Ayrton shunt

Ayrton shunt switching principle

Ayrton shunt or universal shunt is a high-resistance shunt used in galvanometers to increase their range^[1] without changing the damping.^[2] The circuit is named after its inventor William E. Ayrton.^[3] Multirange ammeters that use this technique are more accurate than those using a make-before-break switch.^[4] Also it will eliminate the possibility of having a meter without a shunt which is a serious concern in make-before-break switches.^[5]

The selector switch changes the amount of resistance in parallel with R_m (meter resistance). The voltage drop across parallel branches is always equal. When all resistances are placed in parallel with R_m maximum sensitivity of ammeter is reached.^[5]

Ayrton shunt is rarely used for currents above 10 amperes.^[6]

References

1. Basic Electrical Engg: Prin & Appl 2009, p. 826.
2. Graf 1999, p. 50.
3. "Ayrton shunt". Merriam-Webster, Incorporated. Retrieved 11 January 2014.
4. Herman 2013, p. 201.
5. Bakshi & Bakshi 2009, p. 3-41.
6. Herman 2010, p. 276.

• Graf, R.F. (1999). Modern Dictionary of Electronics. Electronics & Electrical. Newnes. ISBN 9780750698665. Retrieved 2014-01-11.
• Basic Electrical Engg: Prin & Appl. McGraw-Hill Education (India) Pvt Limited. 2009. ISBN 9781259081330. Retrieved 2014-01-11.
• Herman, S. (2013). Electrical Studies for Trades. Cengage Learning. ISBN 9781133278238. Retrieved 2014-01-11.
• Bakshi, U.A.; Bakshi, A.V. (2009). Electrical Instrumentation. Technical Publications. ISBN 9788184317336. Retrieved 2014-01-11.
• Herman, S. (2010). Delmar's Standard Textbook of Electricity. Cengage Learning. ISBN 9781111539153. Retrieved 2014-01-11.