Design of a SCADA System

1. Introduction:

The main purpose of this assignment is to design a simple SCADA system to monitor and provide supervisory control of a Bytronic Associates Industrial Control Trainer (ICT) through an Allen- Bradlley Micrologic 1000PLC using the Sistemi Winlog Pro software. From the design of PLC ladder logic program which was developed using RS-logic for the ICT, this assignment of the system will add a higher level of control through software and provide a beginning to the industrial SCADA systems.

Supervisory Control and Data Acquisition (SCADA):

SCADA is Supervisory Control and Data Acquisition. In 1993, SCADA system was required to examine the site for the distribution systems and also for the electrical supply. There was a discussion on the SCADA system that which system would be more a suitable for the site. Almost for each and every packaged systems are combined with the complete SCADA system purchase which is different to the method of basic component as when it is used in single meters. As we are aware of placing both the meters into the switch gears at the substation and also in building switchgears. It is more effective estimated for the SCADA systems to examine the status of electrical power supply systems.

In 1994 using the Intelligent Electronic Devices (IEDs)and a DOS based SCADA software package are utilized by the Utility department to start the installation for the SCADA systems. The energy management department is one of the departments in the Utility division required to collect the data from the building meters. The IDEs which provide a communication to the SCADA software as well as an analogue output signal (KW) that can be read by the building energy management system. In this building energy management system, it records the signal to track the electrical energy demand and Kilo Watt Hours (KWH).

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The SCADA software is a graphical package using a Window NT Operation System. This system is manufactured by the Power Measurement Ltd (PML) provides the programming required to include real AutoCad site map, a diagram and also to present the accurate time information on the header of the graphical conditions. Objects like switch status, all the power system parameters, alarms and so on. Additionally, this system also allow the facilities operations like utility system, bitmap to achieve the big pictures to set at the background, and also the channel down to the single line as required. SCADA system automatically generates an alarm and can also easily expandable as per the application required. The new systems can easily expandable and flexible to the use as IDEs meter are added.

The following are the function that are utilized more and more as the SCADA system is expanded.

• Automatic reporting will be taken with the replacement of manual meter reading.
• They need to respond quickly when the real time alarms and data operators the information.
• The Utility Department can be practical in providing the customers about the quality information.

The main benefits of using the SCADA software are

1. Switching and Paralleling Operations:

Verification of the physical change in the switch operator position was not accessible while using of remote SCADA applications

1. Power Quality:

As needed, generally after a result or upon query from building users the power quality reports are requested.

1. Hospital and Medical School Emergency Services Status:

From the Cogeneration Plant, Hospital Emergency Power Feeders are monitored to verify the accessibility of the services, on a continual basis. This prevents the remote possibility that the service is not available or available.

1. Outage Record:

Position incident analysis is essential to avoid reoccurrence of similar outages and power failures.

1. Substation Security Fires and Door Alarms:

Early on in the design of the SCADA application, it was determined that fire/smoke detectors were required in all substation switch gear rooms. This utility, along with the door alarm contacts, provides the system operators with the ability to respond immediately to these types of actions.

2. System Description:

PLC Diagram Description:

In PLC the programs are fabricated based upon the ‘gates’ simultaneously with the inputs, timers, counters, outputs, internal memory bits, analog inputs, comparators, analog output etc.

Inputs: The physical connections that are connected to the PLC are switches, pushbuttons, sensors and anything which acts like a switch or signal to the state of ON and OFF position. The voltages that accept to some of the devices are 24V DC and some may not; it may vary.

The switch when it is in ON state, then status of the device bit is ‘1′ and when it goes to OFF state the status of the device bit is ‘0′.

Output: The result that appears from the input devices is the communication between the PLC and other terminals. They are used to control the solenoids, sensors, and connectors etc to on and off position.

In the PLC, there are 8 sensors and 5 actuators were used. The result from each sensor response the actuators and other sensors to perform the task. These eight sensors has different task they are

• Sensor1: It detects the presence of peg in the upper sort area.
• Sensor2: It detects the components in front of the solenoid at the upper sort area of the ring chute.
• Sensor3: It detects the presence of ring in assembly area.
• Sensor4: It is used to commence assembling.
• Sensor5: It is used to terminate the assembling.
• Sensor6: It is used to detect the complete assemblies.
• Sensor7: It is used to detect the components at the lower sort area.
• Sensor8: It is used to detect the components and assemblies near the reject area solenoid.

