Multymeter.com-Electrical Engineering: In electrical installations, the contactor component is not a new item. In electrical panels, the contactor (Magentic Contactor) is often used. Contactors or Magnetic Contactors are electrical equipment that works by electromagnetic induction. In the contactor there is a winding or coil, if an electric current is applied, there will be a magnetic field in the iron core and the contacts will be attracted by the magnetic force. Auxiliary contact NO (Normally Open) will close and Auxiliary contact NC (Normally Close) will open.
The contacts on the contactor consist of main contacts and auxiliary contacts. The main contact is used for the power circuit while the Auxiliary contact is used for the control circuit. Important components contained in a contactor, among others:
Magnetic coil (coil) with symbols A1 – A2
The main contacts consist of numeric symbols: 1,2,3,4,5, and 6.
Auxiliary contacts usually consist of the numeric symbols 11,12,13,14, or the numbers 21,22,23,24 and also the leading numbers onwards but the last digits remain from 1 to 4.
There are 3 types of magnetic contactors that are often used:
Main magnetic contactor.
Auxiliary magnetic contactor.
Combination magnetic contactor.
Magnetic contactor specifications that must be considered are the power capability of the contactor written in Watt / KW, which is adjusted to the load carried, the ability to conduct current from the contacts, written in amperes, the voltage capability of the magnetic coil, whether for a voltage of 127 Volts or 220 Volts, as well as frequency, the ability to protect against low voltage, for example, written ± 20% of the working voltage. Thus, in terms of safety and practicality, the use of magnetic contactors is much better than ordinary switches. The advantages of using a magnetic contactor instead of a manually operated control device include:
In handling large currents or high voltages, it is difficult to build a suitable manual tool. Moreover, such a device is bulky and difficult to operate. In contrast, it would be relatively simple to construct a magnetic contactor that would handle large currents or high voltages, and manual tools would have to control only the coils of the contactor.
The contactors allow multiple operations to be carried out from a single operator (one location) and are interlocked to prevent errors and operating hazards.
Operations that must be repeated several times an hour, contactors can be used to save effort. The operator simply has to press a button and the contactor will start the correct sequence of events automatically.
Contactors can be controlled automatically by means of pilots or highly sensitive sensors.
The high voltage can be overcome by the contactor and distances it entirely from the operator, thereby increasing the safety / security of the installation.
By using contactors the control equipment can be attached to remote points. The only space required near the machine is room for the push button.
With contactors, automatic and semi-automatic control is possible with tools such as programmable logic controls such as the Programmable Logic Controller (PLC).***
