Brief introduction of Rosemount 644 temperature transmitter. 
644 Top junction box and guide rail installation temperature transmitter for high precision and reliability in control applications. 
The Rosemount 644 temperature transmitter is an ideal product for critical applications (for a variety of process environments). 
It provides high-precision measurement for all kinds of equipment and fully demonstrates the reliability of the product. 
The Rosemount 644 can be ordered at the same time with the 4-20mA/HART or all-digital Foundation fieldbus protocol. 
Each unit can be configured to accommodate the input of various types of sensors: thermal resistance, thermocouple, millivolt meter or ohmmeter. 
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Digital field equipment provides power. 
The use of HART or fieldbus communication devices can ensure the good play of high performance and advanced diagnostic technology. 
Thus, these transmitters transmit the information to the AMS intelligent device management system. 
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The transmitter matches the sensor. 
For intrinsically safe devices, only one safety grid is needed for a number of 848T temperature transmitters to input the temperature impedance curve of the designated RTD sensor into the 644 transmitter, and then the transmitter and the sensor can be perfectly matched, avoiding the interchangeability error of the sensor and improving the accuracy by 75%. 
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Integrated LCD display. 
Temperature measurement and diagnostic functions can provide immediate and accurate changes in process conditions. 
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Reliable transmitter performance. 
The 644HART transmitter complies with the NAMUR NE21 standard and ensures best-in-class transmitter performance even in extremely demanding electromagnetic compatibility environments. 
In addition, the 644HART transmitter complies with NAMUR NE43 and NE89 recommendations. 
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Installation flexibility. 
The DIN A top junction box mounting transmitter is suitable for a variety of remote transmitter mounting housings and can be integrated or remotely mounted on a single sensor. 
Compact guideway mounting is ideal for DIN guideway installation in narrow spaces in dense control rooms. 
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Rosemount 644 temperature transmitter details: 
Rosemount 644H temperature transmitter and Rosemount 644R intelligent temperature transmitter are an extension of the Rosemount Rosemount temperature transmitter instrument family, which can receive 2 -, 3-and 4-wire thermal resistors, thermocouples, and resistive and millivolt inputs. 
Each transmitter is characterized by ambient temperature in the factory to reduce the measurement error in the whole working temperature range. 
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The Rosemount 644H temperature transmitter can be installed in a connecting housing on the sensor to form an integrated temperature assembly, or in a junction box away from the sensor installation, or using an optional mounting assembly (00644-5301-0010), install the Rosemount 644H temperature transmitter on the guideway. 
Rosemount 644R temperature transmitters can be mounted directly on walls or DIN rails. 
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The Rosemount 644 temperature transmitter offers excellent performance and reliability compared to the sensor's direct wiring. The optional WAGO spring clamp terminal provides an anti-vibration connection for situations where fastening is not required, greatly reducing wire and labor costs, and advanced diagnostic functions can reduce the number of on-site maintenance. 
Ordering complete temperature transmitters and temperature sensor components simplifies installation, specifications and ordering, thereby reducing costs. 
Excellent accuracy, stability and anti-radio frequency interference ability to reduce process variability. 
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Excellent performance and reliability of Rosemount 644 temperature transmitter. 
The transmitter-sensor comparison function can improve the measurement accuracy of the whole system. 
Temperature correction circuit to reduce the influence of ambient temperature. 
Independent alarm circuit for fault detection of electronic boards and sensors. 
The performance index is at least 3 σ. 
Accuracy: ±0.15C (±0.27oF), Pt100 thermal resistance. 
Stability: ±0.1% reading or ±0.1 ℃, whichever is the greater, 12 months, thermal resistance and thermocouple input. 
Within the range of the sensor, the range setting is unlimited. 
The optional WAGO spring clamp terminal provides an anti-vibration connection for situations where fastening is not required. 
Maintainability. 
Compatibility with HART375 handlers, HART475 handlers based on HART protocol and PC-based AMS device management system. 
Improve the efficiency, quality and productivity of the process. 
Main index. 
Simulation accuracy: ±0.03% range. 
Digital accuracy: ±0.15C (±0.27F), Pt100 thermal resistance. 
Influence of ambient temperature: 0.003 ℃ / 0.003 ℃, Pt100. 
Stability: the error is ±0.1% in one year. 
Input: thermocouple, Mv,ohm. 
Output: 4-20 Ma, using HART communication protocol. 
Supply voltage: 12.0 to 42.4 volts