Total 4731 registered members

PowerLogic System lets you optimise the cost, quality and reliability of an electrical installation. It combines communicating devices with power monitoring software operating under Windows. PowerLogic System provides information on the entire electrical installation.

It offers a wide range of possibilities and can carry out a number of tasks including:
- alarm processing
- automatic tasks (e.g. automatic reports)
- precision instrumentation
- power quality and disturbance measurements
- data transfer
- etc.

PowerLogic System can be used for all electrical distribution systems. It creates a network of communicating devices connected to one or more supervision stations.

PowerLogic System is made up of three main parts:

  • communicating devices
  • communication interfaces
  • SMS software.

The products listed below are part of the PowerLogic System:

  • Circuit Monitor
  • Power Meter
  • low-voltage circuit breakers
  • Digipact DC150 interfaces
  • Sepam protection relays
  • Vigilohm System
  • and all third-party devices using the Modbus protocol (specific configuration is required).
PLC-Based Monitoring Control System

PLC-Based Monitoring Control System

With the rapidly changes on industries and information technologies in recent years, some traditional bulk electronic appliances have to be monitored for a long time. All of their control devices such as communication interfaces gradually enter the Intemet information era. The control of all equipment has been performed through the use of computers.

Most equipment uses PLC to connect with computers to monitor each load and electricity consuming devices. Programmable Logic Controllers (PLC) are widely used in industrial control because they are inexpensive, easy to install and very flexible in applications. A PLC interacts with the external world through its inputs and outputs.

PLC as a System Controller

Programmable logic controllers are modular, industrially hardened computers which perform control functions through modular input and output (I/O) modules. The modularity of PLC allows the user to combine generic I/O modules with a suitable controller to form a control system specific to his is most simply understood needs. The operation of a controller by envisioning that it repeatedly performs three steps:

  1. Reads inputs from input modules
  2. Solves preprogrammed control logic
  3. Generates outputs to output modules based on the control logic solutions. Input devices and output devices of the process are connected to the PLC and the control program is entered into the PLC memory (Fig.1).
Fig. 1. Control Action of a PLC

Fig. 1. Control Action of a PLC

In our application, it controls through analog and digital inputs and outputs the varying load-constant speed operation of an induction motor.

Also, the PLC continuously monitors the inputs and activates the outputs according to the control program. This PLC system is of modular type composed of specific hardware building blocks (modules), which plug directly into a proprietary bus: a central processor unit (CPU), a power supply unit, input-output modules I/O and a program terminal.

Such a modular approach has the advantage that the initial configuration can be expanded for other future applications such as multi machine systems or computer linking [2].

Control System of Induction Motor

The software models generated in the Software Requirements Analysis phase of the development project are refined and embellished in the design phase of the project. This phase involves making implementation decisions such as the interfacing between different software modules, the break down of software across multiple processors, assigning inputs and outputs to I/O cards, etc. PLC software, once written must be easy and intuitive to follow.

PLCs are an integrated part of the domain system, advances in the technology of the system will effect the requirements of the PLC software. PLC software must therefore be maintainable and extensible [18].

Fig. 2. Experimental setup

Fig. 2. Experimental setup

In Fig. 2, the block diagram of the experimental system is illustrated. The following configurations can be obtained from this setup.

  1. A closed-loop control system for constant speed operation, configured with speed feedback. The induction motor drives a variable load, is fed by an inverter and the PLC controls the inverter output.
  2. An open-loop control system for variable speed and variable frequency operation. The induction motor drives a variable load and is fed by control mode. The PLC is an inverter in constant in activated.
  3. The standard variable speed operation. The induction motor drives a variable load and is fed by a constant voltage-constant frequency standard three-phase supply.

The open-loop configuration (2.) can be obtained from the closed-loop configuration (1.) by removing the speed feedback. On the other hand, operation c) results if the entire control system is bypassed. [6-7] PLC’s programming is based on the logic demands of input devices and the programs implemented are predominantly logical rather than numerical computational algorithms. Most of the programmed operations work on a straightforward two-state “on or off” basis and these alternate possibilities correspond to “true or false” (logical form) and“ 1 or 0” (binary form), respectively. Thus, PLCs offer a flexible programmable alternative to electrical circuit relay-based control systems built using analog devices.

