ILM-030104a Measurement Equipment

The common types of meters are

Voltmeters, Ammeters, Ohmmeters, Megohmmeters, and Wattmeters

Digital Meters

Fast-acting and easy to read. They display numerical values, which eliminates estimating and reading errors. They are typically battery-powered or cord-connected.

Analog Meters

Uses a needle or pointer and a calibrated scale to indicate electrical values. They typically do not require a bettery.

What scales are on a Analog display

Linear or Non-Linear

A scale that has equally spaed divisions

Linear scale

A scale where the divisions are not equally spaced

Non-linear scale

A display that sometimes provide better information than numbers on a digital display. They are also informative for determining when values are increasing, decreasing, or approaching critical values.

Analog displays

Multimeter

The most common type of electrical meter that combines more than one function into a single meter for economy and versatility, such as a voltmeter, ohmmeter, or an ammeter.

Voltmeter

Measures the voltage between two points on an electrical circuit.

Voltage Tester

A type of single-purpose voltmeter. There are three types: One-lead testers, Two-lead testers, and Non-contact voltage testers (NCVT’s).

Ammeter

Measures the amount of electrical current flowing through a circuit. These measurement devices could be either: Dedicated ammeters or A selected function of a multimeter.

Ohmmeter

Measures the resistance of a device or circuit.

Megohmmeter

Specially designed ohmmeters that measures very high resistances, typically used to test conductor insulation.

Wattmeter

Measures the electrical power in a circuit. It may be stand-alone, single-purpose meter, or a selected function of a multimeter.

The four important factors when selecting an electrical meter

1) The electrical measurement required

2) Whether the electrical circuit is energized or de-energized

3) The value you expect to obtain from the meter

4) Whether polarity is important in the electrical measurement

What would happen if DC volts are selected instead of AC volts?

The meter will say the circuit is de-energized when it actually is energized. This can lead to injury and/or equipment damage.