If you have ever wondered how it is that industrial and commercial processes are powered, you need to look no further than the invention of the electrical motor. Depending on how much energy is needed, you should expect to find multiple motors being used to operate a single process. One of the basic tenets of motors is this: Whenever a motor is used, it has to be controlled.
It is fairly easy to control a single motor because it usually requires nothing more than a switch or some sort of starting mechanism. However, once you have multiple electric motors in place, the ideal scenario would be to have a single hub from which all of the motors can be controlled. This led to the invention of motor control centers that were in use as early as 1850 by the automobile manufacturing industry.
In order for this complex setup to work, there are several motor control components that need to be put in place in order to control the operation of motors. Below are some of the components that typically make up a motor control mechanism.
Heaters
One of the main problems that exists in motors is that of condensation, especially in areas that are damp and/or have a high degree of humidity. The solution to this is to maintain a winding temperature that is 5-10oC higher than the surrounding air temperature, and the component that will get this job done is the heater. They become energized when the motor is disconnected from its power source, which allows the motor(s) to remain functional the next time they are used.
Control Relay
The control relay are electromagnetic switches that can control an electrical circuit by opening or closing the contacts within another circuit. It is powered by a low power electrical current that can control whether a larger electric current is turned on or off. There are two types of time-based control relays: The time-delay opening relay will open its contacts after the relay coil has been de-energized, while the time-delay closing relay will close its contacts after the relay is energized.
Overload/Thermal Relays
Depending on its application, a motor may need to be running for an extended period of time and its shutdown could have serious consequences. One way in which a motor can malfunction is through overheating. In order to prevent this, a temperature-sensitive device called a thermal relay (or overload relay) that can sense the current that is going into the motor. If the current is at a high temperature for an extended period of time, the relay will open the contacts that are carrying the current to the contactor coil, de-energizing the coil and interrupting the transfer of power to the motor. These components come in various classes that are separated based on the time that it will take for them to respond to motor overload.
Contactors
These contactors are electricity-powered switches that are designed to open and close a power circuit. They are similar to control relays with the key difference being that it deals with higher amounts of electrical power.
Starters
Also known as a motor controller, a starter is designed to handle a motor’s performance. Various aspects such as speed, torque, rotation and turning the motor on and off are handled by the starter. The starter can be a single device or a group of devices. The simplest form of a starter is a switch that can connect a motor to a power source, although modern technology combined with the use of multiple motors at once has resulted in motor starters providing the user with the option to simultaneously control multiple factors of the motor at once.
Buckets
Motor control buckets are compact enclosures that contain various parts such as contactors, motor starters, overhead relays and more. They are designed with the purpose of quick installation and removal of the control part of a motor control center. They make the installation of motor controls far easier due to the fact that the entire enclosure contains all the necessary parts for operating the motors.
Those are the basic components that make up a motor control mechanism and are the most important when it comes to the operation of the actual motor itself. Motor control centers are able to accompany many kinds of devices in the modern age, but this only means that you need to double-check all of the parts in the motor to ensure that it is the right one for the job.