The programming method used is the ladder diagram method. The PLC system provides a design environment in the form of software tools running on a host computer terminal which allows ladder diagrams to be developed, verified, tested, and diagnosed. First, the high-level program is written in ladder diagrams. Then, the ladder diagram is converted into binary instruction codes so that they can be stored in random-access memory (RAM) or erasable programmable read-only memory (EPROM). Each successive instruction is decoded and executed by the CPU. The function of the CPU is to control the operation of memory and I/O devices and to process data according to the program. Each input and output connection point on a PLC has an address used to identify the I/O bit. The method for the direct representation of data associated with the inputs, outputs, and memory is based on the fact that the PLC memory is organized into three regions: input image memory (I), output image memory (Q), and internal memory (M).

Fig.3. Flowchart of the main program

Fig.3. Flowchart of the main program

Any memory location is referenced directly using %I, %Q, and %M (Table III). The PLC program uses a cyclic scan in the main program loop such that periodic checks are made to the input variables (Fig.3). The program loop starts by scanning the inputs to the system and storing their states in fixed memory locations (input image memory I).

The ladder program is then executed rung-by-rung. Scanning the program and solving the logic of the various ladder rungs determine the output states. The updated output states are stored in fixed memory locations (output image memory Q). The output values held in memory are then used to set and reset the physical outputs of the PLC simultaneously at the end of the program scan. For the given PLC, the time taken to complete one cycle or the scan time is 0, 18 ms/K (for 1000 steps) and with a maximum program capacity of 1000 steps.

The development system comprises a host computer (PC) connected via an RS232 port to the target PLC. The host computer provides the software environment to perform file editing, storage, printing, and program operation monitoring.

The process of developing the program to run on the PLC consists of: using an editor to draw the source ladder program, converting the source program to binary object code which will run on the PLC’ s microprocessor and downloading the object code from the PC to the PLC system via the serial communication port.

The PLC system is online when it is in active control of the machine and monitors any data to check for correct operation.

Table 1. Induction Motor Technical Specifications

Table 1. Induction Motor Technical Specifications


Table 2. Inverter Technical Specifications

Table 2. Inverter Technical Specifications


Table 3. PLC Configuration

Table 3. PLC Configuration


As a microprocessor-based system, the PLC system hardware is designed and built up with the following modules [7]:

  • Central processor unit (CPU)
  • Discrete output module (DOM)
  • Discrete input module (DIM)
  • Analog outputs module (AOM)
  • Analog inputs module (AIM)
  • Power supply
Fig. 4. Flowchart of speed control software

Fig. 4. Flowchart of speed control software

In Fig.4, the flowchart of the speed control software is illustrated. The software regulates the speed and monitors the constant speed control regardless of torque variation. The inverter being the power supply for the motor executes this while, at the same time, it is controlled by PLC’ s software. The inverter alone can not keep the speed constant without the control loop with feedback and PLC. From the control panel, the operator selects the speed set point nsp and forward/backward direction of rotation. Then, by pushing the manual start pushbutton, the motor begins the rotation. If the stop button is pushed, then the rotation stops.

The corresponding input signals are interfaced to the DIM and the output signals to the DOM. The AIM receives the trip signal from the stator current sensor, the speed feedback signal from the tacho-generator, and the signal from the control panel. In this way, the PLC reads the requested speed and the actual speed of the motor. The difference between the requested speed by the operator and the actual speed of the motor gives the error signal. If the error signal is not zero, but positive or negative, then the PLC according to the computations carried out by the CPU decreases or increases the V/f of the inverter and, as a result, the speed of the motor is corrected.

The implemented control is of proportional and integral (PI) type (i.e., the error signal is multiplied by gain Kp, integrated and added to the requested speed). As a result, the control signal is sent to the DOM and connected to the digital input of the inverter to control V/f variations. At the beginning, the operator selects the gain Kp, by using a rotary resistor mounted on the control panel (gain adjust) and the AIM receives its voltage drop as controller gain signal (0–10 V). The requested speed nsp is selected using a rotary resistor and the AIM reads this signal. Its value is sent to the AOM and displayed at the control panel (speed set point display).

Fig. 5. Flowchart of monitor and protection Software

Fig. 5. Flowchart of monitor and protection Software

Another display of the control panel shows the actual speed computed from the speed feedback signal. In Fig. 5, the flowchart of this software is shown.

