Motor control systems are crucial to the protection and functioning of industrial equipment usually powered by electric motors. Basic motor control technologies are widely integrated in devices. Also, motors are crucial components in several electrical engineering projects. It is important to have a good understanding of motor operation and motor control. Also, you should know how motor control impacts engineering projects.
What are Motor Control Devices?
Motor control devices govern the functioning of an electric motor in a controlled manner. Also, these devices can help to start or stop a motor fixed to a machine. Motor control devices are also known as motor controllers. Also, they can be controlled automatically or manually. Motor controllers control the operation of an electric motor.
Also, motor controllers can regulate or limit the torque of an artificial system and protect against faults and overloads. In artificial lift applications, motor controllers are devices integrated with VFDs or switchboards to regulate the prime mover‘s operation. Also, some motor control devices include additional features like data logging and data collection.
Motor controllers often use automatic or manual methods to control speed, stop, start, and reverse a motor. Also, they are often used with both AC and DC motors. Controllers can link the motor to the supply of electrical power. Furthermore, they may protect the motor from overload. Motor control devices can check the field circuit of the motor or identify issues like incorrect phase sequence, low voltage supply, and incorrect polarity.
Some motor control devices restrict the inrush starting current and as such, enable the motor to increase itself and link mechanical load slower than direct connection.
Functions of Motor Control
Motor control systems perform some basic functions. We have mentioned some of their functions earlier. We will be discussing these basic functions extensively in this section.
One of the primary functions of a motor control system is starting the motor. Motor controllers can employ several methods, based on the circuit’s requirement. However, the across the-line starting is the simplest method. This method involves linking the motor directly to the power line. In some cases, the motor may need to start at a low speed and increase to full speed. Also, this is usually known as ramping.
This is another important function of a motor control system. Also, the easiest method to stop a motor is to disconnect it from the power line. However, the motor may need to stop more quickly in some cases.
Motor and circuit protection
Motor control offers protection for the motor and the circuit components. Circuit breakers and fuses are usually integrated for circuit protection. Also, overload relays help to protect the motor.
Jogging and inching
These are methods motor control employs to move a motor with short power. Jogging and inching are usually performed to move a load or motor in desired position. However, there is a slight difference between the two. You can accomplish jogging by momentarily linking the motor to full line voltage. On the other hand, you can achieve inching by linking the motor to reduce voltage.
Types of Motor Control Devices
Motor controllers can be either controlled manually or automatically. Also, you can control them in a remote manner. Motor control devices offer protection against several degrees of electrical faults and overloads. However, these controls are in different categories based on the type of motor they can operate.
Reduced voltage starters
For this type, two or more starters start a motor in low voltage conditions. Lower voltage is at the motor terminals via a series of autotransformer and inductance. Also, this helps to minimize the inrush electric current and the starting torque. The starter will send full voltage to the motor terminals immediately the motor gets to a particular portion of its top-load speed.
These motor control devices integrate advanced microprocessors for regulating electronic devices’ power used in an electric motor. Also, these motor controllers regulate the load on a motor and ensure he torque matches with the recorded load.
To start small motors, plug the electric switch in the receptacle and then switch on the power button. Larger motors require contractors or motor starters. Moto starters are switching units that power an electric motor. After it has been powered, there is a connection between the direct on-line starters and motor terminals.
These motor control devices have unique features such as fast acceleration rate, precise speed control, and precise closed-loop positional control. Also, these control devices integrate position feedback to close the control loop.
Adjustable-speed drives are unified combination of devices that allow operators to drive and also adjust a mechanical load’s operating speed. Such drives include power converter, speed controller, and various auxiliary devices and equipment. An electrical adjustable-speed drive features a speed controller and an electric motor.
Types of Motor Controllers and Drives
Alternating Current (AC)
AC motor controllers and drives can adjust the frequency power of the motor thereby, modifying the input power to motors. This helps to regulate the torque and output speed. You need to consider key specifications such as power rating, drive operating mode, loop system classification, and motor type. Also, AC motor controllers are primarily integrated in process applications to regulate the speed of blowers, pumps, etc.
Furthermore, they are known as AC inverters or variable speed drivers. The controller supplies the drive’s control signals. AC motors may not have much speed response to adjust terminal voltage. Therefore, controllers for AC adjust rotor circuit resistance. AC motor drives regulate the speeds of motors that drive fans, pumps, and more
Direct Current (DC)
DC motor controllers and drives adjust the alternating current source to modify the input power. Key specifications here include drive operating mode, communication interface, intended application, and motor type. Also, these controllers and drives help in regulating torques and motor speeds for electric vehicles, machine tools, and more. The controllers in direct current motors may adjust the voltage use for the motor.
