Fluke Corporation

Richard W Walker

David W Farley

Allen Erik Sjogren

Michael W Hirst

Frank E Liebmann

Jeff M Elrod

Tian Xia

Eric Nerdrum

Jiajun Yan

Jia Jun Yan

A calibration device includes a tank, a propeller disposed within the tank, a motor coupled to the propeller, a processor coupled to the motor, and a memory. The memory stores instructions that, when executed by the processor, cause the motor to rotate at a specified speed based on input an indication of an actual speed of the motor. The memory may store instructions that cause the device to dynamically change the speed of the motor based on the viscosity of a fluid in the tank, which changes as the temperature of the fluid changes. In addition, the memory may store instructions that cause the device to determine whether the fluid in the tank is deteriorated, and to provide an operator alert in response to determining that the fluid is deteriorated.

Calibration bath with stir motor closed-loop control and stirring viscosity detection and adjustment

Systems and methods that provide measurement of liquid levels in a container, such as a calibration bath container, may utilize an acoustic transducer subsystem that includes one or more acoustic transducers that are controlled by a controller. The acoustic transducer subsystem emits acoustic signals toward a surface of a liquid in a container, and detects reflected acoustic signals that are reflected from the surface of the liquid. The liquid level sensor utilizes an acoustic waveguide subsystem to allow the acoustic transducer subsystem to be spaced apart from the liquid, which protects the acoustic transducer system another other components from damage due to heat, liquid, and vapor. The acoustic waveguide subsystem also channels the emitted and reflected acoustic signals to prevent substantial scattering of the signals within the container, which greatly improves the accuracy of the liquid level sensor.

Calibration bath with acoustic liquid level sensor

The core of a high temperature furnace has an elongated central test cavity for testing/calibration of a temperature-sensitive component, such as the probe of a thermocouple. At least three electrical heating elements as positioned adjacent to the test cavity, including two elements adjacent to the opposite end portions of the test cavity, respectively, and a center element between the end elements. A uniform temperature profile is maintained in the cavity by control circuitry that manages the supply of electrical power to the heating elements, by periodically configuring interconnections of the elements during multiple phases of a duty cycle. The duty cycle includes a first phase in which current is passed through the center element, a second phase in which current is passed through the end elements in series, and a third phase in which current is passed through one of the end elements and also through the center element without passing current through the other end element.

High temperature furnace having reconfigurable heater circuits

One or more embodiments are directed to a resistance bridge measurement circuit configured to perform an internal self-check. The resistance bridge measurement circuit may include two or more internal resistors. In one embodiment, the resistance bridge measurement circuit may be configured to measure a first voltage across one of the resistors and a second voltage across a combination of the two resistors. The measured voltages may be converted to a resistance ratio and compared to an expected value. In another embodiment, the resistance bridge measurement circuit may be configured to measure a third voltage across the other of the two resistors and a fourth voltage across a combination of the two resistors. The measured voltages may be converted to corresponding resistance ratios, summed and compared to an expected value.

Internal self-check resistance bridge and method

One or more embodiments are directed to a resistance bridge having two voltage measurements circuits that function in tandem. In one embodiment, a constant current source may be applied to two resistors coupled in series, in which the first resistor has a known resistance and the second resistor has a resistance to be determined or verified. A first measurement circuit may measure a first voltage across the first resistor and at substantially the same time a second measurement circuit measures a second voltage across the second resistor. The voltage of each resistor is converted to a ratio. Based on the ratio and the resistance of the first resistance, the resistance of the second resistor may be calculated.

Resistance bridge architecture and method

The present invention is a system and method for temporarily storing electrical energy to power sensitive measurement circuits. In one embodiment, a switch-mode power converter is operable to charge an energy storage device. After the energy storage device is sufficiently charged, the switch-mode power converter is powered off so that sensitive measurements may be made without being affected by noise or interference caused by the switch-mode power converter. Once the measurement has been made, the switch-mode power converter is powered on and provides power to the energy storage device to recharge the energy storage device so that a subsequent measurement may be made.

System and method for using stored electrical energy to quiet power sensitive measurement circuits

A temperature calibration device uses Peltier cells for heating and cooling. The Peltier cells are connected to a relay that connects the cells to each other in one configuration for heating and a different configuration for cooling. The Peltier cells also receive supply voltages having different magnitudes and polarities for heating and cooling. By changing the manner in which the Peltier cells are connected to each other and using different supply voltages for heating and cooling, the cells are able to operate closer to their specified maximum temperature differential without sacrificing the useful life of the cells.

Temperature calibration device having reconfigurable heating/cooling modules to provide wide temperature range

Instrument having oblique mounted terminal posts

The present invention is directed to an instrument having at least one terminal post having a longitudinal axis extending therefrom such that the longitudinal axis is at an oblique angle relative to a surface of the instrument. In one embodiment, each terminal post is mounted to a circuit board such that a first surface of each terminal post projects in a first direction. In this embodiment, a rear surface of each terminal post is beveled and coupled to a first surface of the circuit board. The beveled rear surface of the terminal posts defines the oblique angle at which the longitudinal axis of the each terminal post is relative to a surface of the instrument.

A temperature calibration device uses Peltier cells for heating and cooling. The Peltier cells are driven by a power controller that gradually changes the power applied to the Peltier cells from a starting power to a target power. However, during this transition, the power controller holds the power applied to the Peltier cells constant for a period to minimize the stress on the Peltier cells. This period of constant period may last until the temperature of an object reaches a predetermined temperature, or it may have a fixed or variable duration, which may be based on the difference between the starting power and the target power. By changing the power applied to the Peltier cells in this manner, the useful life of the Peltier cells is preserved.

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Alpine, UT, United States of America

Richard W Walker