. Magnetic contactors are produced that can be used in practically any industrial application. They are built for different voltages, for different currents, and thus may be used on a motley of motor classes from low voltage to high voltage. Because of this adaptability, the magnetic contactors are ideally suited for such different industries as manufacturing, the mining industry, heavy machinery manufacturers, and the like where a variety of sizes and types of motors are in use. The magnetic contactors also have the advantage of being usable on both AC and DC motors, thus providing a universal contactor usable on a number of different motor systems and reducing the necessity of different kinds of switching devices.Availability of a number of safety features that may be built into the magnetic contactor makes such a contactor a welcome addition in the plant from the theoretical point of view.
Fearful arcing from build-up current is reduced when the contantor is rated to take the high inrush currents that may occur when motors are first started. Also, some magnetic contactors go a step further, so to speak, with built-in isolation features and present no electrical contact danger when they are open; consequently they are much safer to work with during maintenance or inspection.
- Reduced Maintenance Requirements
We have mentioned maintenance costs as a major consideration in an industrial environment, especially working with large motors that operate around the clock. Magnetic contactors require relatively little maintenance when compared to other types of switches, and especially to manual or electromechanical. This is due to the sealed construction, and the use of materials that are much more durable under the high stresses they must endure in operation. Finally, since there are no moving parts exposed to friction, there are relatively few parts than can wear out and the effect is less time-carrying maintenance and lower costs from the standpoint of the long haul. It may sometimes mean the difference between stop and go, and an on-line truck-loading at an oil refinery. - Cost-Effectiveness
As with anything else, we aren’t talking about peanuts. They will usually have a higher first cost than just any other switch we might have chosen. But we offset that in long term reliable service and low maintenance cost. Controlling and “managing” the big motors and drives, conserving energy, and providing better motor protection all far out-weigh the first costs in time. The longer life of the contactor means fewer replacement contactors and a lower over-all cost for the industrial user.
Conclusion
Where we have speed the heart of the industrial user’s controlling check on those ominously heavy-moving parts, we have also a controlling heart beating fast from its successful exertions and straining to keep up with the speed demand.
The beat is not hurried, because it is in right-ventricle-good-shape. Those industrial contactors are doing a good job.
How healthy, how successful a performance, the heavy inrushes, start-stop control of starting and stopping these great horses, protecting and controlling motors and drives in operation, with all the benefits of long haul lock-in service, the magnetic type contactor guarantees.
It is a sound choice, and its good for the whole industry. You might have thought only of improving your existing dire trouble monitoring, or of which to use in your large motor installation. In either case the magnetic has the performance you were looking for.
