Thermocouple Measurements

Chapter 4 Features and Functions

Temperature Measurement Configuration

To connect a thermocouple to the module’s screw terminals, see page 21.

•The instrument supports the following thermocouple types: B, E, J, K, N, R, S, and T using ITS-90 software conversions. The default is a J-Type thermocouple.

•Thermocouple measurements require a reference junction temperature. For the reference junction temperature, you can use an internal measurement on the module, an external thermistor or RTD measurement, or a known fixed junction temperature.

•If you select an external reference, the instrument automatically reserves channel 01 on the multiplexer in the lowest slot as the reference channel (thermistor or RTD measurement). If you have more than one multiplexer installed, channel 01 on the module in the lowest slot is used as the reference for the entire instrument.

• Before configuring a thermocouple channel with an external

reference, you must configure the reference channel (channel 01) for a thermistor or RTD measurement. An error is generated if you attempt to select the external reference source before configuring the reference channel. An error is also generated if you change the function on the reference channel after selecting the external reference for a thermocouple channel.

•If you select a fixed reference temperature, specify a value between -20 °C and +80 °C (always specify the temperature in °C regardless of the temperature units currently selected).

•The accuracy of the measurement is highly dependent upon the thermocouple connections and the type of reference junction used. Use a fixed temperature reference for the highest accuracy measurements. The internal isothermal block reference provides the lowest accuracy measurements. For more information on reference junction temperature measurements and associated errors, see the sections on pages 345 and 352.

•The thermocouple check feature allows you to verify that your thermocouples are properly connected to the screw terminals for measurements. If you enable this feature, the instrument measures the channel resistance after each thermocouple measurement to

ensure a proper connection. If an open connection is detected (greater than 5 kΩ on the 10 kΩ range), the instrument reports an overload condition for that channel (or displays “OPEN T/C” on the front panel).

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34970A specifications

Agilent Technologies 34970A is a versatile data acquisition and measurement system that has gained popularity in various industries, including research and development, manufacturing, and education. The primary purpose of the 34970A is to offer an efficient solution for data collection, monitoring, and analysis, which can significantly enhance productivity and accuracy in testing applications.

One of the main features of the 34970A is its modular design, allowing users to customize the system according to their specific measurement needs. The mainframe can accommodate up to three plug-in measurement modules, which can include various types of measurements such as analog, digital, temperature, and frequency. This modularity provides flexibility for users to tailor the system to their requirements, making it highly adaptable to different applications.

Another notable characteristic of the Agilent 34970A is its impressive channel configuration. The system can support up to 120 measurement channels when fully configured, enabling extensive data acquisition without the need for multiple devices. This capability is essential for applications requiring simultaneous monitoring of multiple parameters or locations.

The 34970A utilizes advanced signal processing technologies to ensure high-accuracy measurements. The internal 6.5-digit resolution multimeter provides precise readings, while the device also supports various input types, such as thermocouples and RTDs for temperature measurements. The ability to perform mathematical functions, such as summation and averaging, on the acquired data further enhances its usability.

For data storage and management, the Agilent 34970A features built-in memory for storing up to 20,000 readings. Users can also easily transfer data to a PC through the RS-232 interface or GPIB (IEEE 488) for further analysis and reporting. Additionally, it offers the capability to program automatic data logging and scheduling of measurements, which streamlines the testing process and reduces manual intervention.

In terms of user interface, the 34970A is equipped with a large graphical display that provides clear visualization of measurement data and easy navigation through settings and options. The menu-driven interface makes it accessible for users of all skill levels, simplifying the setup and operation of the device.

Overall, the Agilent Technologies 34970A stands out for its modularity, high channel capacity, advanced measurement technologies, and user-friendly interface. As a reliable and efficient data acquisition system, it is well-suited for a wide range of applications, making it an essential tool for engineers and technicians looking to enhance measurement precision and efficiency.