Which drives are used in industrial automation?
Industrial drives are used in different applications. here different types of motors are used based on requirements. The electric motor is the industrial drive, it is used in different techniques. Special motors and gears were developed to suit all applications. induction motor, squirrel cage induction motor is used for speed applications. wound rotor induction motor used in high starting torque, low starting current, and speed control over a limited range.
The type of electric drive and control gear for an application is determined by the Duty, whether heavy or medium light, starting torque, limitations on starting current, speed control range and its nature, need for automatic control, environmental conditions. For all applications, an asynchronous motor is suitable.
For production equipment, consists of components are the prime mover along with its control equipment, the motion transmitting device, and the actual apparatus or equipment. In the production unit, these components are imparted motion. Electric drive is the combination of the shaft transmitting motion and associated control equipment are called electric drive.
In the form of advancement, there are 3 types in industrial drives, they are,
Group electric drive
It had a single motor with sufficient capacity to drive an entire group of machines. This drive is inefficient, difficult to control, and unsafe. These drives are used in old days. Now, this drive is not using.
In the individual drive
There is one motor for each working machine, in the individual drive. An integral part of the machine is the electric motor and can be specially designed for machines based on the need.
Multi motor drive
The multi-motor drive is the third eye. This drive consists of more than one motor for each machine. Metal cutting machine tools, rolling mills, paper-making machines, etc are multi-motor drive examples.
In industrial drives, different types of load characteristics are constant torque type load, torque (twisting force)proportional to speed, torque proportional to the square of the speed, torque inversely proportional to speed.
Industrial drive applications are,
In a crane, both AC and DC drives are used for different operations.
For hoisting and lowering operation, AC slip ring motor, ward Leonard, controlled DC shunt motor, and DC compound motor drive has been used.
For crane travel operation, an AC slip ring motor drive has been used.
For slew and swing action operation, an AC slip ring motor or DC shunt motor drive has been used.
For boom hoist operation, an AC slip ring motor drive has been used.
Rolling mill drives
DC motors and AC slip ring motors with speed control drives are been used for rolling mills.
The inherent characteristics of DC motors are the best for the rolling mills. Speed control is affected by grid-controlled mercury arc rectifiers. For roughing and rolling mills, AC slip ring motors are suitable and for this, speed control is not required. Here, the efficiency is low.
The commonly used drives are,
Slip ring induction motor,three-phase shunt-wound commutator motor, ward Leonard controlled DC motor, Cascade controlled AC motor, DC motor with transformer step switch control.
Textile industry drives
The special type of textile industry drives is, weaving and sinning.
In the presence of large power losses, the motors used in the weaving mills have a good cooling capacity to keep the temperature within limits. For cotton, silk and nylon have, small motors of temperature insulation are used to drive looms. For wool, the rating of the motors may be 2-3 hrs. These motors run at 750-1000 rpm.
The 3 types of drives in the spinning mills are
A 4 pole or 6 poles squirrel cage induction motor, a pole amplitude 4/6 or 6/8 poles induction motor, two separate motors to be runs at 1500/1000 or 1000/750 rpm. Here the motor must be started with controlled torque.
Paper industry drives
The drives of the paper industry are pulp making and paper making.
In the pulp-making process, they are chemically treated with alkalis. For these drives, synchronous motors are been used. In paper making the logs of wood are booted. The power requirement of these motors is less than the grinder motors. These motors require high starting torque.
- Belt conveyor drive
- Blowers fans
- Machine tools
- Jaw crusher
- AC drives
- Servo drives
Importance of DC drives in industrial automation
The DC drive has a smaller footprint. So a smaller footprint is clearly gained in ease of installation and minimizes the material costs. DC motor produces thousands of horsepower.