Remote terminal unit

Signal Transmission and Conditioning. A wide variety of physical and chemical phenomena are used to measure the many process variables required to characteri2e the state of a process. Because most processes are operated from a control house, these values must be available there. Hence, the measurements are usually transduced to an electronic form, most often 4 to 20 m A, and then transmitted to the control house or to a remote terminal unit and then to the control house (see Fig. 6). Wherever transmission of these signals takes place in twisted pairs, it is especially important that proper care is taken so that these measurement signals are not cormpted owing to ground currents, interference from other electrical equipment and... 

The central computer is called the master terminal unit, or MTU. The MTU has two main functions to periodically obtain data from RTUs/PLCs and to control remote devices through the operator station. The operator interfaces with the MTU using software called human machine interface (HMI). The remote computer is called the program logic controller (PLC) or remote terminal unit (RTU). The RTU activates a relay (or switch) that turns mechanical equipment on and off. The RTU also collects data from sensors. Sensors perform measurement, and actuators perform control. 

Automation equipment at the metering sites generate production volume information, indicate alarm and other equipment status, and provide some control capability. This equipment is connected to remote terminal units (RTU) at optimum points within the field by individual wire pairs of buried cable. The RTU s store the information generated and, on request from the computer, transmit it to the computer center by means of microwave or wireline. RTU s also receive messages from the computer for transmittal to appropriate equipment for execution. 

A remote terminal unit (RTU) capable of retaining volume and energy units in 15-minute increments for up to 72 hours. Also it must have the capability of two-way cormnunications with the host computer. 

Remote Terminal Units (RTU) are located in the field , i.e., they are scattered along the Cl. Both, sensors and actuators are attached to a designated remote terminal unit (RTU), either wired (e.g., through serial interface) or wireless (e.g., through ZigBee [30]). RTUs communicate with superordinate stations using IP encapsulated SCADA protocols. 

Control system PLCs/remote terminal units (RTUs)... 

Modem supervisory control and data acquisition (SCADA) in midstream. PLCs, programmable logic controllers RTU, remote terminal unit. 

Remote terminal units (RTUs) connecting to sensors in the process, converting sensor signals to digital data and sending digital data to the supervisory system. 

Fig. 6. Impact of field bus on wiring costs, where A/D and D/A correspond to analogue-to-digital and digital-to-analogue converters, respectively LCU = local control unit and I/P = current-to-pressure transducer, (a) DCS without remote terminal rooms (b) DCS with remote terminal rooms and...

Induction terminal unit An air terminal assembly which by virtue of the configuration of the primary air inlet(s) within the unit can induce secondary air from the surrounding atmosphere before being discharged to the treated space. The tlow rate of the primary air may or may not be variable. The inlet aperture(s) for the secondary air may be fixed or adjustable by means of manual remote control. 

Fig. 10.15 Three-channel AAS coupled with a microcomputer for processing of data. H hollow-cathode sources C rotating sector B burner M monochromator units P detectors J beam chopper and start/reset unit I spectrometer control panel A analogue/digital converter K remote terminal V video monitors. (Reproduced from [43] with permission of Elsevier).

The structural unit of this subtype of polycyclic alkaloid is a 3-alkyl substituted pyridine, where remote terminal oxime, amine, methoxy amine, nitro, imine oxide or methoxy-oxime fuctionalities are characteristic in the monomeric forms. Polymeric pyridinium salts attached to a long linear carbonated chain through positions 1 and 3 are a substructural feature in a second subgroup of alkaloids. Related reduced dihydropyridinium salts have also been known since the discovery of haliclamine A and B. (See Tables 5 and 6 for C-NMR data). 

Gelatin filter sampler. The unit consists of a vacuum pump with an extension hose terminating in a filter holder that can be located remotely in the critical space. The filter consists of random fibers of gelatin capable of retaining airborne micro-organisms. After a specified exposure time, the filter is aseptically removed and dissolved in an appropriate diluent and then plated on an appropriate agar medium to establish its microbial content. 

Biometrics can be used in granting the remote access to the network. The scenario employs a common client-server network model, thus incorporating standard security mechanisms with biometric enhancements. The client terminal (see Figure 9) is a biometric-based host, equipped with the capturing device and the processing unit that measures the biometric trait and calculates the features vector (biometric template). The client capabilities may be understood in a wider sense, thus enabling the client to be equipped with sensors related to more than one biometric modality. The proposed access scenario enables to include the aliveness detection capability and the biometric replay attack prevention. To insert the necessary elements into the communication flow, capture-dependent parameters will be retrieved by the client terminal prior to the biometric trait measurement. 

Currently, remote I/O systems of several manufacturers are available for operation in zone 1 or Division 1. To a large extent, these systems are based upon the technology of intrinsic safety. The power supply only is designed according to another type of protection, e.g. flameproof enclosure - d A remote I/O suitable for hazardous areas may be an integration of input (I) and output (O) assembly units of automation systems and of Ex i-isolators of classic design. The installation may be made in a hazardous area and supersede the classic field distribution box (terminal box). Standardized fieldbus systems may be used for data transmission from/to the automation system. These remote I/O systems for hazardous areas are characterized as follows ... 

I had already bolted the alternator s control panel to the hydro unit, added terminals to its wires, and connected them to the appropriate terminals on the alternator. The only remaining job was to route the twisted wires (from the remote shunt) to the control panel and screw them down to the terminal strip inside. I added silicone sealant to seal the hole where the wires... 

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