Kelvin bridge


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Kelvin bridge

A specialized version of the Wheatstone bridge network designed to eliminate, or greatly reduce, the effect of lead and contact resistance and thus permit accurate measurement of low resistance. The circuit shown in the illustration accomplishes this by effectively placing relatively high-resistance-ratio arms in series with the potential leads and contacts of the low-resistance standards and the unknown resistance. In this circuit RA and RB are the main ratio resistors, Ra and Rb the auxiliary ratio, Rx the unknown, Rs the standard, and Ry a heavy copper yoke of low resistance connected between the unknown and standard resistors.

A Kelvin bridge used to measure an unknown low resistanceenlarge picture
A Kelvin bridge used to measure an unknown low resistance

As with the Wheatstone bridge, the Kelvin bridge for routine engineering measurements is constructed using both adjustable-ratio arms and adjustable standards. However, the ratio is usually continuously adjustable, over a short span, and the standard is adjustable in appropriate steps to cover the required range. See Bridge circuit, Resistance measurement, Wheatstone bridge

Kelvin bridge

[′kel·vən ‚brij]
(electricity)
A specialized version of the Wheatstone bridge network designed to eliminate, or greatly reduce, the effect of lead and contact resistance, and thus permit accurate measurement of low resistance. Also known as double bridge; Kelvin network; Thomson bridge.
References in periodicals archive ?
It is named for William Thomson, Lord Kelvin, who invented the Kelvin bridge in 1861 to measure very low resistances.
Hosted by DJ Mary Hill (Jonnie Wilkes) and DJ Kelvin Bridge (Keith Mclvor, aka Mount Florida), this regular Sunday-night party in Glasgow is a cross between buccaneer de Stijl (you'll just have to take my word for it) and a knees-up with your family.
But at least 28-year-old Oddbins assistant Martine Healy, above, from Kelvin Bridge showed enough bottle to get her hands on the brew in plenty of time.