The purpose of 5 actuator which are used in PLC area are

• Actuator1: It drives the upper chain conveyor motor.
• Actuator2: It drives the lower chain conveyor motor.
• Actuator3: It knocks the ring in the ring chute.
• Actuator4: It releases the ring into the assembly area.
• Actuator5: It rejects the unassembled components.

Relay: A relay is a switch which is operated on the electromagnetic.

Counters: when a pre-assigned count value is reached, the digital counters are in the form of relay contact.

Timers: Timer consists of internal clock, a count value register and an accumulator which is used to count the time.

When peg and ring moves in the upper sort area, the peg moves into to the peg chute through the detection of the sensor1 and the ring moves into the ring chute through the actuator 3. And the actuator 4 is to allow the ring in to the space where the sensor 3 detects the ring for the assembling the ring into the peg in the lower sort area. The sensor 6 it to detect the complete assembled components. The actuator 4 has some delay time for allowing the ring in to assembling area. The sensor 8 is to detect the unassembled component and the actuator 5 is to reject the unassembled components.

Using the winlog Pro software, the PLC system can be operated through the ladder program by shutting down the RSlogix and assigning the sensor input pins to the digital gates and actuator output pins to the digital gates.

These functions are performed by four kinds of SCADA components:

• Sensors (either digital or analog) and control relays that directly interface with the managed system.
• Remote telemetry units (RTUs): These are small computerized units deployed in the field at specific sites and locations. RTUs serve as local collection points for gathering reports from sensors and delivering commands to control relays.
• SCADA master units: These are larger computer consoles that serve as the central processor for the SCADA system. Master units provide a human interface to the system and automatically regulate the managed system in response to sensor inputs.
• The communications network that connects the SCADA master unit to the RTUs in the field.

3. Requirements:

The minimum requirements for the SCADA to perform and control the operation of PLC manually are

• By replacing the physical push buttons, providing start/stop to control the ICT from the SCADA.
• Display the state of all sensors and actuators using the digital gates displays such as LED or animations.
• Display the count of the number of rings in the chute at any time (this may also extend to the number of completed assembled and rejected components.
• Provide a means of resetting the ring count a value among 0 to 5 (in the event of malfunction).
• Create a template with a background bitmap that is either a schematic diagram of the ICT or the actual photograph of the kit.
• At least one alarm condition example when a component is rejected or the ring in the chute is more than four.

Constraints:

• In the numerical gates of winlog pro, the LED components cannot be kept because these are used only for counting the rings in the chute and also for the rejecting the components in the chute.
• In the digital gates of winlog pro, the sensors, actuators, LED and switches are kept. It does not accept the counts.

4. SCADA System Design:

The design of a simple control application based on the micrologix DF1 protocol, but the design of more complex systems can be solved using the SCADA. It is easy to understand and approach the winlog Pro software and also to communicate the other devices.

For every new application, the system has to know the external devices, addresses and communication protocol to communicate from one device to the other devices.

In PLC, the program runs between the one of two states for every second in order to maintain the count. According to the SCADA, for each state the LED will be shown and also

for the count will be shown. The PLC program will be started and stopped by using the switch on SCADA.

For creating the variables database devices in the gates of Winlog Pro software, we have to consider the numeric, digital and event alarms according to our applications.

Numeric gates consists of all the variables that refers to the analogue quantity like counts, set points and so on that can expressed in the form of a bytes, a word, a double word, an integer or by a floating point variable. In this application, the numeric gates are used for the counting, rejecting components, complete counts and also for resetting of both complete and reject counts.

Digital gates consists of all the variables that refers to the digital status like alarm conditions, sensors, actuators, configuration option and so on. It can be expressed by a single bit. In this application, the digital gates are used for the input sensors, output actuators and for solenoids and also for switches and pushbuttons.

Event/alarm is also used in this application for the purpose of showing the rings in the chute if the rings in the chute are more than four. This configuration is used for the intention of activating the solenoid.

The following table shows, the numeric variables configurations are made according to the applications are;

Continuation with the table

The following table shows, the digital variables configurations are made according to the applications are;

The following table shows the event/alarm gates configuration are made according to the applications. And this gate cannot read from the devices but the status will be displayed while at runtime. This gate is provided for the attention of the ring in the chute if the ring in the chute is more than four and we also can create more alarms using this gate configuration.