During motor operation, it is not possible to reverse its direction of rotation by changing the switch position. Before direction reversal, the stop button must be pushed. For motor protection against overloading currents during starting and loading, the following commands were programmed into the software.

1. Forward/backward signal is input to DIM

2. Speed set point signal nsp, the stator current IS and the speed feedback signal are input to AIM.

3. At no load, Is ≤ 2,5 A, if the speed set point is lower than 20% or nsp< 300 r/min, the motor will not start.

4. At an increased load over 3,2 Nm (40% of rated torque), Is ≥ ,3 A and a speed set point lower than 40% or nsp< 600 r/min, the motor will not start.

5. If the load is increased more than 8,0Nm (rated torque) Is ≥ 4 A and if the speed set point exceeds 100% or nsp≥ 1500 r/min, the motor enters the cut off procedure.

6. In all other situations, the motor enters in the speed control mode and the speed control software is executed as described in Subsection A.

In Fig. 6, the flowchart of this software is shown.

Fig. 6. Flowchart of cutoff/restart motor software

Fig. 6. Flowchart of cutoff/restart motor software

  • In overloading situations, the motor is cut off and the trip lamp (yellow) is lit. The operator must release the thermal relays and then must turn off the trip lamp by pushing trip or stop button. The thermal relays are set to the motor rated current 4 A. Following this, the motor can be started again.
  • The motor can be cut off by the operator pushing the stop button: the display of the actual speed is set to zero, the start lamp (green) turns off, and the stop lamp (red) turns on and remains lit for 3 s.
  • The load must be disconnected immediately after the motor cuts off and before the drive system is restarted. The motor will not start before 3 s after cutoff even if the start button is pushed.


The system was tested during operation with varying loads including tests on induction motor speed control performance and tests for trip situations. The PLC monitors the motor operation and correlates the parameters according to the software. At the beginning, for reference purposes, the performance of induction motor supplied from a standard 380V, 50-Hz network was measured. Then, the experimental control system was operated between no load and full load (8, 0 Nm) in the two different modes described above:

  1. Induction motor fed by the inverter and with PLC control
  2. Induction motor fed by the inverter
Fig. 7. Experimental speed torque characteristics with PLC and inverter

Fig. 7. Experimental speed torque characteristics with PLC and inverter

The range of load torque and of speed corresponds to the design of the PLC hardware and software as described in the previous sections. The speed versus torque characteristics were studied in the range 500–1500 r/min and are illustrated in Fig. 7. The results show that configuration b) operates with varying speedvarying load torque characteristics for different speed set points nsp.

Configuration (1.) operates with constantspeed-varying load torque characteristics in the speed range 0–1400 r/min and 0–100% loads. However, in the range of speeds higher than 1400 r/min and loads higher than 70%, the system operates with varying-speedvarying-load and the constant speed was not possible to be kept. Thus, for nsp ≥ 1400 r/min both con-figurations (1.) and (2.) have a similar torque-speed response. This fact shows that PI control for constant speed as implemented by the software with PLC is effective at speeds lower than 93% of the synchronous[4-7].

Fig. 8. Efficiency of controlled system

Fig. 8. Efficiency of controlled system

The efficiency for different values of nsp was also studied. As depicted in Fig. 8, the results show that configuration (1.) in all cases has a higher efficiency than configuration (2.). Also, at operation with loads higher than 70%, the normalized efficiency is η(pu)> 1, meaning that the obtained efficiency with PLC control is higher than the efficiency of induction motor operated from the standard 380-V, 50-Hz network without the control of PLC and without the inverter.

According to this figure, the efficiency of PLC-controlled system is increased up to 10–12% compared to the standard motor operation. From a theoretical point of view, if we neglect magnetizing current, an approximate value for the efficiency is


where is the slip and Rs and Rr are the stator and rotor winding resistances, respectively. As can be seen from Fig. 7, the PLC controlled system a) works with very low slip values, almost zero. In all speed and load torque conditions, the configuration (1.) has a smaller slip than configuration (2.), thus the higher values of efficiency can be justified and especially at high speeds and frequencies. At lower frequencies, the magnetic flux increases and, thus, there is an increase in magnetizing current resulting in increased losses. This system presents a similar dynamic response as the closed-loop system with V/f speed control. Its transient performance is limited due to oscillations on torque and this behavior restricts the application of this system to processes that only require slow speed variation.


