Chapter 8 Tutorial

Measurement Fundamentals

Temperature Measurements

A temperature transducer measurement is typically either a resistance or voltage measurement converted to an equivalent temperature by software conversion routines inside the instrument. The mathematical conversion is based on specific properties of the various transducers. The mathematical conversion accuracy (not including the transducer accuracy) for each transducer type is shown below.

Transducer

Conversion Accuracy

 

 

Thermocouple

0.05 °C

RTD

0.02 °C

Thermistor

0.05 °C

 

 

Errors associated with temperature measurements include all of those listed for dc voltage and resistance measurements elsewhere in this chapter. The largest source of error in temperature measurements is generally the transducer itself.

Your measurement requirements will help you to determine which temperature transducer type to use. Each transducer type has a particular temperature range, accuracy, and cost. The table below summarizes some typical specifications for each transducer type.

Use this information to help select the transducer for your application. The transducer manufacturers can provide you with exact specifications for a particular transducer.

Parameter

Thermocouple

RTD

Thermistor

Temperature Range

-210°C to 1820°C

-200°C to 850°C

-80°C to 150°C

Measurement Type

Voltage

2- or 4-Wire Ohms

2- or 4-Wire Ohms

Transducer Sensitivity

6 ∝V/°C to 60 ∝V/°C

≈ R0 x 0.004 °C

≈ 400 Ω /°C

Probe Accuracy

0.5 °C to 5 °C

0.01 °C to 0.1 °C

0.1 °C to 1 °C

Cost (U.S. Dollars)

$1 / foot

$20 to $100 each

$10 to $100 each

Durability

Rugged

Fragile

Fragile

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Agilent Technologies 34970A manual Temperature Measurements, Rtd
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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.
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