Remote Terminal Units (RTUs) collect data automatically and connect directly to sensors, meters, loggers or process equipment. They serve as slave units to supervisory controllers or supervisory control and data acquisition (SCADA) masters. Remote terminal units are located near the monitored process and transfer data to the controller unit on command. They often include integral software, data logging capabilities, a real-time clock (RTC) or totalizer, and a battery backup
Monitoring and maintenance of cathodic protection services is done by periodic close interval surveys which are conducted in the test stations. It is done by measuring structure-to-electrolyte potentials with the use of suitable half cell or maximum input voltmeter. Cathodic protection rectifiers are adjusted so that the protective elements are maintained at desired negative levels as required by the project details. Remote Terminal Unit (RTU) is used to monitor cathodic protection rectifiers that are displayed
at test stations. Yet, there are other communication equipments available for monitoring pipe to soil elements used during aerial survey with the use of an airplane or a helicopter.
Remote Terminal Unit (RTU) monitors the field digital and analog parameters and transmits all the data to the Central Monitoring System (CMS). This microprocessor can be interfaces with the central station with different communication media. RTU can support standard protocols to interface any third party software. In some control applications, RTU’s drive high current capacity relays to a digital output board to switch power on and off to devices in the field.
Modern RTU’s are usually capable of executing simple programs autonomously without involving the host computers of the Supervisory Control and Data Acquisition System (SCDAS) to simplify deployment and to provide redundancy for safety reasons.
In a modern water management system, RTU will typically have code to modify its behavior when physical override switches on the RTU are toggled during maintenance by maintenance personnel. This is done for safety reasons.
Remote Terminal Unit (RTU) is applied in many ways, such as:
- Oil and Gas remote instrumentation monitoring, (offshore platforms, onshore oil wells).
- Networks of remote pump stations (wastewater collection, or for water supply).
- Hydro-graphic monitoring and control, (water supply, reservoirs, sewerage systems).
- Environmental monitoring systems (pollution, air quality, emissions monitoring).
- Mine site monitoring applications.
- Protection supervision and data logging of Power transmission network
- Air traffic equipment such as navigation aids (DVOR, DME, ILS and GP)
- Outdoor warning sirens, in both controlling them, and sending back data for verification of activation, anything broken, etc. American Signal offers this as CompuLert, and Federal Signal offers it, but isn’t trademarked. Both can be setup to use DTMF or FSK for the data transport layer.