Successful experimental results were obtained from the previously described scheme indicating that the PLC can be used in automated systems with an induction motor.

The monitoring control system of the induction motor driven by inverter and controlled by PLC proves its high accuracy in speed regulation at constant-speedvariable-load operation. The effectiveness of the PLC-based control software is satisfactory up to 96% of the synchronous speed. The obtained efficiency by using PLC control is increased as compared to the open-loop configuration of the induction motor fed by an inverter. Specifically, at high speeds and loads, the efficiency of PLC-controlled system is increased up to 10–12% as compared to the configuration of the induction motor supplied from a standard network.

Despite the simplicity of the speed control method used, this system presents:

  • constant speed for changes in load torque
  • full torque available over a wider speed range
  • very good accuracy in closed-loop speed control scheme
  • higher efficiency;
  • overload protection

Thus, the PLC proved to be a versatile and efficient control tool in industrial electric drives applications.

Marmara University, Technical Education Faculty, Department of Electricity Education
Goztepe, 34722 Istanbul, TURKEY.,


Related articles

MOXA | Video Surveillance in Power Substations

MOXA | Video Surveillance in Power Substations

Power substations play a crucial role in delivering electricity to consumers by converting transmission voltage to the lower voltage used in homes and businesses. Since power plants are often located far from the population centers they serve, electricity needs to be transmitted across long distances at a higher voltage.

Power lines deliver electricity from the plant to the power substations where it is converted before being distributed to the local community. It is therefore imperative that power substations are constantly monitored for safety and maintenance as they are often located near or in a populated area. This white paper explains the benefits of real-time video monitoring and IP video technology, as well as factors to consider in deploying an optimal IP video surveillance system for a power substation.

Video Surveillance Benefits

Since power substations are widely distributed and unmanned, remote monitoring is extremely crucial. Real-time video surveillance of power substations offers automatic monitoring and control capabilities in addition to enhancing remote monitoring applications with visual management. These capabilities not only save management costs for manpower, but also realize complete network automation.

Supervisory Control and Data Acquisition (SCADA) systems, which are already deployed in power substations to provide data about the system’s status, can be easily integrated with video surveillance technology. By installing a real-time video monitoring system at power substations, system administrators are able to receive visual data to complement the raw SCADA data. Real-time video monitoring can help ensure normal operations for power equipment, protect against intrusion and tampering by unauthorized personnel, and prevent accidents. For example, intruders, physical obstructions, or smoke indicating a fire can be seen via video so engineers no longer need to visit the site in-person each time to diagnose an anomaly, saving both time and costs.

Remote video surveillance systems can play an important role in monitoring equipment, detecting intruders, and responding to emergency situations. For example, video surveillance can be used to monitor the appearance of the power transformer and relay, fueling and flammable equipment, and the status of the isolation switch. Video surveillance can also monitor the security situation inside and outside the substation by detecting intruders through sound and visual monitoring. In addition, video surveillance can be integrated with the alarm system and RTU (remote terminal unit) over a SCADA system to provide real-time visual information to prevent accidents and assist emergency response personnel in the event of a fire.

Why IP Video?

In the past, video surveillance systems such as CCTV networks relied upon analog video cameras. Due to advances in video digitization and compression technologies, high quality digital video images can now be sent over Ethernet TCP/IP networks. By using such devices, system integrators can easily integrate video surveillance applications into their SCADA system. As a result, Internet Protocol (IP) video technology is the current trend in video surveillance systems. The benefits of IP video surveillance include:

One Network - Using the existing IP network saves cabling costs and increases installation flexibility, especially for widely distributed substations. Ethernet TCP/IP networks can accommodate a variety of I/O monitoring and control devices in addition to transmitting data, video, voice, and even power (PoE) over a single network.

One System - Integration with SCADA or alarm systems (such as fire, intrusion, etc.) increases monitoring efficiency and creates an event-driven video surveillance system. This means the video images can be displayed and recorded and real-time responses can be received when an event or alarm occurs.

Constructing an Optimal IP Video Surveillance System

Given the critical role played by power substations in our daily lives, it is important for the IP video solution to be well-designed to ensure that the video surveillance system works properly. System integrators should consider factors such as applicability, reliability, integration, and user-friendliness in order to construct an optimal IP video surveillance system.

