What Is a Contactor and How Does It Work?

What Is A Contactor?
In most industrial electrical systems, a contactor will perform the control functions. Often confused with relays, they are built for heavy-duty applications. When learning what a contactor is, think of electrical protection and control of the system. A contactor is electrical switch that switches electrical circuits on and off electronically. Best directed towards high-power applications, you’ll find a contactor in industrial equipment and machinery, heating and cooling systems, motor control systems, lighting systems, and many more. With these applications in mind, a contactor is designed to be remote operated, and is most often actuated by control signals sent to it from a low-voltage device, most often a relay, PLC or switch. Typically, a contactor is built to switch heavy loads, and can be made of robust metals, especially to prevent the sparking that results when opening and closing the contacts. This is a critical part of any contactor, for wilful or inadvertent failure to safely handle high-voltage circuits can lead to very dangerous situations, resulting in fires and damage to equipment. A contactor consists of a coil which produces the magnetic field when energied, pulling the contacts in to close them, and complete the circuit, and contacts, which are the metal points that close and open to complete or stop the flow of electricity.
Contacts: In a contactor, they may be normal open or normal close.
Spring: Helps keep contacts open or closed when coil is not energised.Housing: A closed-up housing protects from accidental contact with high voltage and secures all other parts which might be needed, in their respective required positions.
How does a contactor work?
A contactor works on what is known as the magnetic induction (magnetism) principle. What this means is, when the contactor coil is energised, this has the same effect as mechanical magnetism on its internal contacts, bringing them together and closing the contact. When the coil is de-energised, that spring mentioned above pulls the two contacts apart from each other opening it and stopping the electricity passing through it. This action can be quite rapid, generally quoted in milliseconds or microseconds. In fact the contacts are designed such that it will not harm them to frequently open them and close them in firm quick as a whip ticks fashion. They are made from a material like silver which can resist that sort of wear and tear for a long time.
Applications of the contactor
Also known as motor control contacts or simply contact switches. Contactor are used in.Motor control: They are commonly used in the motor starter circuit to switch on and off power to the motors, handy where you do not want to go to each motor to switch it off or on.HVAC: The supply to power the HVAC machines is also controlled by contactors.
Lighting control: With increasing number of buildings coming up most industrial building that is, there is provided a means of keeping an eye on supply of power to the lighting system through contact switches.
Protection from overload: Contact switches oftentimes work together with thermal overload relay switches to guard electrical systems mainly from being burnt out when too much current flows through.
Types of contactors
As is the case with every type of electrical and electronic components, numerous types of contactors abound the electronics and electrical markets worldwide today, most popular you are likely to meet are listed below:
AC: Built for alternating current (AC) circuits; strictly for use (not only though) in controlling motors and lighting systems.
DC: The direct current (DC) complementary contactor that works in exactly the same way as the AC counterpart, except is also suited for dealing with DC power.
Magnetic contactor: The most popular contactor of the lot.
Thermal contactor: Uses a thermal, bimetallic strip to actuate it in response to temperature changes.
Choosing the right contactor
To get the right contactor for a particular application, take into consideration the following:
Current rating: The contact switch should be rated for the amount of current that it would be switching regularly, normally expressed in amperes (A).
Voltage rating: The system voltage or level being powered or controlled need be the same as the rated voltage of the switch in order to prevent failure.
Type of load: Contact wear is influenced mainly by the type of load being switched, thus itbecomes necessary for each contactor to be designed particularly with that load in mind; most popular are resistive, inductive, and capacitive loads.
Environment: Environmental conditions also contribute in determining which contactor is more suitable. The rate of airflow for instance is important in determining electrical connecters where sticking tendency may be due to airtemperature rising to desired level.
Conclusion
We see that understanding designers intent on how they work will aid in making a good choice of the right type of contactor for control high-voltage electrical systems. There is no denying the fact that contactor switches ought never to be far off wherever commodities or goods are being produced in an industrial setting, also in commercial and residential premises for their resilience in taking care of rising current and voltage loads. Be it for motor control, lighting systems or for protection from overload.