All You Must be Aware of Contactors
An electric contactor is essentially a tool for electrical switching. It is employed to turn on and off electrical circuits. Although it is a unique kind of relay, contactors and relays function fundamentally differently. Relays are utilized for lower current applications, whereas contactors are often employed in applications involving larger current carrying capacities. Contactors are small and simple to mount in the field. These devices often have several contacts. The majority of the time while the contactor coil is operated, the contacts are generally open and supply operational power to the load. Electric motors frequently employ contactors.
Different varieties of contactors exist, and each type has a unique set of characteristics, uses, and capabilities. A wide variety of voltages, from 25VDC to thousands of volts, and currents, from a few to hundreds of amps, may be handled by contactors. These devices also exist in a variety of sizes, ranging from compact hand-held models to big ones that can measure up to a meter or a yard on one side.
As a result of its capacity to withstand current well over 5000 amperes and high power of well over 100kW, contactors are most frequently utilized with high-current loads. Arcs are created when strong motor currents are interrupted. These arcs can be diminished and controlled with a contactor.
Principle of a Contactor’s Operation
The electromagnet is energized by the current passing through the contactor, which is how the contactor functions. The electromagnet then produces a magnetic field after being powered. As a result, the armature is moved by the contactor’s core. A normally closed (NC) contact is then used to complete the circuit between the fixed and movable contacts, enabling current to flow through the contacts and into the load.
The coil is de-energized and the circuit is opened when the current is ceased. Because the contactors’ contacts can open and close quickly, they can support heavier weights. Moving contacts may bounce when they quickly collide with stationary contacts because a magnetic contactor is made to open and close connections quickly. Many contactors employ bifurcated contacts to reduce bouncing.
The contactor coil’s current input can be either AC or DC (available in different voltage ranges between 12VAC or 12VDC to 690VAC or 440VDC). The contactor coil consumes very little electricity when it is in use. Economizer circuits are used to minimize the power consumed by the contactor coil while it is operating.
Shading coils are included with contactors that include AC coils. Otherwise, every time the AC reaches zero, the contactor will clatter. To prevent chattering, shading coils can postpone the magnetic core’s demagnetization. DC coils don’t require shading since the flux they create is constant.
What a Contactor Does
The electromagnet produces a powerful magnetic field when electric current flows through the contactor. An electrical arc is produced when the armature is drawn into the coil by the magnetic field. Electric currents enter the device in which the electrical contactor is implanted through one contact. As a result, the contactor’s job is to turn an electrical circuit on or off. By including a thermal overload relay, overloading of the circuit may be avoided.
