Contactors and magnetic starters: features and differences

Magnetic starters and contactors are electromagnetic products, which are important elements of the electrical network. Each of them has specific functions and features.

The contactor is an electrical apparatus that is used for opening and closing the power circuits. The described processes are activated by means of electromagnetic forces. Currently, there are many different options for this device, which made it possible to create a clear classification. Depending on the type of current flowing in the circuit, where the contactor is installed, distinguish between DC and AC devices. At the same time, the former can be either single-pole or bipolar, while the latter are currently available in three- or four-pole versions. The contactor is controlled remotely and has the following operating principle: the coil receives voltage, because of the action of electromagnetic forces, the armature is attracted to the core, so that the contact group is set in motion. There is a break or a commutation of the circuit.

In turn, the magnetic starter is a small-sized contactor of a special design, which is most often used to start and stop induction motors with a squirrel-cage rotor, as well as to reverse them. In addition, this electrical apparatus can be additionally equipped with a thermal relay that will protect the circuit from overloads. The principle of the magnetic starter is as follows: when an AC current is applied to the coil, a magnetic discharge is created, which is closed through the movable and fixed cores, and also the air gap between them. When this happens, the previously named metal elements are attracted to each other and close both power and auxiliary contacts.

Contactors and magnetic starters are similar devices, but each of them has its own characteristics and differences.

The first is visual. The contactor housing has much larger dimensions, as well as a significant weight. A magnetic starter, in turn, is a small enough device that can easily fit in the palm of your hand.

The second difference is constructive. Contactors and magnetic starters have power contacts. However, the former do not have a body, but only arc chambers that cover the power contacts. Consequently, they are more susceptible to the destructive effects of the environment. It is recommended to install the contactor in special rooms that can protect this important element of the electric network not only from atmospheric precipitation, but also from unauthorized persons. The magnetic starter, on the contrary, is covered by a plastic casing, but does not have a bulky arc chute.

The third difference, characterized by contactors and magnetic starters, is the assignment of these electrical devices. As already mentioned earlier, the starters are designed for the operation of motors and other equipment, while the contactors carry out switching of power circuits.

From all of the above, we can draw the following conclusion: contactors and magnetic starters are important devices that not only simplify our life, but make it safe and comfortable.