03-04-2012, 01:42 PM
MICRO Programmable Logic Controllers
[attachment=19409]
INTRODUCTION
1.1 AUTOMATION:-
The basic mean of Automation is to become a system automatic, mean it complete all overgiven task automatically, the defination of automation to analyze and control all the process paramete in the plants or in a machine with the help of the automatic device is called “AUTOMATION”. When a machine or system is controlled by another system or machine then it is called “ AUTOMATIC SYSTEM”.
In this type of system we can use the feedback Controlled Technology for the accurate operation of our system. In an automatic system all the components of the system works automatically. We only required the starting and stopping of the system, remaining system works itself.
1.1.1 TYPES OF AUTOMATION:-
Automated Machine can be subdivided into two main catagories which are as following:
• Open-Loop Machine
• Closed-Loop Machine
Which can then be subdivided into smaller catagories.
Open-Loop Machines are devices, once started, go through in a cycle and stop.
A common example is the automatic Diswashing machine. One dishe loaded into the machine and a button pushed, then machine go through a predetermined of the operation: pre-rinse, wash, rinse and dry.
Larger, more complex industrial operation also used open-cycle operation.
For example, In the production of Car, a singal machine may be programmed to placed a side panel in place of the car and then weld it in a dozen or more location. Each of the steps involved in this process
From placing the door properly to each of the diff. weld.
Take place according to instruction programmed into the machine.
BENEFITS OF AUTOMATIC SYSTEMS:-
We use the automatic system in these days and it is increased regularly, because it has several benefits of an automatic system, some of benefits are as follow: -
1. Increasing productivity: - When a system change in an automatic system, its productivity is increased because there are no losses like tension, fatigue, laziness etc which are introduced in a manual system, so overall product generated in a particular time is increased.
2. Increase quality: - When we change a system in a automatic system the quality of our product is increased because there is no chance of the error due to human beings, and all the system works as they are instructed by the operator.
3. Reduce overall production cost: - When we change a system in an automatic system them overall production cost of the system is reduced, because the manpower is reduced due to automation and the rate of manufacturing is also increased.
4. Increase safety at work place: - The manpower required is reduced and all the work is done automatically by the machine, so the safety of the humankind is increased at work place and the chance of the accidents are also reduced.
5. Flexibility to expand the system:- In an automatic system our system being more Flexible because now we have only change some function of automation devices to change our requirement and our system works being changed, so the flexibility of our system is increased by automation.
AUTOMATION POSSIBILITY :-
1. There is a desire to enhance process efficiency.
2. There is a desire to exercise superior control on process parameters.
3. There is a desire to significantly reduce human interaction.
4. There is a benefit that prevention is better than cure.
5. Repetitive and monotonous jobs is involved and each stage of production needs careful attention of operators to ensure good quality of final products.
6. Hazardous condition of operation exists in plant.
BENEFITS OF PROGRAMMABLE CONTROLLERS:-
1. Programmable controllers are made of solid state components and hence provide high reliability.
2. They are flexible and changes in sequence of operation can easily be incorporated due to programmability. They may be modular in nature and thus expandability and easy installation is possible.
3. Use of PLC results in appreciable savings in Hardware and wiring cost.
4. They are compact and occupy less space.
5. Eliminate hardware items like Timers, counters and Auxiliary relays. The presence for timers and counters has easy accessibility.
6. PLC can control a variety of devices and eliminates the need for customized controls.
7. Easy diagnostic facilities are provided as a part of the system. Diagnosis of the external systems also becomes very simple. Thus easy service/maintenance.
Explanation of Ladder Diagram:-
In first rung the stop switch is connected in series with start switch to activate the control relay. The stop switch is normally close type where as start switch is normally open type. So when the start switch is pressed control relay is activated. The start switch is push to on type so normally on contact of control relay is used to latch.
In second rung the NC contact of float switch 1 and NO contact of control relay is in series with valve A. When start switch is pressed and the liquid level is below float switch 1 the valve A is opened and it is closed when level touches the float switch 1.The NC contact of float switch 2 is latched by the NO contact of valve A so valve A does not opened as soon as the level falls below the float switch 1 level and remain close till the tank is fully emptied.
