INDUSTRIAL APPLICATION OF PLCs IN PAKISTAN:

Following are the main industrial applications of PLCs in Pakistan

WIND TURBINE OPERATIONS:
Alternate energy systems are now very common in Pakistan. PLCs replaces the use of mechanical sensors that were previously used for wind speed measurement and is found to be reliable, affordable and user-friendly. Almost all of the wind turbine power plants uses PLC systems to make the precise measurements and eliminating the inefficiencies. It’s vital that wind turbines have accurate information regarding wind conditions to operate safely, as wind data is useful to record turbulence and to protect the turbine. PLC converts signals from wind speed and directions sensor to better control the wind turbines. Data from the PLCs is transmitted to a control center where engineers perform statistical analysis, program the PLCs and turbine controllers, and analyze data to predict failures before they happen. Information provided by PLC is then transmitted to the control centers where it is analyzed to prevent failures.

CEMENT MANUFACTURING:

Currently there are 26 cement plants operating in Pakistan all of them are using PLC systems to ensure the right quality and quantities of raw materials used for the processes. PLC systems used in cement manufacturing are very comprehensive as there are wide range of analog inputs (temperature, pressure, flow, noise level, height measurement, process values) as well as digital signals that are very useful for equipment safeties and fault diagnostics. This automation has significantly improved plant performance with the reduction in labor cost as all of the information can be gathered in the control center by SCADA which take notice of all the developing problems and take corrective measures.

POWER PLANTS AND GRID STATION:

In Pakistan, power is produced by two vertically coordinated public sector utilities: Water and Power Development Authority (WAPDA) that produces for all of Pakistan (with the exception of Karachi), and the Karachi Electric (K-Electric) for Karachi and its encompassing zones. The independent power producers (IPPs) that also contribute in electricity generation are 42 in total.
There are four major power producers in country: WAPDA, K-Electric, IPPs and Pakistan atomic energy commission (PAEC). 

Power production deals with the generation, transmission and circulation divisions. With respect to this the main aspect is monitoring in all these three territories. The implementation of SCADA in power production increases efficiency of the system that is helpful for optimization and overall supervision of the generation and transmission systems. SCADA enhances the reliability and stability for integrated grid operation.

PLC integrated with SCADA for Power Generating Stations:

With the utilization of PLC integrated with SCADA in power producing stations helps providing flexibility to the system also delivering optimal solution in each and every process.

Automation for Power Distribution System:

Power distribution system includes the transmission of electric power from generating station to the loads with the help of different transmission and distribution substations. Most of the power distribution system depends on manual labor needed for the distribution tasks like interfering the power to loads, monitoring of parameters on hourly basis, fault diagnosis, etc. The implementing SCADA/PLC system to the power distribution not only reduces the cost but also provides automated smooth operations with minimized disruptions.

Programmable logic controllers in substations consistently screen the substation segments and transmits that to centralized PC based SCADA system. In case of any blackouts of power this SCADA permits to distinguish the area of fault in this way without sitting tight for the calls from clients SCADA gives an emergency system to the administrators for recognizing and counteracting it.

Different types of power stations present in Pakistan operating on PLC systems are as follows:

1.      Thermal

2.      Natural Gas

3.      Coal

4.      Hydroelectricity

5.      Nuclear

6.      Renewables

STEEL SECTOR:

In this era of technology demand for electricity has increased with the grown living standards. Most of the power producers are facing difficulties in meeting the increased demands from almost all consumer sectors.

The consumption of industrial sector is about 41% of the total electrical energy generated worldwide.

For iron and steel industries, electricity consumption is about 30% of total production costs.

By taking advantage of incentives in order to encourage users to efficiently use energy so as to minimize load can significantly save electricity cost as well as production costs without negative effects on productivity and quality of production.

Automation is one of the best option available for industries for load management.

Steel has always been the most important engineering material used in the modern era. The steel industry is plays an important role in the economy.

Steel plants processes have complex sequences of operations hence automation plays an essential role. Automation provides information about the plant conditions which helps in maintenance of the plant equipment and make them reliable and available for production.

Automation systems used in the steel industry can be classified as follows.

·         Fixed automation – It is a special purpose dedicated equipment having fixed set of operation. It is used where high production is involved.

·         Programmable automation – Programmable automation system is used where medium to high product volume is involved. In this automation sequence of operation and configuration of the machines is changeable using electronic controls.

·         Flexible automation: This type of automation can be used where variety of products can be manufactured. In this automation system commands in the form of codes are entered in the computer to get optimum output results. It is mostly used where production rates are low and frequent changes are required due to dependency on demands.

·         Integrated automation system: This type of automation performs all operations using information and communication technologies. It makes use of technologies such as flexible machining systems, automated handling machines like robots, automated cranes etc.

There are five levels of automations which are commonly employed in steel industry. These levels are given below.

·         Level 0 – This level usually involves no automation or also called manual control.

·         Level 1 – The level I automation includes DDC (dedicated digital controller) .It is used in production processes. It does not include networking. The level 1 automation systems have capability to handle more complex MIMO (multi input and multi output) systems. They’re operator’s console.

·         Level 2 – This automation level includes supervisory control. It forms a hierarchical control system by combining production process and management information with the process control.

·         Level 3 – Level 3 automation system is an integrated automation system that contains production planning and control functions. Maintenance planning and analysis of data is also included in level 3. Enterprise resource planning (ERP) is a popular software based technology used in level 3 automation.

·         Level 4 – It is similar to level 3 controls but can be easily controlled through satellite from a remote area. Level 4 actually connects customer orders and material and makes capacity allocation to production. 

