Selasa, 29 Desember 2009

Utilization of Programmable Logic Controller in World Industry



Utilization of Programmable Logic Controller in World Industry
Today's industrial development, especially the industry in our country, walking very rapidly along with the spread of industrial products, ranging from what is classified as an upstream industry to downstream industries. The complexity of processing raw materials into raw materials, which proceeds either in physics or chemistry, has spurred people to increase and improve the performance of the systems that support these processes, providing a more productive and efficient. One major concern in this case is the use of industrial process control systems (industrial control systems).

In the modern industrial era, industrial process control systems usually refers to the automation control system used. Industrial control systems where the human role is still very dominant (eg in responding to the quantities measured by the process control system with a series of steps the panel settings and switches that are relevant) has been moved and replaced by automatic control systems. The reason is clear reference to the factors that affect the efficiency and productivity of the industry itself, such as human error factor and the level of benefits offered by the control system. One of the control system is very widespread use Programmable Logic Controller (PLC). Its application covers a variety of industries ranging from the tobacco industry, automotive, petrochemical, paper, even to the mining industry, for example in gas turbine control and the advanced industrial unit mining results. Ease the transition from the previous control system (eg from relay-based control system mechanical) and ease of trouble-shooting the system configuration are the two main factors driving the popularity of this PLC.

This article gives an overview mecoba summary of the PLC from the standpoint of their constituent devices.
Is Actually PLC's?
NEMA (The National Electrical Manufacturers Association) defines the PLC as a digital electronic device that uses a programmable memory for internal storage of a set of instructions to implement certain functions, such as logic, sequence, timing, calculation, and arithmetic, to control various types of machinery or processes through the module I / O and digital or analog.

The PLC is able to manipulate the system, execute, and monitor the situation or process on a very fast rate, with the basic data which can be programmed into the microprocessor-based systems integration. The PLC receives input and produces output electrical signals to control a system. Thus the physical quantities and chemical control, before processing by the PLC, will be converted into electrical signals either analog or digital, which is basically data .. Character process itself is controlled by the PLC is a gradual process in nature, namely that the process running order to achieve the expected final state. In other words, the process comprises several subproses, where certain subproses will run after the previous subproses happen. General term used for such a process is inherently sequential process (sequential process). In comparison, the popular control systems in addition to PLC, such as Distributed Control System (DCS), able to handle the processes that are sequential and continuous (continuous process) and the control loop that includes a relatively large.

Counterfeit Penyususnan PLC
PLCs are produced by different companies at the leading control systems usually have their own characteristics that offer the benefits of the system, both in terms of applications (enhancement) and the main module system. However generally every PLC (as your personal computer which tend to standardize and compatible with each other) contains four parts (tools) the following:

The power supply module.
  1. CPU module.
  2. Software modules.
  3. Module I / O.
Power Supply Module (Power Supply: PS)
PS provides a DC voltage to the other PLC module with additional modules in addition to the total current capacity of about 20A to 50A, which is equal to the integral lithium battery (which is used as a backup memory). PS If this fails or the input voltage falls back and forth from the specific value, the memory contents will remain intact. Artificial Triconex PLC, USA, which has even Trisen TS3000 double power supply which means when one of his PS fails, a second PS will automatically take over the system power supply.

CPU Module
CPU module, called the controller or the processor module consists of two parts:
  1. Processors
  2. Memory
Processor functions:
operate and communicate PLC modules through serial buses or parallel there. Execute the control program

Memory, which works:
Storing digital information that can be changed and the shape of a data table, registers the image, or RLL (Relay Ladder Logic), which is a process control program.

In particular PLC also sometimes we encounter several processors in one module, which is intended to support the reliability of the system. Some processors are working together with a specific procedure to improve control performance. Examples of this type is PLC Trisen TS3000 has three processors with a system called Tripple Modular Redundancy.

The PLC memory capacity is also varied. Trisen TS3000, for example, has a 384 Kbyte memory (SRAM) for program users and 256 Kbyte (EPROM) for its operating system. Siemens Simatic S5 has made 16Kbyte EPROM memory and 8 Kbytes of RAM. PLC FA-3S Series has a total memory of about 16 Kbyte. This memory capacity depends on its use and how far you are as optimize the PLC memory space you have, which means that also depends on how much the location of the control programs necessary to control certain plant. Control program for the drainage of fuel in a gas turbine locations would require more memory than the control programs for mechanical robots move round the car body on the installer automotive industry. An additional memory modules can also be given to the main system memory when the need is increasing.
Module Software Program
PLC recognize various kinds of software, including the State Language, SFC, and even C. The most popular use is RLL (Relay Ladder Logic). All of these programming languages are based on a sequential process that occurs in the plant (controlled system). All the instructions in the program will be executed by the CPU module, and the writing of programs that can be done on the state of on-line or off line. So the PLC can control the program writable when he controlled without disturbing the process control is being done. Execution of the software will not affect the operation I / O is in progress.
Module I / O
Module I / O is an input module and output module in charge of the PLC to manage the relationship of external or peripheral devices that can include a host computer, switches, motor units, and various source signals contained in the plant.

Input module
Input module functions to receive signals from sensors peripheral units, and provides signal settings, termination, isolation, and input signal condition indicator. The signals from peripheral devices will be scanned and it will be communicated through the interface module in the PLC.

Several types of input modules include:

- DC input voltage (110, 220, 14, 24, 48, 15-30V) or current C (4-20mA).
- Voltage AC ((110, 240, 24, 48V) or AC current (4-20mA).
- TTL Input (3-15V).
- Input Analog (12 bit).
- Enter the word (16-bit/paralel).
- Input thermocouple.
- Resistance temperature detector (RTD).
- High current relay.
- Low current relay.
- Input latching (24VDC/110VAC).
- Input isolated (24VDC/85-132VAC).
- Input intelligent (containing microprocessors).
- Input positioning (positioning).
- Enter the PID (proportional, derivative, and integral).
- Pulsa high speed.
- Etc..

Module output
The output module activates a variety of devices such as hydraulic actuators, pneumatic, solenoid, starter motor, and display the status of peripheral points are connected in the system. Other output module functions include conditioning, termination and also isolating the signals exist. Activation process is of course done by sending signals to discrete and analog relevant, based on his own character which is a PLC digital devices. Some common output modules currently include:
- Voltage DC (24, 48, 110V) or DC current (4-20mA
- Voltage AC (110, 240V) or AC current (4-20mA).
- Output analog (12-bit).
- Output word (16-bit/paralel)
- Exodus smart.
- Output ASCII.
- Dual communication port.

With the module on the PLC is working to control a variety of plant that we have. Considering the signals are handled varied and requires the processing of information at once, then the system we have certainly had the support device capable of processing in real time and is multi-tasking,. You imagine that in a power generation unit, for example, the PLC you have to work 24 hours to measure the temperature of waste and speed turbine, and then adjusts the valve opening determines the flow of fuel based on temperature information on waste and speed up., In order to get round a generator, wanted! At the same time the turbine lubrication system and alarm system should work well both under the control of the PLC! An operating system tools and reliable data communications course we should use. Cabling technology, the use of fiber optics-based operating systems and real-time multi-tasking kind of Unix, and adequate facilities for the expansion of computer networks is a common thing in the current installation of the PLC

1 komentar:

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