A magnetic starter, also known as a contactor, is an electrical switch used to start high-current equipment like electric motors. It relies on an electromagnetic field to close contacts that transfer power to the motor. Magnetic starters have main contact points, auxiliary contacts, and thermal overload protection devices. They allow remote starting and offer overload protection. The starter consists of two rolled steel cores and sets of contact points that act as a switch to control the electrical power to the motor. The circuit which supplies current to the coil is known as the control circuit.
A magnetic starter is an electrical switching device commonly used as a starting mechanism for electric motors and other high-current equipment. Also known as a contactor, the magnetic starter relies on an electromagnetic field to close a series of contacts which then transfer power to the motor. This electromagnetic field is provided by a two-piece rolled steel core and coil of wire connected to the starter’s control circuit. When the starter button is pressed and the coil energises, it creates the magnetic field which closes the contact mechanism and starts the engine. Magnetic starters can have two to four sets of main contact points and often have built-in sets of auxiliary contacts and thermal overload protection devices.
Most electric motor installations and heavy equipment use a magnetic starter to initiate operation. Often called contactors or relays, magnetic starters allow remote starting of equipment and, depending on the specific design, also offer overload protection and auxiliary switching. The main contact points in a magnetic starter act as switches to make or break the main power circuit to the motor. In the case of smaller single-phase motors, only two contact points will be needed, one each for the live and neutral lines. Three-phase motors will naturally need three contacts, one for each phase.
These starters consist of two rolled steel cores and two sets of contact points that act as a switch to control the electrical power to the motor. A steel core and set of contacts are fixed to the magnetic starter body and do not move. The second core and contacts can move and are connected together under spring tension to keep them separate from static units. Surrounding the static core is a coil of wire which, when energized, creates an electromagnetic field that pushes the moving core against the static core. The moving contacts travel with the plunger and press firmly against the static contact points to complete the motor power circuit.
The circuit which supplies current to the coil is known as the control circuit and it passes through the stop and start buttons, thus allowing remote control of the engine. There are usually at least one or two sets of auxiliary contact points separate from the sets of main contacts included in magnetic starters. These are used as interlocks, stops and to switch remote lamps which indicate the operating status of the engine. Starters may also include thermal overload devices that remove power to the coil and stop the motor if there is an overload.
Protect your devices with Threat Protection by NordVPN
