# PesWiki.com

## PowerPedia:Ammeter

Lasted edited by Andrew Munsey, updated on June 14, 2016 at 9:23 pm.

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An ammeter is a `There was an error working with the wiki: Code[2]`. Electric currents are measured in Amperes, hence the name. The word "ammeter" is commonly misspelled or mispronounced as "ampmeter" by some.

#### Description

The earliest design is the D'Arsonval `There was an error working with the wiki: Code[3]` deflection, where current passing through a coil causes the coil to move in a Magnetic field. The Voltage drop across the coil is kept to a minimum to minimize resistance in any circuit into which the meter is inserted.

Moving iron ammeters use a piece or pieces of `There was an error working with the wiki: Code[4]`) wire. This type of meter responds to both Direct current and Alternating current currents (as opposed to the moving coil ammeter, which works on Direct current only).

To measure larger currents, a `There was an error working with the wiki: Code[5]` is placed in `There was an error working with the wiki: Code[6]` with the meter. Most of the current flows through the shunt, and only a small fraction flows through the meter. With this solution, arbitrarily large currents can be measured with a single meter. Traditionally, the meter used with a shunt reaches full-scale deflection when a voltage of 50mV is placed across its coil, so shunts are typically designed to produce a voltage drop of 50mV when carrying their full rated current.

More modern ammeter designs are non-mechanical, or digital, and use an `There was an error working with the wiki: Code[8]` to measure the voltage across the shunt resistor. The ADC is read by a microcomputer that performs the calculations to display the current through the resistor.

One problem with the use of an ammeter is the need for the meter to be inserted into the circuit and become part of it. Mistakenly placing the ammeter in parallel with a circuit will blow the fuse, possibly damaging the meter and causing injury. In AC circuits, an inductive coupling adapter converts the magnetic field around a `There was an error working with the wiki: Code[7]` into a small AC current that can be easily read by a meter. See `There was an error working with the wiki: Code[9]`. In a similar way, accurate DC non-contact ammeters have been constructed using `There was an error working with the wiki: Code[10]` magnetic field sensors.

#### Related

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List of electronics topics

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#### References

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`There was an error working with the wiki: Code[1]`, Wikipedia: The Free Encyclopedia. Wikimedia Foundation.

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