Definition of shunt

The word "shunt" originates from the 18th-century English railway terminology. It originally described a diverging route or switch used to divert trains from their regular path. The use of the term spread to electrical engineering in the 1800s, where it was applied to a type of circuit that diverts current from its intended path. In electrical engineering, a shunt is a low-ohm (resistive) component which, when used in parallel alongside other electrical components, reduces the overall resistance or impedance of the circuit. This is known as parallel shunting or parallel stealing of power, and is used to improve the efficiency of power transmission systems or to protect equipment from excessive voltage during testing or operation. The use of shunts in underwater electrical cable systems, particularly for long-distance submarine power cables, helps to reduce power losses due to resistance, known as Ir(IRE) = R(Ω) * I(A)² losses, by reducing the total impedance of the system overall. It also improves the reliability of these systems by enabling quick and convenient testing of individual cable sections during manufacture and installation, as any faulty cable line or component can be isolated and steered away from the main electrical path using a shunt. In medical engineering and physics, shunts are also used to redirect fluids, such as blood or pressurized gases, from one point to another, like a valve. The use of blood shunts in medical conditions like congestive heart failure allows for a portion of blood to be rerouted from the venous system to the arterial system, reducing the overall vascular resistance of the body, and thereby easing cardiovascular symptoms. In summary, the word "shunt" has evolved from its railway roots to describe a variety of circuit and fluid components that divert or redirect something from its intended path, with a diverse range of practical applications in electrical, medical and other fields where efficient power, fluid, or electrical management is necessary.