How Do Amp Meters Work?

An amp meter measures the electric current in a circuit.

Introduction

Electric current is measured with the physical unit amperes and the amp meter gets its name from the amperes it measures. Amp meters can measure both alternating AC current and direct DC current. Amp meters are available both with analog and digital readings. Amp meters are used in equipment or modes of transport that use charged batteries. They help in determining what is going in the electrical system of a vehicle or equipment. They monitor batteries and determine the charge rate in batteries. Portable hand held ammeters are used for maintaining industrial and commercial electric equipment by temporarily clipping it on the equipment to measure the correctness of the current flowing through.

An amp meter measures the electric current in a circuit. Electric current is measured with the physical unit amperes and the amp meter gets its name from the amperes it measures. Amp meters can measure both alternating AC current and direct DC current. Amp meters are available both with analog and digital readings. Amp meters are used in equipment or modes of transport that use charged batteries. They help in determining what is going in the electrical system of a vehicle or equipment. They monitor batteries and determine the charge rate in batteries. Portable hand held ammeters are used for maintaining industrial and commercial electric equipment by temporarily clipping it on the equipment to measure the correctness of the current flowing through.

The Shunt

The shunt is the most important part of an amp meter. A resistor called a shunt is placed in an amp meter to measure large amounts of electric currents

DC Amp meter

A DC amp meter is a simple amp meter. Direct current is measured through a resistor or shunt placed in line with the circuit. The voltage is measured across the shunt.

AC Amp Meter

An AC amp meter is used in two ways. One AC amp meter uses a system similar to a DC amp meter. The only difference is that an AC amp meter uses a bridge diode instead of a regular shunt as a resistor to measure current. The bridge diode changes negative into positive current to facilitate calibration and measurement. This is called the direct AC amp meter. The other type of AC amp meter works by emitting an electromagnetic field. A coil around the wire will pick up the field and run it through a resistor or shunt and measure the voltage of the electric current. The voltage drives a needle to help read the measurements of the current. This is called an indirect amp meter. Some AC amp meters are moving iron type amp meters. The magnetic field is attracted by a piece of metal mounted at one end of a needle. This type of moving iron amp meter can work also with DC.

Zero Center Amp Meter

Scientific and industrial equipment need amp meters that measure current with both polarities. These amp meters are typically used to measure current within a battery. To effectively measure current within both polarities, zero center amp meters are placed in series with a battery. When the battery is charged, the needle moves in one direction usually to the right and when the battery is discharged, the needle moves the other direction. This type of amp meter is commonly used in batteries of automobiles and, boats. Zero Center Amp Meter

Scientific and industrial equipment need amp meters that measure current with both polarities. These amp meters are typically used to measure current within a battery. To effectively measure current within both polarities, zero center amp meters are placed in series with a battery. When the battery is charged, the needle moves in one direction usually to the right and when the battery is discharged, the needle moves the other direction. This type of amp meter is commonly used in batteries of automobiles and, boats.

Digital Amp Meters

Digital amp meters essentially give a digital reading of the charge of the current or battery. They are popular because they are easier to read and give accurate readings. These amp meters use an analog converter. This analog converter measures the voltage across the shunt and provides a reference voltage for electronic measurement. The digital display reads the amount of electric current or charge through the shunt.

About the Author

Giselle Diamond is a freelance writer and has been writing since 1999. Diamond is experienced in writing in all genres and subjects, with distinguished experience in home and garden, culture and society, literature and psychology. Diamond has a Master of Arts in English and psychology from New York University. Diamond has articles published on both eHow and LiveStrong.