Sizeable electrical power loads by way of vehicles or industrial equipment need a specialized application to switch them on and off. Contactors are an electrical switching device with higher current carrying capacity. This heavy-duty yet compact mechanism is commonly used with electric motors and can be mounted with ease.
With electrical contactors, switching higher power circuits using a lower current is possible. These devices come in large sizes, a yard or meter in length, and small hand-held dimensions. They carry higher contact ratings extending to hundreds of amps.
The current flowing through energizes the electromagnet, which in turn creates a magnetic field. Fixed and moving contacts allow current to pass through to the load. Since contactor contacts are capable of rapidly opening and closing, they can handle larger loads.
Using bifurcated contacts resolves the problem of moving contacts bouncing as they collide with fixed contacts. By employing economizer circuits, the contactor coil drains lesser power during its operation. AC coils need shading to delay the magnetic core from demagnetization.
The Functionality of Electrical Contactors
Electric current enters through one contact and ultimately into the device where the contactor is embedded. Switching on or off an electrical circuit is the primary function of the contactor. You can deactivate a contactor by pulling it out of its parent device through which it operates. Even the absence of a flowing electric supply breaks the connectivity and rules out a strong magnetic field.
Types of Contactors
Electrical contactors can be classified into the following categories:
- Magnetic contactors operate electromechanically without the need for human intervention. Moreover, these are energy efficient and can be remotely controlled.
- The knife blade switch is probably the oldest model of contactors known to have functional and efficiency issues. They pose operational hazards making it challenging for even advancements in technology to overcome.
- Manual controllers are relatively easier and safer to operate plus boast of better efficiency. As the name suggests, these contactors cannot be remotely operated.
How Do Contactors Differ From Relays?
There are many ways that contractors differ from relays; here are some points to note:
- In Load Capacity
While electrical contactors function well irrespective of the current capacity, relays can only be used in low current capacity control circuits.
- In Application
Since contactors are more powerful, they come in handy for high power applications, unlike relays.
- In Safety Components
Safety features in contactors include spring-loaded contacts to prevent internal short circuits and Magnetic Arc Suppressor inserted to reduce or remove sparks. These components which prevent accidents are, however, non-existent in relays.
- In Power Consumption
Relays use smaller electromagnets; hence, they consume less power in comparison with contactors.
- In Switching Speed
You can operate relays using electronic signals as their switching speed is much faster than contactors.
- In Size and Cost
Given that electrical contactors help power high current capacity applications, they are heavier and larger than relays. This difference in size makes contactors costlier than relays. Matching your requirements with the available options is a smart way to gauge the functional benefits better. Nevertheless, it is advised that you consult with leading providers or certified professionals for the same.
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