Multimeter INEL 15050

Analog Meters

These meters operate through mechanical movements to indicate values on a dial. They are often used for measuring voltage, current, and resistance. Unlike digital meters, they provide a continuous display and can be affected by factors like parallax error. Common examples include voltmeters and ammeters.

d’arsonal movement

a DC moving coil-type movement in which an electromagnetic core is suspended between the poles of a permanent magnet.

Moving-Coil Meter

relies on current passing through a coil to move the coil in a magnetic field. When current flows, the field of the magnet acts on the coil so as to turn it against the restoring torque (twisting effort) of the springs or threads.

Galvanometers

This device is used on electrical circuits to know and measure the intensity and direction of electrical current.

Voltmeter

to measure voltage

Industrial standard resistance for a volt meter

20k ohms per volt DC, 5000 ohms per volt AC

Multirange Volmeters

Voltmeters designed to use one meter movement to measure several ranges of voltage

Multi range ammeters

Designed to operate on more than one range. This is done by connected the meter movement to different shunts

Clamp-On Ammeter

The jaw of this type of meter is clamped around one of the conductors supplying power to the load. The meter is clamped around only one of the lines.

Ohmmeter

Used to indicate resistance. The common volt-ohmmilliammeter (VOM) contains an ohmmeter.

An ohmmeter should always be readjusted to ___ when the scale is adjusted

Zero

Must never be connected to a live circuit

The ohmmeter uses its own internal power supply

Difference between digital meters and analog:

Digital meters display their readings in digits instead of a pointer and scale.

The low-impedance voltage tester

has a very large current draw compared with other types of voltmeters and should never be used to test low-power circuits.

The relatively high current draw of the voltage tester can be an advantage when testing certain types of circuits, however, because it is not susceptible to giving the misleading voltage readings caused by high-impedance ground paths or feedback voltages that affect other types of voltmeters.

Oscilloscope

is a type of electronic test instrument that graphically displays varying voltages of one or more signals as a function of time. Their main purpose is capturing information on electrical signals for debugging, analysis

Bridge Circuit

Used to measure values of resistance, inductance, and capacitance

Steps to reading a meter:

Determine the quantity the meter is set to measure

Determine the full range value of the meter

Read the meter

____ have a low resistance and must be connected in series with a load to limit the flow of current

Ammeters

Digital multimeters generally have an input impedance of 10 ____ on all ranges

Megaohms

The ____ measures the amplitude of voltage with respect to time

Oscilloscope

_____ contain a stationary coil and moveable coil

Wattmeters