PLC Programming

• What does ‘PLC’ mean?

A PLC (Programmable Logic Controllers)  is an industrial computer used to monitor inputs, and depending upon their state make decisions based on its program or logic, to control (turn on/off) its outputs to automate a machine or a process.

• NEMA defines a PROGRAMMABLE LOGIC CONTROLLER as:

“A digitally operating electronic apparatus which uses a programmable memory for the internal storage of instructions by implementing specific functions such as logic sequencing, timing, counting, and arithmetic to control, through digital or analog input/output modules, various types of machines or processes”.

• Traditional PLC Applications

*In automated system, PLC controller is usually the central part of a process control system.
*To run more complex processes it is possible to connect more PLC controllers to a central computer.

• Major Types of Industrial Control Systems

1. PLC 
2. DCS
3. Embedded Control 
4. SCADA

What Is An Electrical Machine?😎

An electrical machine is a device which converts mechanical energy into electrical energy or vice versa. Electrical machines also include transformers, which do not actually make conversion between mechanical and electrical form but they convert AC current from one voltage level to another voltage level.

Electric Generator:An electric generator is an electrical machine which converts mechanical energy into electrical energy. A generator works on the principle of electromagnetic induction. It states that whenever a conductor moves in a magnetic field, an emf gets induced within the conductor. This phenomenon is called as generator action.

A generator basically consists of a stator and a rotor. Mechanical energy is provided to the rotor of a generator by means of a prime mover (i.e. a turbine). Turbines are of different types like steam turbine, water turbine, wind turbine etc. Mechanical energy can also be provided by IC engines or similar other sources.

Electric Motor:A motor is an electrical machine which converts electrical energy into mechanical energy. When a current carrying conductor is placed in a magnetic field, the conductor experiences a mechanical force and this is the principle behind motoring action.

Just like generators, motors also consist of two basic parts, stator and rotor. In many types of motors, electric supply needs to be provided for both stator and rotor winding. But in some types, like fixed magnet motors and induction motors, supply may be necessary for only one winding. Electromagnetic force between the two windings causes the rotor to rotate.

AC motors

Synchronous motor: 

• AC motors can be divided into two main categories first one Synchronous motor  
Stator has axial slots which consist stator winding wound for a specific number of poles. Generally a 
• salient pole rotor is used on which rotor winding is mounted. Rotor winding is fed with a DC supply with the help of slip rings. A rotor with permanent magnets can also be used.

• Stator poles rotate at the synchronous speed (Ns) when fed with a three phase supply. The rotor is fed with a DC supply. The rotor needs to be rotated at a speed near to the synchronous speed during starting. If done so, the rotor poles get magnetically coupled with the rotating stator poles, and thus the rotor starts rotating at the synchronous speed.
• Synchronous motor always runs at a speed equal to its synchronous speed. 

          i.e. Actual speed = Synchronous speed or  N = Ns = 120f/P

SYNCHRONOUS MOTOR

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This Blog is made for Educational purpose so as to help the fellow Electrical engineering students and to spread the knowledge about the latest Engineering.