Applicability – System integrators need to consider video requirements such as image viewing, recording, and analysis, as well as interoperability with other systems (such as SCADA, Access Control, etc.) when deploying an IP video surveillance system. They also need to know how many cameras are required for the system and whether IP cameras or video encoders are suitable for the application. Network transmission factors such as bandwidth, multicast, and IGMP requirements, and whether the project requires a single network or separate networks for data and video are also important. Central management concerns, including system resources (PCs, servers, cost, etc.), software requirements (pure video or video integrated with another system), storage capability and database management, and whether or not a decoder is required, should also be considered.

Reliability - Since video monitoring is used to ensure safety and security in remote and disperse locations, reliability is a key factor in designing an optimal IP video surveillance system. Factors for reliability include surge protection and fiber transmission to reduce electromagnetic interference. Redundancy, high MTBF (meantime between failures) and IP protection are also important factors to consider for optimal reliability.

Integration - System integrators should consider integrating video surveillance into the central management system, as well as other systems, including SCADA/HMI, remote monitoring, and access control. This not only reduces cabling and network installation costs, but also makes central management and control easier to handle for system administrators. Interoperation with other devices for event-driven video monitoring is another benefit. For example, the system can begin recording video once a card reader or sensor is activated.

User-friendliness - IP video involves new applications and technologies that power system administrators need to learn. For this reason, it is recommended that system integrators choose ready-to-use hardware and software solutions to reduce the time needed to set up an IP video surveillance system. Not only does this simplify the system integrator’s task, but it will also be easier for system administrators to learn and use.

Video Surveillance in Power Substations

Video Surveillance in Power Substations

VPort Solutions

Moxa’s VPort industrial video networking solutions include video encoders and decoders, IP cameras, and IP video surveillance software designed for mission-critical video surveillance applications. Since most mission-critical application environments are demanding, the rugged design features of Moxa’s VPort solutions are particularly suitable for these kinds of applications.

Video servers – Digital video images require large data files, so video compression (reducing the quantity of data used to represent video images) is required for transmission and storage. Video servers include encoders and decoders. Encoders are used to convert analog video images from cameras into an easy to transfer digital format such as MJPEG or MPEG4. Decoders are used to convert images from compressed formats (MJPEG or MPEG4) back into analog for use with legacy monitors or displays.

IP cameras – IP cameras bypass the need for video encoders because the images are automatically encoded into a digital format (MJPEG or MPEG4) by the camera itself, and are easily transferred via Ethernet/Internet. Moxa’s VPort series of IP camera offers a wide operating temperature range of -40 to 50°C without the need for a fan or heater, IP66-rating for rain and dust protection, one camera lens for both day and night use, up to 30 frames per second at 720 x 480 resolution, and direct-wired power input and PoE (power over Ethernet) for power redundancy. Moxa’s industrial-grade video servers offer 12/24 VDC or 24 VAC redundant power inputs, DIN-Rail mounting and panel mounting accessories, IP30 protection, -40 to 75°C operating temperature range for T models, and RJ45 or fiber optic Ethernet ports.

Software – Moxa’s SoftDVR Surveillance Software, which includes SoftDVR Lite (4-ch) and SoftDVR Pro (16-ch), is designed for IP-based video surveillance systems. The client/server-based network infrastructure makes it easy to build a user-friendly video surveillance system. SoftDVR offers multi-screen viewing, event-driven recording, easy to use search and playback, data storage to network hard disks, scheduling feature for recording and alarm activation, and remote access by web browser.

SDK – Most video surveillance systems require customized video management functions, or must be integrated with other applications such as SCADA, access control systems, and fire alarms. For this reason, a user-friendly SDK (software development kit) is a good tool to have available for building customized video management systems. Moxa’s VPort SDK, which includes CGI Commands, ActiveX, and a C library, is available free of charge to system integrators and third-party software developers. Learning to use the Moxa VPort SDK is easy, and detailed documentation and sample code is provided for quick reference.


Transmitting video, voice, and data simultaneously over Ethernet/Internet is becoming a standard feature due to the ever-increasing popularity of IP networks. Versatile and advanced video digitizing and compression technologies, such as MJPEG and MPEG4, are also making it possible to migrate analog CCTV surveillance systems to IP-based platforms.

