SmartResistor an Automated Resistance Standard
US Pat. No. 6,798,214
Description
Resistance lab in a box
The SmartResistor combines, into one transportable device, the three items needed to maintain resistance: a set of standard resistors, a controlled temperature bath and the measurement data defining those resistors.
Advantages of the SmartResistor
Eight resistance Standards
To maintain and disseminate the ohm, a laboratory must have a set of resistance standards, usually at decade values (1 W, 10 W, 100 W, etc.). The standard SmartResistor contains eight resistors. A typical model contains eight decade values covering the range from 1 W to 10 MW. However, any eight resistance values may be specified at the time of order. Due to power and leakage limitations, the standards should be between 0.1 W and 10 MW.
Constant temperature bath
Traditional resistance standards are usually held in a constant temperature oil bath; these baths are bulky, noisy, and can not be transported. The SmartResistor contains a constant temperature enclosure, allowing portability. The control circuitry has sufficient power to overcome wide changes in ambient temperature. The nominal setting is 25.00 °C. Initial tests on this enclosure indicate a stability better than 10 mK.
Environmental immunity
The standards are hermetically sealed, for immunity from changes in barometric pressure and relative humidity.
Characterization of standards
A resistance standard has no value without its characterization. This critical data includes a reference value in ohms, coefficients of temperature, power coefficient, frequency response and its drift over time. The SmartResistor's internal computer maintains all this data and displays it to the user. The data is available for integration into automated systems.
Corrected for drift
As time passes, the SmartResistor's calendar will apply drift corrections to the displayed value. The SmartResistor's software generates and maintains control charts for each of its eight standards.
Low thermal emf scanner
The SmartResistor's low-thermal eight channel scanner is by Data Proof. The scanner allows automated ratio buildups. Any of the eight resistance standards may be selected as R1 or R2 on the front panel.
Internal datalogger
The SmartResistor contains a battery powered temperature logger, to monitor and warn of exposure to potentially damaging temperature extremes during storage or transit.
Cost Savings of the SmartResistor
A single SmartResistor is designed to replace eight resistance standards, a constant temperature bath, a low thermal emf scanner, a precision thermometer, a temperature datalogger and resistance maintenance software, at a significantly lower cost than these components.
Automating the Resistance Lab
The SmartResistor is designed with simple, intuitive operator controls. All functions and controls can be integrated into an automated system via the SmartResistor's interfaces. The standard interfaces supplied include ethernet and IEEE ports.
Protecting Resistance Standards
Traditional resistance standards can be permanently damaged by exposure to temperature extremes. The SmartResistor contains a battery-powered temperature datalogger, constantly monitoring its internal temperature. Even in storage, the logger will sample and store temperatures hourly for a period of approximately two years.
A rugged transit container is available for the SmartResistor.
Future Developments
The SmartResistor Model SR covers the range from 0.1 W to 10 MW. A SmartShunt, Model SS, is planned for use as a low resistance standard, containing five decade values from from 1 W to 0.000 01 W. It may be used for high accuracy current measurement, up to 300 amps. A high resistance standard, Model SH, is planned for resistance between 1 MW to 1 TW. Extended models are planned, including a high current shunt.
Longevity
The SmartResistor is designed for extended use. Care has been exercised to select the most reliable and rugged components. The software runs on Microsoft Windows XP. Software upgrades will be provided at no cost to customers as they become available. The SmartResistor is internet compatible, so that evaluation, uploads and diagnostics can be performed anywhere in the world.
The SmartResistor carries a two year parts and labor warrantee.
Technical Support
Ohm-Labs provides lifetime technical support for all products - upgrades are generally available at no cost.
Related Information
Thank you for your interest in the SmartResistor. We welcome any comments or suggestions you may have. Please contact us with any questions you may have concerning resistance standards.
