shunting


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shunting

[′shənt·iŋ]
(electricity)
The act of connecting one device to the terminals of another so that the current is divided between the two devices in proportion to their respective admittances.

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.

With different choices of RS, the measuring range for the current I can be changed. See Ammeter, Current measurement

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

References in periodicals archive ?
Devinsky, "Delayed intracerebral hemorrhage after ventriculoperitoneal shunting," Neurosurgery, vol.
A PFO as the main cause of acute hypoxic respiratory failure is rare and usually it is not sufficient to cause right-to-left shunting to elicit desaturation.
It is critical to identify the state of a patient's priapism throughout the treatment process to distinguish between low-flow states, where shunting is indicated, and high-flow states, where shunting is not indicated.
DISCUSSION: Ventriculo-peritoneal shunting is the most frequent method used for CSF diversion.
[sup][5] Its effectiveness beyond surgical shunting in bridging to hepatic transplantation, to some extent, was arguable.
Management of hydrocephalus in children with medulloblastomas: prognostic factors for shunting. Pediatr Neurosurg 1994;20: 240-7.
Our experience is the first description of shunting in the civilian setting before hospital transfer.
Routine or selective carotid artery shunting for carotid endarterectomy (and different methods of monitoring in selective shunting).
On confirmation of raised intra cranial pressure, they were subjected to ventriculoperitoneal shunting to relieve hydrocephalus.
Shunting House and Shunting Cottage, Acklington, are for sale through Smiths Gore at pounds 425,000, tel: 01434 632001.
She speculated that circulatory shunting of unfiltered microaggregates and vasoactive chemicals to the cerebral vasculature may occur with right-to-left shunting and produce recurrent transient ischemia, theoretically increasing the risk of cognitive dysfunction.
The O2 score is the simplest and most expedient measure of intrapulmonary shunting. The O2 score is inversely related to pulmonary shunting.