I. Product Overview

The temperature transmitter is a kind of instrument that converts the temperature variable into a standardized output signal that can be transmitted. The function of the temperature transmission is mainly used for measuring and controlling the temperature parameters in the industrial process. Transducers with sensors are usually made up of two parts: sensors and signal converters. Sensors are mainly thermocouples or thermal resistors; signal converters are mainly composed of measuring units, signal processing and conversion units (because the industrial thermal resistance and thermocouple dividing tables are standardized, so the signal converters are also called transmitters as independent products). Some transducers have added display units, and some have field bus functions.

Two. Main features:
By adopting silicone rubber or epoxy resin sealing structure, it is shock resistant and moisture resistant, and is suitable for installation and use in the field.

The field is installed in the junction box of thermocouple and thermoelectric resistance, and directly outputs the output signals of 4-20mA and 0-10mA. In this way, the cost of the expensive compensation conductor is saved, and the anti-interference ability of the signal in the long distance transmission process is enhanced.

The thermocouple transmitter has the function of cold end automatic compensation, high accuracy, low power consumption, wide temperature range in use environment, stable and reliable operation.

Wide range of applications, that is, it can be integrated with the thermocouple and thermal resistance to install the on-site installation structure, or it can be used as a function module installed in the detection equipment and the instrument panel.

Three. Working principle

The thermocouple or thermistor sensor is converted to electrical signal by temperature, and then sent to the input network of transmitter. The network contains zeroing and thermocouple compensation. After zero adjustment, the signal is input to the operational amplifier to amplify the signal. The amplified signal is output by DC4-20mA current after the V/I converter is processed and processed, and the other way is displayed by the A/D converter after being processed. There are two kinds of linearization circuits for transmitters, all of which adopt feedback mode. The thermal resistance sensor is corrected by positive and negative method, and the thermocouple sensor is corrected by multi section broken line approximation. Integrated digital display temperature transmitter LCD display using two wire mode output.

Four. Technical parameters

1. input signal: thermocouple: K, E, J, B, S, T, N; thermal resistance: Pt100, Cu50, Cu100, (three wire, four wire system). The input signal of the intelligent temperature transmitter can be set by means of the PC or hand-held device.
2. output signal: output the DC4-20mA current signal in the range, linearly with the thermocouple or thermal resistance input signal or linearly with temperature.The intelligent temperature transmitter outputs DC4-20mA current signal superimposed with HART standard protocol communication signal simultaneously.
3. basic error: 0.5%FS; 0.2%FS; intelligent 0.2%FS;
4. wiring mode: two-wire system; three wire system;
5. display mode: four bit LCD display temperature, intelligent four bit LCD can be set through PC or manual operator to display the parameters of field temperature, sensor value, output current and percentage percentage.

6. working voltage: common type 12 35V DC; intelligent 12V 45V DC; rated working voltage is 24V DC;
7. allows load resistance: 500 ohms (24VDC power supply); limit load resistance R (max) =50 (Vmin-12), for example, when rated operating voltage 24V DC, load resistor can be selected within 0-600 ohms.

8. working environment:
A: ambient temperature -25 - 80 C (conventional)
-25 C 70 C (digital display)
B: the relative temperature is 5% 95%.
C: the mechanical vibration f is less than 50HZ, the amplitude is less than 0.15mm
D: no corrosive gas or similar environment.
9. temperature influence coefficient: Delta is less than 0.05%/ degrees.