Theory of Operation

4

 

Overall Functional Description

Operation in the 11A DC Range

4-5.

 

For the dc current function, the 5700A is configured for the dc 2.2V range. The 5700A 2V dc range drives an error amplifier with an input impedance of 40 kΩ. The gain of this amplifier is determined by this 40 kΩ resistor with a 4 kΩ feedback resistor, and the value of the precision shunt. The 5725A uses a 0.02Ω shunt for the 11A function. There is no feedback to the 5700A.

The 5725A monitors the error amplifier output voltage using the 16-channel multiplexer. One channel of the multiplexer, ICOMPL M, is scanned every 30 milliseconds or faster, with its output compared to -2V from the DAC. If the peak error amplifier output is more negative than the dac voltage, MONCOMP goes LOW and is read by bit 6 of port 5 of U507, the CPU. This indicates an overload condition, and lights the OVERLOAD LED. If a later scan shows the same result, the CPU trips the Current Amplifier into standby and reports this condition to the 5700A.

A soft-start from standby to operate transitions reduces sudden current changes. This allows the 5725A to drive inductive loads such as power meters and clamp-on type current probes.

Operation in the 11A AC Range

4-6.

For ac current operation, input to the 5725A comes from the 5700A Oscillator. The 5700A Oscillator is configured for the 2.2V ac range, with sensing back to the 5700A Oscillator coming from the current shunt through the calibration amplifier circuit (on the Current Assembly).

Voltage and Current Standby Modes

4-7.

When a change in output function is selected, the 5725A goes through voltage or current standby mode before connecting the output to the 5725A binding posts, or to the 5700A. Voltage or current standby allows for local sensing within the 5725A, and for establishment of a known input condition in current and ac voltage.

Voltage Standby

4-8.

In voltage standby, the 5700A binding posts are completely disconnected from the rest of the instrument circuitry, and the 5725A high voltage output and sense lines (B-OUT HI and B-SENSE HI) are disconnected from the 5725A/5700A connector. The High Voltage Amplifier remains powered from the high voltage supply, but its input is grounded by pulling CLAMPD, and its output (MV OUT) is disconnected from the output transformers. Analog monitor circuitry continues to check the voltage and current on the high voltage supplies as well as the heat sink temperatures and cable integrity. It prevents the 5725A from switching to operate if a fault is present.

Current Standby

4-9.

In current standby, the binding posts are disconnected from the instrument circuitry, but all 5725A/5700A connections are made as in the operate mode. In dc current standby, the 5700A DAC supplies a voltage that corresponds to the dc current selected. In ac current standby, 5725A relay settings are identical to those for dc current standby. The 5700A Oscillator supplies an ac voltage level that corresponds to the selected output current and frequency.

4-7

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Fluke 5725A Operation in the 11A DC Range, Operation in the 11A AC Range, Voltage and Current Standby Modes

5725A specifications

The Fluke 5725A is a high-performance, multifunctional temperature calibration source designed to meet the demanding requirements of laboratory and industrial environments. Renowned for its accuracy, reliability, and versatility, the 5725A serves as a powerful tool for engineers and technicians engaged in temperature calibration processes.

At the core of the 5725A is its advanced measurement technology, which allows for precision temperature calibrations across a wide range. With an operating temperature range from -200°C to 660°C, it caters to various applications, making it suitable for calibrating thermocouples, resistance temperature detectors (RTDs), and other temperature measurement devices.

One of the standout features of the Fluke 5725A is its outstanding accuracy, boasting a specified uncertainty of just ±0.15°C. This level of precision ensures that users can maintain compliance with regulatory standards and regulatory requirements in fields such as aerospace, pharmaceuticals, and manufacturing.

The Fluke 5725A is equipped with dual-channel capabilities, allowing users to calibrate two devices simultaneously. This enhances productivity by minimizing downtime and optimizing workflow efficiency. The intuitive touchscreen interface simplifies operations, enabling users to view measurements, set up test parameters, and access historical data with ease.

Versatile connectivity options such as USB and Ethernet enable seamless integration into existing systems and allow for data transfer, remote control, and configuration. This feature empowers technicians to conduct calibrations efficiently, whether on-site or remotely.

The robust design of the Fluke 5725A ensures its durability in demanding environments. Built with high-quality materials, it is resistant to shocks and vibrations, making it suitable for use in manufacturing plants and laboratories where equipment may be subjected to harsh conditions.

Another notable characteristic of the 5725A is its ability to generate stable temperature outputs with minimal drift, contributing to consistency in calibration results. Its built-in self-test functionality helps ensure that the unit remains in peak operating condition, giving users confidence in their calibration processes.

In summary, the Fluke 5725A is a top-tier temperature calibration source that excels in accuracy, reliability, and user-friendliness. Whether in laboratory settings or industrial applications, its advanced technologies and features make it an essential tool for professionals tasked with maintaining precision in temperature measurements.