Front Panel Operations 2

Configuring a Measurement Channel

Configuring a Channel to Measure Temperature

Perform the procedure in Figure 2-8 to configure a channel for measuring temperature with thermocouples, or Figure 2-9 to measure temperature with resistance-temperature detectors (RTDs). In preparation, the instrument must be in the inactive mode (not scanning or monitoring) and the desired channel must be selected (see Figure 2-3). To exit at any time (changes not saved), press the Ckey. The temperature scale, ºC or ºF, is set by the Temperature-Toggle Power-On procedure (see Figure 2-2). When under computer control, an open thermocouple default can be set by the TEMP_CONFIG command.

Thermocouples

Thermocouples are formed by joining two wires of dissimilar metals, which produce a voltage proportional to the temperature of the wire junction. The instrument conditions this voltage into temperature measurements. Voltage conditioning includes compensation for the type of thermocouple used and measurement-process compensation that uses a reference temperature sensor built into the Input Module (channels 1 to 20). The front panel terminals (channel 0) cannot be used for thermocouples. The instrument supports nine standard thermocouples, each identified with an American National Standards Institute (ANSI) alpha character (except [ ]): J, [C], B, S, R, N, T, E, or K. A thermocouple type is selected as part of the channel configuration. Table 2-3 summarizes the ranges and characteristics of the supported thermocouples. The instrument displays "otc" when an open thermocouple is detected (as selected with the TEMP_CONFIG command - see Chapter 4). A type "T" thermocouple is supplied with the instrument.

Resistance-Temperature Detectors

Resistance-Temperature Detectors (RTDs) are formed from coils or strips of metal, usually platinum, the resistance of which varies with temperature. The instrument conditions this resistance into temperature measurements. The instrument supports any platinum RTD that is calibrated to the IEC 751 Standard (a=0.00385 ohms/ohm/ºC). RTDs are characterized by their resistance at 0 ºC, which is called the "ice point" or R0. The most common R0 is 100 ohms. The instrument supports any IEC 751 Platinum RTD with an R0 from 000.00 to 999.99, with a default of R0=100.00. Since RTDs are resistance devices, they can be connected to the instrument using one channel (two- terminal connection) or two channels (four-terminal connection). A four-channel configuration provides increased measurement precision. Some RTDs can be purchased in a four-terminal configuration, facilitating a four-terminal connection. The two channels used in a four-terminal connection are a decade apart (n and n+10), for example, channel 3 (n) and 13 (n+10). Only the lower channel is configured.

Thermocouple Restrictions:

Channel 0. Thermocouple measurements cannot use channel 0.

Open Thermocouple. The instrument displays OTC when an open thermocouple is detected and ignores the channel while scanning.

Resistance Temperature Detectors Restrictions:

Four-Terminal Channels. Four-Terminal configurations are limited to channels 1 to 10

(n). The channel a decade higher (n + 10) is automatically reserved for use.

2-13

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Fluke 2635A user manual Configuring a Channel to Measure Temperature, Thermocouples, Resistance-Temperature Detectors
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2635A specifications

The Fluke 2635A is a highly advanced multichannel data acquisition system designed for engineers and technicians requiring precision and versatility in their measurement tasks. This instrument excels in monitoring and capturing data from various sources, making it a valuable tool in laboratories, production environments, and field applications.

One of the standout features of the Fluke 2635A is its ability to support up to 20 measurement channels. Users can simultaneously monitor multiple signals, which is crucial for complex testing scenarios where numerous variables need to be tracked. The device is equipped with a 6.5-digit precision measurement capability that ensures high accuracy and resolution in readings. This level of precision is particularly beneficial in applications such as environmental monitoring, research and development, and industrial process control.

The unit incorporates a variety of measurement modes, including voltage, current, temperature, and resistance, making it exceptionally versatile. The Fluke 2635A not only handles standard signals but also integrates with various transducers, providing extensive compatibility for users engaged in diverse testing applications.

To enhance data management, the Fluke 2635A offers advanced data logging capabilities. Data can be stored internally or transferred to external devices for further analysis. The internal memory can accommodate extensive datasets, which can be crucial in long-term monitoring tasks. Integration with external software enables users to analyze and visualize data effectively, allowing for informed decision-making based on comprehensive results.

The user interface is designed for ease of use, featuring a large, bright LCD display that clearly presents measurements and status information. The device is also equipped with a simple navigation system, allowing users to switch between channels and measurement types without hassle.

In terms of construction, the Fluke 2635A is built to withstand rigorous environments. It features a robust design that ensures reliability and durability, making it suitable for both laboratory settings and field operations. Furthermore, the device supports a wide temperature range, thus enabling usage in diverse conditions.

Overall, the Fluke 2635A is a powerful and flexible instrument that provides precise measurements across multiple channels, supporting a wide range of applications. Its advanced technology, combined with user-friendly features, makes it an essential tool for professionals in various fields. The combination of accuracy, flexibility, and durability solidifies its standing as a trusted choice for data acquisition and monitoring tasks.
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