Magnetic Contactor Basics: Structure and Working Principle

Now we shall consider the magnetic contactors used in practical applications.
Electric switches operating on the magnetic principle for enabling low voltage signals to conduct the high voltage circuit are termed a magnetic contactor. These are used extensively for both black and white applications in industries, a consideration of which makes it necessary to carry out such tasks as distribution of power and controlling the motors. Let us have an idea of the contactor structure and the principle of working related to it, and essential for selecting the designed pieces of equipment for our Electrical Systems.
What is a Magnetic Contactor?
A magnetic contactor is as stated earlier, a kind of heavy duty relay intended to de-energize or energize electrical loads on command. The electromagnetic coil in it produces a magnetic field which attracts a movable contact arm, and moves it to a position whereby it closes (or opens) the contacts used to control the circuit for powering the electrical circuit through the magnetic contactor. Such apparatus is widely used in industry for switching electrical circuits for use in air conditioners, heating apparatus, machinery, and other large scale electrical applications. Let us study the structure of a magnetic contactor and try to figure out the details properly.An electromagnetic magnetic contactor is comprised of, obviously, an electromagnetic coil which serves to produce a magnetic field whenever current is permitted to flow through it; of an armature, which is that ‘floating’ part that gets attracted by the magnetic field, and thus moves the contacts either in the opened or closed position; and of the contacts.
Magnetic contactors, come in pairs, so that they may answer for themselves a LA (is a set of appropriately-changing contacts) when either of them is turned ‘on’ and closes the other. These, are usually referred to as “normally-closed” (NC, having completed) and “normally-open” (NO having prevented), Maybe in a RSV conceptual form, perhaps, magnetic contactors desirable type.The main elements in this circuit might include the following:Coil: An electromagnetic coil inside the contactor.Contacts: The actual touch points that the coil operates to open and close flow through the wires and connections.Frame: A housing that keeps the other components together and provides insulation.Spring: A spring loading that keeps the contacts in default position when magnetic field is nonexistent.Auxiliary Contacts: Additional contacts which serves to feedback or control other circuits.
How Does It Work Then?It becomes apparent how a magnetic contactor does its job.The working principle is to build up an electromagnetism strong enough to move the contactor when a current passes to the coil in that direction. Here’s how.
Energizing the Coil – sending a current (control signal, usually of low voltage) through the coil sets up a magnetic field.
Magnetic attraction – the magnetic field then attracts the armature, which therefore moves, opening or closing the contacts, according to their immediate overall design.
Closing of the Circuit – if the contacts are normally-open, they have closed and current is flowing through the circuit from its energized load.
De-energizing the Coil – taking away the control current from the coil collapses the magnetic field. The spring pulls the armature back, re-opening (if closed) and breaking the circuit.
Types of Magnetic Contactors
Besides the general beloved magnetic types we talked about, there are types especially made for AC motors and other loads, whether in AC or in DC (the latter very desirable for battery driving and for solar power system, etc.); and a molded case type in use in manufacturing plants, which is just a touch too expensive for general use.
Applications of Magnetic Contactors
With magnetic contactors installed and controlling motors made up according to AC and DC voltages, they are most frequently used, and fewer and fewer machines and plants are set into service without them, on the control of machines and attendant apparatus like alarm or guard circuits, plant lighting systems, etc. Great accuracy is obtainable in virtually instantaneous control of motor starting and stopping with this apparatus.
Advantage of Magnetic Contactors
Reliability, for under the most relentless curse of continuous toiling to do its master’s bidding in an industrial plant, there is no appreciable deterioration in the functioning contact Cum different parts of a plant or factory system. This means maximum energy used in control of electric currents; great purity of load in suitably designed load coils, switches, etc., and maximum safety from shock, automatic fault finding devices, etc. Such as over current protection, over heating and the like. Besides it is a available easy face to variety of control circuits sprung very productively, and makes settings for greater cascading effect of less soaking in the metal frame tresumes. This is classification of the magnetic-lead. Swinging seems to be worthy enough either side to rugged efforts to settle.