[attachment=19409]
INTRODUCTION
1.1 AUTOMATION:-
The basic mean of Automation is to become a system automatic, mean it complete all overgiven task automatically, the defination of automation to analyze and control all the process paramete in the plants or in a machine with the help of the automatic device is called “AUTOMATION”. When a machine or system is controlled by another system or machine then it is called “ AUTOMATIC SYSTEM”.
In this type of system we can use the feedback Controlled Technology for the accurate operation of our system. In an automatic system all the components of the system works automatically. We only required the starting and stopping of the system, remaining system works itself.
1.1.1 TYPES OF AUTOMATION:-
Automated Machine can be subdivided into two main catagories which are as following:
• Open-Loop Machine
• Closed-Loop Machine
Which can then be subdivided into smaller catagories.
Open-Loop Machines are devices, once started, go through in a cycle and stop.
A common example is the automatic Diswashing machine. One dishe loaded into the machine and a button pushed, then machine go through a predetermined of the operation: pre-rinse, wash, rinse and dry.
Larger, more complex industrial operation also used open-cycle operation.
For example, In the production of Car, a singal machine may be programmed to placed a side panel in place of the car and then weld it in a dozen or more location. Each of the steps involved in this process
From placing the door properly to each of the diff. weld.
Take place according to instruction programmed into the machine.
BENEFITS OF AUTOMATIC SYSTEMS:-
We use the automatic system in these days and it is increased regularly, because it has several benefits of an automatic system, some of benefits are as follow: -
1. Increasing productivity: - When a system change in an automatic system, its productivity is increased because there are no losses like tension, fatigue, laziness etc which are introduced in a manual system, so overall product generated in a particular time is increased.
2. Increase quality: - When we change a system in a automatic system the quality of our product is increased because there is no chance of the error due to human beings, and all the system works as they are instructed by the operator.
3. Reduce overall production cost: - When we change a system in an automatic system them overall production cost of the system is reduced, because the manpower is reduced due to automation and the rate of manufacturing is also increased.
4. Increase safety at work place: - The manpower required is reduced and all the work is done automatically by the machine, so the safety of the humankind is increased at work place and the chance of the accidents are also reduced.
5. Flexibility to expand the system:- In an automatic system our system being more Flexible because now we have only change some function of automation devices to change our requirement and our system works being changed, so the flexibility of our system is increased by automation.
AUTOMATION POSSIBILITY :-
1. There is a desire to enhance process efficiency.
2. There is a desire to exercise superior control on process parameters.
3. There is a desire to significantly reduce human interaction.
4. There is a benefit that prevention is better than cure.
5. Repetitive and monotonous jobs is involved and each stage of production needs careful attention of operators to ensure good quality of final products.
6. Hazardous condition of operation exists in plant.
BENEFITS OF PROGRAMMABLE CONTROLLERS:-
1. Programmable controllers are made of solid state components and hence provide high reliability.
2. They are flexible and changes in sequence of operation can easily be incorporated due to programmability. They may be modular in nature and thus expandability and easy installation is possible.
3. Use of PLC results in appreciable savings in Hardware and wiring cost.
4. They are compact and occupy less space.
5. Eliminate hardware items like Timers, counters and Auxiliary relays. The presence for timers and counters has easy accessibility.
6. PLC can control a variety of devices and eliminates the need for customized controls.
7. Easy diagnostic facilities are provided as a part of the system. Diagnosis of the external systems also becomes very simple. Thus easy service/maintenance.
Explanation of Ladder Diagram:-
In first rung the stop switch is connected in series with start switch to activate the control relay. The stop switch is normally close type where as start switch is normally open type. So when the start switch is pressed control relay is activated. The start switch is push to on type so normally on contact of control relay is used to latch.
In second rung the NC contact of float switch 1 and NO contact of control relay is in series with valve A. When start switch is pressed and the liquid level is below float switch 1 the valve A is opened and it is closed when level touches the float switch 1.The NC contact of float switch 2 is latched by the NO contact of valve A so valve A does not opened as soon as the level falls below the float switch 1 level and remain close till the tank is fully emptied.