Power substations play an instrumental role in delivering electricity from power plants to end-users, so managing and ensuring the safety and security of these installations through an optimal video surveillance system is imperative. Since power substations are unmanned and widely distributed installations, video surveillance grants system administrators visual management capabilities in addition to data management provided by existing central control systems that only provide raw quantitative data. The versatility of IP video technology and its ability to be integrated with existing central control systems make it an attractive option for remote video monitoring in power substation applications.


SOURCE: MOXA, Harry Hsiao, Product Manager at Moxa;;


Related articles

Energy management control center
Energy management control center

Energy management is the process of monitoring, coordinating, and controlling the generation, transmission, and distribution of electrical energy. The physical plant to be managed includes generating plants that produce energy fed through transformers to the high-voltage transmission network, interconnecting generating plants, and load centers. Transmission lines terminate at substations that perform switching, voltage transformation, measurement, and control. Substations at load centers transform to subtransmission and distribution levels. These lower-voltage circuits typically operate radially, i.e., no normally closed paths between substations through subtransmission or distribution circuits. (Underground cable networks in large cities are an exception.)

Since transmission systems provide negligible energy storage, supply and demand must be balanced by either generation or load. Production is controlled by turbine governors at generating plants, and automatic generation control is performed by control center computers remote from generating plants. Load management, sometimes called demand-side management, extends remote supervision and control to subtransmission and distribution circuits, including control of residential, commercial, and industrial loads.

Events such as lightning strikes, short circuits, equipment failure, or accidents may cause a system fault. Protective relays actuate rapid, local control through operation of circuit breakers before operators can respond. The goal is to maximize safety, minimize damage, and continue to supply load with the least inconvenience to customers. Data acquisition provides operators and computer control systems with status and measurement information needed to supervise overall operations. Security control analyzes the consequences of faults to establish operating conditions that are both robust and economical.

Energy management is performed at control centers (see picture below), typically called system control centers, by computer systems called energy management systems (EMS). Data acquisition and remote control is performed by computer systems called supervisory control and data acquisition (SCADA) systems. These latter systems may be installed at a variety of sites including system control centers. An EMS typically includes a SCADA ‘‘front-end’’ through which it communicates with generating plants, substations, and other remote devices.

Picture below illustrates the applications layer of modern EMS as well as the underlying layers on which it is built: the operating system, a database manager, and a utilities=services layer.

Layers of a modern EMS

Layers of a modern EMS (Energy management systems)

SCADA – Supervisory control and data acquisition

A SCADA system consists of a master station that communicates with remote terminal units (RTUs) for the purpose of allowing operators to observe and control physical plants.

Generating plants and transmission substations certainly justify RTUs, and their installation is becoming more common in distribution substations as costs decrease. RTUs transmit device status and measurements to, and receive control commands and setpoint data from, the master station.

Communication is generally via dedicated circuits operating in the range of 600 to 4800 bits=s with the RTU responding to periodic requests initiated from the master station (polling) every 2 to 10 s, depending on the criticality of the data.
The traditional functions of SCADA systems are summarized:

  • Data acquisition: Provides telemetered measurements and status information to operator.
  • Supervisory control: Allows operator to remotely control devices, e.g., open and close circuit breakers. A ‘‘select before operate’’ procedure is used for greater safety.
  • Tagging: Identifies a device as subject to specific operating restrictions and prevents unauthorized operation.
  • Alarms: Inform operator of unplanned events and undesirable operating conditions. Alarms are sorted by criticality, area of responsibility, and chronology. Acknowledgment may be required.
  • Logging: Logs all operator entry, all alarms, and selected information.
  • Load shed: Provides both automatic and operator-initiated tripping of load in response to system emergencies.
  • Trending: Plots measurements on selected time scales.

Since the master station is critical to power system operations, its functions are generally distributed among several computer systems depending on specific design. A dual computer system configured in primary and standby modes is most common. SCADA functions are listed below without stating which computer has specific responsibility.

  • Manage communication circuit configuration
  • Downline load RTU files
  • Maintain scan tables and perform polling
  • Check and correct message errors
  • Convert to engineering units
  • Detect status and measurement changes
  • Monitor abnormal and out-of-limit conditions
  • Log and time-tag sequence of events
  • Detect and annunciate alarms
  • Respond to operator requests to:
    • Display information
    • Enter data
    • Execute control action
    • Acknowledge alarms
  • Transmit control action to RTUs
  • Inhibit unauthorized actions
  • Maintain historical files
  • Log events and prepare reports
  • Perform load shedding


Related articles