After creating of the gates configurations, we must save it and create the new templates in order to get all the gates for the application and these gates are used for each and every achievement to perform the operation on the particular gates configuration. After adding all the gates, insert all the active label objects like LED, switch and so on and also include the gate to each label to perform the operation when the gate is used in the ladder program. After

completion of adding all the gates, label, chart and bitmap, save the complete configurations. And execute the program.

After the completion of the template design, we must assign the simple code using the name as “Main” in the Winlog Pro code. It is used only for the function that will open for the main template at the application startup.

The following figure shows the final template design that’s required for the applications are;

The above figure represents the complete design of template after arranging all the gates and chart and bitmap.

5. Testing:

After the creation of the templates and Winlog Pro code in the software, close the Winlog Pro and run the RSLogix 500 to create the program and download the Micrologix 1000 ladder program listed in the section. After downloading, go to the Run mode and shutdown the RSLogix 500 and also RSLogix service.

Restart the Winlog Pro software, to run the project in project manager and select Execute from project menu. Then after executing the project, it will moves in run mode to start the project according to the application requirements. Winlog Pro samples variables from devices and processes the results in graphical representations.

When the project that where done by the users to startup then it automatically achieves the main templates.

By clicking the switch object label, we can start and stop the execution of the program. When the program is in running mode, we can see the number of rings that the actuator 3 pushes into the chute and the peg that enter into the peg chute by the detection of the sensor 1

And if the ring in the chute is more than four then the alarms will be in active (blowing condition) mode that informs the ring can’t allow into the ring chute more. The count display the number of ring in the ring chute and edit box is to editing the value that enter in it. By clicking the toggle switch, we can reset both the completed assembles and rejecting components. We can select the chart to show the graphical representation of the counts and digital like pushbutton and switches. The chart also displays the group of variables that we want to display.

The below figure displays the switch button is in ON condition and the counting of ring in chute is 5. If the ring count is more than four in the chute then the alarm blows. And resetting all the completed assembles and rejected assembles. The chart 1 describes the switch buttons (black color) and pushbuttons (blue color) when it is in ON condition. The chart 2 describes the count of the rings in the chute (green color), completed assembled components (lite blue color) and rejected components (red color).

The below figure shows the counting of rings in the chute (green color), completed assembled components (lite blue color) and rejecting the components (red color) when the switch button is in ON condition.

6. Discussion:

Utility System Operators need to be able to continue to remotely and instantaneously, identify electrical Power System Failures at any location in the distribution system. Accurate real time alarming and historical information is needed to continually meet the needs of a diverse community of energy users. A continuation of the demands for high reliability and accurate performance and trending data is paramount is the long term benefits of the SCADA systems.

Approaching the SCADA system design for an application is the first time and in particular Winlog Pro software, it can be easily to communicate with other devices using the RS-232 9pin connector.

Winlog Pro software can accessible easily and understand quickly to the external devices. For different applications, the design of the system for each device should be addressable and the list of all the variables can read or write to the devices. And for the applications the gates configuration should be addressable. Depending on the ladder program the address should be made and we can design different templates.

Without any restrictions of all the winlog pro licenses software, it can provide the functions, development tools and communication protocol. The software toolbox acknowledges the continuous efforts of sielco sistemi to make the winlog pro more competitive and attractive. This powerful, low cost and easy to use SCADA software is indeed collecting increasing agreement among Italian and international users.

Winlog Pro is simple, flexible and more economical in real time applications. It provides the differ tool like gates builders, templates, code builders. It allows the drivers to interface and communicate with all the electronic devices like PLCs, I/O modules and so on.

Conclusion:

Using the Winlog Pro software, the results that are required for the project are achieved. Using this software, we are assigning all the object labels to the gates configuration. The counts the numbers of rings are assigned to the numeric gate and the digital gates like LED, sensors and actuators and solenoids are assigned to this gate. For each and every gate the address will be allocated. The ladder program that where written in RSlogic 500 should be downloaded and switch it to run mode. Close the RSlogic and execute the project that was done in winlog Pro software project manager. Thus, the program and the logic were tested and the results are achieved successfully without any error.

References:

• Referred notes by J.G.Pierce.
• http://www.sielcosistemi.com/en/products/winlog_scada_hmi/