SCADA is an acronym for Supervisory Control and Data Acquisition. Its basic purpose is to remotely monitor various processes, gather real-time data and then analyze it. The development and use of SCADA can be tracked back to the 1960's, when simple input/output devices were used to remotely monitor operations in industrial applications. With advancements in technology, SCADA systems are now developed using high-end software, high-speed microprocessors, wireless technology, etc.
Components of the SCADA system
SCADA systems typically are made of four components:
- Master SCADA Unit - This is heart of the system and is centrally located under the operator's control.
- Remote SCADA Unit - This unit is installed from where the process is actually monitored. It gathers required data about the process and sends it to the master unit.
- Communication Mode - This unit transmits signals/data between the master unit and the remote unit. Communication mode can be a cable, wireless media, geo-synchronous satellite, etc.
- SCADA Software - The software is an interface between the operator and the units. It allows the operator to visualize and control the functions of the process.
Example of a SCADA system
To understand the operation of industrial SCADA, consider the following example: Several pipes fill up water tanks at some remote location, where human supervision may not be possible. Also it is difficult to monitor several pipes simultaneously. SCADA systems are installed in such instances. When a particular tank reaches its overflow level, the remote unit senses it and sends a signal to the master unit. An alarm is triggered at the master unit station and the operator is made aware of the condition. The operator can visualize the situation using the SCADA software and can appropriately regulate the valve of the required pipe.
As already explained, wireless media can also be a communication medium for the master unit and the remote unit. Systems using this type of media are termed "wireless SCADA systems." A few examples of wireless media are explained below.
- Spread Spectrum Radio - The frequency band for this is 900 MHz to 5.8GHz and is free for general pubic use. Spread spectrum radio modems are used to ensure efficient network communication.
- Microwave Radio - In this case signals are transmitted at high frequencies using parabolic dishes installed on towers or on the tops of buildings. However, one disadvantage of this communication is that transmission may get interrupted due to misalignment and/or atmospheric conditions.
- VHF/UHF Radio - This is an electromagnetic transmission with frequencies of 175MHz-450MGz-900MHz. Special antennas are required to receive these signals.
Benefits of a Wireless SCADA system
A perfectly designed wireless SCADA system offers the following benefits:
- Monitors in real time
- Minimizes the operational costs
- Provides direct information of system performance
- Improves system efficiency and performance
- Increases equipment life
- Reduces labor costs required for troubleshooting or servicing the equipment
- Automated report generation reduces errors in calculations and interpretations
- Uses advanced technologies
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