A Kelvin bridge (also called a Kelvin double bridge) is a measuring instrument invented by William Thomson, 1st Baron Kelvin. It is used to measure an unknown electrical resistance below 1 Ω. Its operation is similar to the Wheatstone bridge except for the presence of additional resistors. These additional low value resistors and the internal configuration of the bridge are arranged to substantially reduce measurement errors introduced by voltage drops in the high current (low resistance) arm of the bridge [1].
There are some commercial devices reaching accuracies of 2% for resistance ranges from 0.001 to 25 ohms. Often, ohmmeters include Kelvin bridges, amongst other measuring instruments, in order to obtain large measure ranges, for example, the Valhalla 4100 ATC Low-Range Ohmmeter
See also
External links
- Kelvin Bridge
- Kelvin Bridge KB3 Data Sheet
- Valhalla 4100 ATC Low-Range Ohmmeter specifications
- Methods of Measuring Electrical Resistance - Edwin F. Northrup, 1912, full-text on Google Books - see chapter 6
References
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