Capacitive intelligent transmitter 3051/1151

Capacitive intelligent transmitter is a pressure instrument with a microprocessor as its core, which adds communication and other functions to the structure of traditional capacitive transmitters. The communication controller or other host using the HART protocol can be used for bidirectional communication (reading, writing data, and diagnosis) with it in the control room, transmitter site, or anywhere connected to the control circuit.

In addition to the inherent characteristics of general capacitive transmitters, smart transmitters also have the following features:
The use of microprocessors increases the flexibility and functionality of smart transmitters.
Intelligent electronic components are composed of only one board, which has stronger advantages and higher reliability.
The range ratio is 10:1 or 100:1.
Wide range: 0-25Pa to 42MPa.
Adjust the zero point and range locally by pressing the button.
◆ Various existing 3051/1151 analog transmitters can be updated to smart transmitters.
◆ Compliant with the HART protocol, it can communicate bidirectionally with this smart meter using a HART communicator without interrupting the output signal.
◆ It has self diagnosis and remote diagnosis functions.
Equipped with EEPROM, not afraid of losing data due to power failure.

----The pressure signal measured by the sensitive component in the above figure is converted into a direct current signal proportional to the pressure through oscillation and demodulation. The A/D converter converts this current into a digital signal, and its value is used by the microprocessor to determine the input pressure value.
The microprocessor controls the operation of the transmitter. In addition, it also performs calculations such as sensor linearization, resetting measurement range, conversion of working units, damping, square root, sensor fine-tuning, as well as diagnosis and digital communication.
----The D/A converter converts the calibrated digital signal from the microprocessor into a 4-20mA analog signal and sends it to the output circuit. EEPROM stores all configuration, characterization, and digital fine-tuning data, which can be modified using transmitter software. The data is stored in EEPROM and remains intact even when powered off.
----The digital communication line provides a connection interface for the transmitter to external devices (control systems using HART protocol). This line detects the digital signal superimposed on the 4-20mA signal and transmits the required information through the loop.

(Reference conditions: no migration, silicone oil filling, and isolation membrane made of 316L stainless steel)
accuracyFor DP and GP transmitters, the range code 4-8 is ± 0.2% (range ratio within 10:1; 3051 transmitter can reach 0.075%), while for other transmitters and range ranges, it is ± 0.25%.

StabilityWithin twelve months, the accuracy of the transmitter shall not exceed.

Temperature influenceFor DP and GP transmitters with range codes of 4-9,0, the total error is less than ± 0.3% * large range limit, with a change of 10 ℃; For other transmitters and other ranges, the above error values will double.

Static pressure effect： DP class zero position error: For 14MPa, ± 0.25% * large range limit or ± 0.5% * large range limit (range code 3), correction is given by zero adjustment under pipeline pressure.

HP class zero position error: ± 2% * Large range limit, for 32MPa; Correct by zeroing under pipeline pressure.

span error± 0.25% input reading, every change of 7MPa.

vibration effect± 0.1% * large range value, 10-60Hz, S=0.07mm, 60-150Hz, g=9.8m/s2 in any direction

Power supply impactLess than 0.005% output range/V.

Electromagnetic radiation impact0.1% * large range value, accepted radiation frequency of 27-500MHz, test field strength of 3V/m.

Installation location impactWhen the working diaphragm is not vertical, a zero position error of no more than 0.24 kPa may occur, which can be eliminated by adjusting the zero position and has no effect on the range.

Structural materialsThe materials of parts that come into contact with the medium, such as pressure chambers, joints, relief valves, and isolation diaphragms, are listed in the selection table for various models

Electrical connectionThe transmitter housing has 2 M20 × 1.5 screw holes or NPT1/2 internal threads for connecting cable conduits, and there are wiring terminals and measuring gaskets inside the housing for testing. If connected to the communicator, it must be fixed on the measuring pad.

Using advanced integrated circuits and surface mount technology (SMT), the electronic components of the transmitter are composed of a single circuit board. The microprocessor of the transmitter controls the A/D and D/A conversion, and can also perform self diagnosis and achieve digital communication.
----During work, a digital pressure value is processed by a microprocessor and stored as a digital value to ensure precise correction and conversion of engineering units. In addition, microprocessors can also perform linearization, range ratio, damping time, and other functions of sensors. EEPROM stores all configuration, characterization, and digital fine-tuning parameters, and the memory is non-volatile. Therefore, even if the power is cut off, all stored data can still be preserved intact, enabling intelligent communication at any time.

SoftwareTest and configure the smart transmitter through a HART communicator. Alternatively, communication can be completed through any upper system that supports the HART communication protocol. The HART protocol uses the industry standard BELL202 frequency shift keying (FSK) technology to achieve communication by superimposing 1200Hz or 2200Hz digital signals on 4-20mA signals. The frequency signal does not cause any interference to the process signal of 4-20mA during communication.

Self diagnosisIntelligent transmitters can complete continuous self diagnosis. If a fault is detected in the transmitter, the output of the transmitter can be selected by the user to be greater than 22mA or less than 3.8mA, and any HART upper computer device can display the special information code for self diagnosis of the transmitter.

formatThe formatting function is used during transmitter initialization and maintenance of digital electronic components. The standard formatting menu provides two functions: characterization and digital fine-tuning.

CharacterizationAlthough smart transmitters are already characterized at the factory, users can still use this feature to make some simple updates to existing analog transmitters, converting them to smart models. Characteristic function: Adjust the electronic components of the 1151 intelligent capacitive transmitter to accurately reflect the output of the sensor.

Digital trimsThis function allows for digital calibration of the transmitter's characteristics to achieve the pressure standard value calibrated by the manufacturer.
Digital fine-tuning includes two independent operations:
① Sensor fine-tuning: It can adjust the reading of the digital process change to reflect the pressure input;
② Analog output adjustment: Make the digital current of the instrument consistent with the 4-20mA analog output current of the instrument.

Configuration
standard configurationUnless otherwise specified, the following configuration will be supplied:
Engineering unit - kPa; 4mA－0kPa； 20mA - upper range limit value; Output - Linear.
Software tags: Blank [Software label (8 characters), unless specified, it is blank]
Special configurationIn addition to standard configuration parameters, users can also specify additional data in the table below.