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  • Publicado : 19 de febrero de 2012
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SMART TEMPERATURE TRANSMITTERS

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FEATURES

Single unit accepts signal from: - Standart RTDs and Thermocouples - Single ended or differential sensing - mV signals from radiation pyrometers, load cells, etc. - Ohm signals from position indicators, etc. Built-in thermocouples and RTDs linearization 0.02% basic accuracy Excellent long term stability due to auto-zero at the input circuitSignal isolation High EMI-RFI immunity Two wire, 4-20 mA output plus direct digital communication (HART Protocol) Remote configuration via Hand-Held Terminal or via PC On-line and off-line configuration Special 16-point sensor characterization Optional PID control function with programmable setpoint curve Explosion proof and weather proof lntrinsically safe

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DESCRIPTION

The SmarTT301 is a powerful and extremely versatile Smart temperature transmitter, which can be used with practically all relevant temperature sensors as well as with load cells, resistance position indicators, etc. The same unit can be used for different measuring ranges and many types of sensors such as various thermocouples and RTDs, mV or Ohm (see table on Functional Specifications). Hence, the plantcan be standardized using the TT301 in measurements where different types of conventional (analog) transmitters previously where necessary. This drastically reduces calibration and maintenance time, spare part requirements and training. It also allows the TT301 to be purchased before measurement and control parameters are known. Input/Output isolation with high RFI and EMI immunity are standardfeatures. The TT301 transmitter is suitable for direct field installation, being weather proof and explosion proof, as well as intrinsically safe, for use in hazardous areas. As a two-wire temperature transmitter the TT301 generates a 4-20 mA output signal proportional to the desired temperature range.

Together with the 4-20 mA signal on the same pair of wires, there is a digital signal forcommunication. With a Hand-Held Terminal and using digital communication the TT301 can be configured and reranged locally or remotely. The Hand-Held Terminal can be connected in any point of the 4-20 mA line. The TT301 can operate as a conventional analog transmitter. The user may choose not to use the digital communication capability if he so desires. A unique feature of the TT301 is the optional PIDcontrol capability. With one instruction via Hand-Held Terminal or the local adjustment, the transmitter start working as transmitter plus controller. The 4-20 mA is the output of a PID controller whose process variable is the measured temperature and the setpoint is adjusted by the operator or a configurable setpoint generator. The output signal can be connected to a final control element, as acontrol valve, while the digital part of the signal inform the process variable, output, the setpoint, and all other transmitter and PID parameters. The TT301 operates as shown on the block diagram.

Main Processor Assembly

SENSORS TC RTD OHM mV INPUT SIGNAL CONDITIONER A/D CONVERTER
ISOLATOR

ZERO/ SPAN LOCAL ADJUSTMENT

PROCESSING UNIT
RANGES SPECIAL FUNCTIONS PID (optional) OUTPUTCONTROL SERIAL COMMUNICATIONS HART PROTOCOL

D/A CONVERTER

INPUT/OUTPUT STAGE

+
4-20 mA

AMBIENT TEMPERATURE SENSOR

MODEM BELL 202

SIGNAL CONDITIONER

-

LCD Indicator Assembly
LCD DISPLAY CONTROLLER

DIGITAL DISPLAY

3

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CONFIGURATION AND ADJUSTMENT

CONF301 - CONFIGURATION SOFTWARE

The TT301 can be configured by a Hand-Held Terminal or PC (Personal Computer)using the software CONF301, together with a SMAR HI311 interface (HART/RS232C). The CONF301 is a configuration tool running under the application MS Windows operating system. Configuration, reranging, PID adjustment (optional), setpoint changing, etc. are performed by both the HandHeld Terminal and CONF301, when connected in parallel to any point of the 4-20 mA line. A single Hand-Held Terminal...
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