Shunting
The act of connecting an electrical element in parallel with (across) another element. The shunting connection is shown in illus. a.
An example of shunting involves a measuring instrument whose movement coil is designed to carry only a small current for a full-scale deflection of the meter. To protect this coil from an excessive current that would destroy it when measuring currents that exceed its rating, a shunt resistor carries the excess current.
Illustration b shows an ammeter (a current-measuring instrument) with internal resistance RA. It is shunted by a resistor RS. The current through the movement coil is a fraction of the measured current, and is given by the equation below.
Similar connections and calculations are used in a shunt ohmmeter to measure electrical resistance. Shunt capacitors are often used for voltage correction in power transmission lines. A shunt capacitor may be used for the correction of the power factor of a load. In direct current shunt motors, the excitation (field) winding is connected in parallel with the armature. See Direct-current motor, Ohmmeter, Resistance measurement
In electronic applications, a shunt regulator is used to divert an excessive current around a particular circuit. In broadband electronic amplifiers, several techniques may be used to extend the bandwidth. For high-frequency extension, a shunt compensation is used where, typically, a capacitor is shunted across an appropriate part of the circuit. Shunt capacitors (or more complicated circuits) are often used to stabilize and prevent undesired oscillations in amplifier and feedback circuits. See Amplifier, Feedback circuit
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