shunt(redirected from postcaval shunt)
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an electrical or magnetic conductor connected in parallel with an electric or magnetic circuit to divert part of the electric current or magnetic flux when it is undesirable or impossible to pass all the current or flux through the circuit. For example, when a shunt is used to extend the measuring range of an ammeter, the current Ix being measured is divided between the shunt and the ammeter in inverse proportion to their respective resistances, Rs and RA; in this case Ix = IA (1 + RA/RS) = IAks, where IA is the value of the current as determined from the ammeter readings and ks is the shunting factor. For convenience in making current measurements, the resistance of the shunt is chosen so that ks is equal to 10,100, or 1000.
Shunts are manufactured in the form of plates, bands, and wires, primarily of manganin or constantan (for electrical shunts) or of a soft magnetic material (for magnetic shunts).