Fig shows the different level of automation.

Fig Functional hierarchy of a control system at the different level of automation

PHARMACEUTICAL INDUSTRIES:

For the sake of optimized production and enhancements in the supply chain have increased the use of automation technologies across the pharmaceutical industry. Consequently, with the evolution in technology, the process involved in manufacturing of pharmaceuticals have been automated.
The impact of automation systems has transformed the pharmaceutical manufacturing environment.

Continuous Manufacturing and Multi Products:

Earlier manufacturing facilities have to rely on developing the same product every year. To meet the needs of multiple customers flexible facilities are required for which multi-product manufacturing facilities are needed. Hence automation can be employed for such sites that have capability to meet the customer demands accordingly.

Traditional pharmaceutical companies have been slow to find new technologies for continuous production as they have predefined policy of maximum asset utilization on the plant. Therefore, automation helped much in this regard.

 It refers to new tools and procedures that introduces smart decentralized production, intelligent systems that work efficiently and reduces the waste, increasing the production rates with reliability of the equipment.
Automation simply introduces technological advancement that includes some proven solutions and has provided positive and bigger advantage to pharmaceutical manufacturing.

It provides manufacturers full monitoring of operations of the plant and allow them to control, manage and handle the operations of the plant accordingly. This cutting edge technology is making almost everything automated like if a gauge temperature is showing higher than expected reading the system will automatically take the desired action rather than requiring an operator to control the situation.
In addition, this technology uses machine learning algorithms will be able to manage manufacturing lines and production scheduling quickly. Also it can predict due maintenance and the capability to identify and solve issues before they happen.

TEXTILE INDUSTRY:

In most sectors of textile manufacturing process, automation is one of the major key to quality improvement and cost competitiveness. Early modernization and technical developments in textiles concentrated on the automation of textile machines and their processes. Now automation has taken place in all the processes involving textile manufacture i.e. cotton picking, ginning, spinning, weaving, and processing and even to some extent in garment making, resulting in enormous gains in productivity and efficiency. Some of the changes that have come about in textile industry are recapitulated below. 

Automation is one of the key to quality improvement and cost competitiveness in most sectors of textile manufacturing. The technical developments in textiles focused on the automation and processes of textile machinery that results in improved efficiency and high production rates.

Following are the main processing divisions where PLC systems are currently deployed and running successfully.

1). Cotton picking

2). Weaving

3). Ginning

4). Spinning

5). Processing

6). Packing

ROLE OF AUTOMATION IN TODAY’S INDUSTRIAL ERA

In recent years industrial world has undergone a significant transformation in terms of technical innovation and development. Today every industry (process, manufacturing, engineering, automotive, metallurgy etc) requires automation in any form to run its system smoothly and efficiently. Various industries in Pakistan are now making themselves abreast with the modern automation technology in either PLC or SCADA systems form to ensure smoother and reliable operations as well as to eliminate the ghost faults, easy troubleshooting, smooth operations and process inefficiencies. 

There are two main types of automation systems currently being used worldwide PLC and SCADA systems. Although SCADA is still difficult to implement due to its very high cost and scarce skilled engineers and electricians but PLC systems are now deployed in most of the automated industries, plants and processes and are running successfully throughout the country.

PROGRAMMABLE LOGIC CONTROLLERS (PLC)

PLCs are widely used in technological and industrial sector today. PLCs are modular solid state computer with custom programming. PLC is used in industrial control systems for machinery in a wide range of industries, including many of those involved in critical infrastructure. It is replacement of old day’s mechanical relay, timers and counters i.e. mechanical based systems. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was mainly composed of relays, cam timers, drum sequences, and dedicated closed loop controllers. Since these could number in hundred or even thousands, the process of updating such facilities for the yearly model change-over was very time consuming and expensive, as electricians needed to individually rewire relays to change the logic. PLCs are used successfully to execute complicated control operations in a plant. A sequence of instructions is programmed by the user to the PLC memory and when the program is execute, the controller operates a systems to the correct operating specification as per the program logic.

It incorporates three basic features of input, process, and output where everything has to go along well and harmoniously. The input or data should go along with the suitable operation or process in order to produce the intended result or output.

BLOCK DIAGRAM OF PLC SYSTEM:

The PLC receives information from connected sensors or input devices, processes the data, and triggers outputs based on pre-programmed parameters.
Depending on the inputs and outputs, a PLC can monitor and record run-time data such as machine productivity or operating temperature, automatically start and stop processes, generate alarms if a machine malfunctions, and more. Programmable Logic Controllers are a flexible and robust control solution, adaptable to almost any application.

• I/O – The PLC’s CPU stores and processes program data, but input and output modules connect the PLC to the rest of the machine; these I/O modules are what provide information to the CPU and trigger specific results. I/O can be either analog or digital; input devices might include sensors, switches, and meters, while outputs might include relays, lights, valves, and drives. Users can mix and match a PLC’s I/O in order to get the right configuration for their application.

• Communications – In addition to input and output devices, a PLC might also need to connect with other kinds of systems; for example, users might want to export application data recorded by the PLC to a supervisory control and data acquisition (SCADA) system, which monitors multiple connected devices. PLCs offer a range of ports and communication protocols to ensure that the PLC can communicate with these other systems.
• HMI – In order to interact with the PLC in real time, users need an HMI, or Human Machine Interface. These operator interfaces can be simple displays, with a text-readout and keypad, or large touchscreen panels more similar to consumer electronics, but either way, they enable users to review and input information to the PLC in real time.