RTU (Remote Control Unit) basics

Industrial Automation
1

What is the RTU?

RTU, Remote Control Unit is an electronic device that is used in industrial control systems such as DCS and SCADA. It is a microprocessor-based device, works as a standalone data acquisition and control unit.

An RTU unit at the remote station acquire data from the devices and to transfer this data back to a central station. By sending signals to equipment the RTU can control equipment, such as opening or closing a valve or setting the speed of a pump. RTU can read and send both digital and analog data.

Architecture of RTU:

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In general the RTU design should aim to minimise power consumption and heat generation. It should be designed to work in a HV electrical installation by being of robust physical construction with immunity to electrical noise.

  • There is one centralized RTU unit and different RTU units at the field.

  • Centralized RTU design where all the I / O modules are housed in RTU panels and communicate with the main station through the communication port.

  • Distributed RTU design in which the I / O modules are housed in the respective Bay C & R panels. All these distributed I / O modules will be connected to a central processor for further communication with the master station. The tenderer will evaluate the requirement of RTU / SIC panels for such design and supply panels accordingly.

Functions of RTU:

As a minimum, the RTUs shall be capable of performing the following functions:

  • Collecting and processing the digital status inputs, analog inputs, accumulated values and transmitting to at least three master station(s).

  • Recieve and process data received from master RTU

  • Data transmission rates from 300 to 9600 baud for serial ports and 10/100 Mbps for TCP/IP Ethernet ports.

  • The RTU will have the ability to automatically start and initialize after restoring power after an interruption without the need for manual intervention. All restarts will be reported to the connected master station.

  • Acting as a data concentrator to acquire slave RTU data and exercise supervisory control in slave RTUs using the IEC 60870-5-101 and IEC 60870-5-104 protocols.

Applications of RTU:

  • Distributed processes have to be monitored and controlled,

  • Functions previously available at the higher control level are distributed or implemented on site.

  • Noise immunity is very important.

  • The communication backbone (fibre optic cable) can transfer such as operational Data (pressure, temperature, valve position) from the RTU, Voice over IP, Video Data

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