DC motor drives regulate permanent magnet DC motors operating from AC sources. Also, these drives feature low-speed torque, which makes them ideal for cranes, winches, and more
Steppers are electronic devices that change the input power by simply adjusting the source of alternating current to a “stepped” or pulsed current output. Stepper motor controllers and drives are mainly integrated in motion control applications in construction and manufacturing environment. Also, they are widely used in controlling torques, motor speeds, and position.
These motor controllers and drives are commonly used in applications like robotics, machine tools, and other types of machinery.
Considerations in Selecting Motor Controllers and Drives
You need to know the motor type when selecting motor controllers and drives. If you are deciding to use AC or DC drives, you will need to consider some factors. For instance, DC motor drives feature good low-speed torque and as a result, this makes them an ideal option for cranes and winches. Also, these drives are suitable in applications where you need to lift loads without a “running start.”
On the other hand, AC motor drives are ideal for applications that need to regulate the speeds of motors. Therefore, they are widely used in fans and pumps. AC motor drives increase efficiency by setting the speed of fan and pump to match requirements.
The nature of application is another consideration when choosing between AC drives and DC drives. AC drives are specially designed for constant or variable speed applications.
Types of Control Systems in Motor Controllers
There are three types of control methods in motor control systems. These are automatic, manual, and semiautomatic.
In automatic control, some actions initiate automatically. Once the operator sets the control conditions, the motor control system will operate on its own. The cooling and heating system in several homes is a good example of automatic control system. Also, the control circuit comprises sensing devices that shut the system automatically when there is an unsafe condition like excessive current.Automatic control integrate current sensors or internal timers to increase the motor.
In manual controls, the operator must initiate any change. Also, manual controllers are usually simple devices that directly link the motor to the line. However, this type of control may not protect overload or release low-voltage. You can accomplish manual control by connecting a switch in series.
This involves the use of pressure switches, push buttons, and other sensing devices to regulate the operation of a magnetic starter or contactor. Also, the starter links the motor to the line and other pilot devices to regulate the coil of the starter.
Motor Control Components
As explained earlier, there are various types of motor controls. Each of these motor controls integrates different mechanisms. Therefore, they are different types of motor control components. It is crucial to know the function of these components.
Motor circuit breaker
This component protects against short circuits and overloads. It works in a similar way with an ordinary circuit breaker. When short circuit or overload occurs, the device switches off the motor. You can fit in auxiliary contacts to offer a tripping feedback details to a pilot light indication. Furthermore, you can use motor circuit breakers with contractors for the load’s control.
Thermal overload relay
Thermal overload relay offers protection against current overloads that may result in overheat and service disruption. Also, this relay uses bimetallic strips. These strips heat up when overcurrent occurs.
This is an electro-mechanical devices that switch off or switch on motor load. To switch on this contractor, voltage has to be applied across the coil terminals. A contractor works better than relay as it is ideal for higher power rating. Also, a contractor isn’t only used for interrupting short circuits only. It serves other purposes.
In reality, mini contractors function like contractors. However, they are much smaller. This offers reliability and efficiency where space saving is necessary.
Motor control accessories
These are peripheral devices attached with a motor to ensure its smooth operation. There are various motor control accessories based on the motor need.
What are DC Motors?
DC motors convert electrical energy into mechanical energy. They operate on DC power-non-sinusoidal. Also, DC motors include basic parts such as stator, rotor, field magnets, and commutator. These motors function based on a principle of electromagnetism introduced by Faraday. This principle states that when you place current-carrying conductor present in the magnetic field, it feels and experiences a specific force.
DC motors are available in different types based on their construction. The brushed or brushless, series, and permanent magnet, are the most common types of DC motors.
Types of DC Motors
Brushed and brushless motors
Brushed DC motors use carbon brushes to deliver current from the armature. These brushes are close to the commutator. The brushless DC motors don’t have graphite or carbon brushes. Also, these DC motors comprise permanent magnets. Furthermore, brushless DC motors integrate electronic circuits to regulate the direction of speed and rotation.
Series-wound DC motors
Series motors have their field windings and stator windings usually connected in series. Also, the field currents and armature currents are always equal.
Permanent magnet DC motors
These DC motors comprises a rotor with two opposing permanent magnets. When you pass DC, these magnets deliver a magnetic field flux. This makes the rotor to spin in ant-clockwise or clockwise direction. One advantage of this type of DC motor is that it can function at synchronous speed.
Shunt DC motors
Shunt DC motors comprises field windings and armature which are usually connected in parallel. Also, both windings get the same voltage supply due to the parallel connection. Shunt DC motor can feature excellent speed regulation. However, they don’t have high starting torque.
What RayMing Offers You
RayMing has the experience and sophisticated manufacturing facilities to help you design your motor control project. Regardless of your motor control needs, we offer you the best. We work with a team of experienced engineers devoted to offering the best solution to your motor controller needs.
Also, our motor control devices are ideal for use in different applications. We would like to provide the best motor controllers for you. Furthermore, we offer support services such as assembly and technical support.