Learn key terms related to digital multimeters. This glossary will help you understand the technical specifications, safety features, and functions to choose the perfect tool for your electrical projects. For detailed information about a specific model, always refer to the official user manual provided by the manufacturer, such as the commercial electric dmm-8132 manual.
A multimeter is a handheld instrument used to diagnose electrical circuits, ranging from household wiring to complex electronic devices. Understanding the differences between measurement modes, safety standards, and display features is key to making an informed decision and ensuring personal safety while working with electricity.
Glossary of Terms for “Multimeters”
Multimeter — an electronic measuring instrument that combines several measurement functions in one unit. Typical features include the ability to measure voltage (volts), current (amps), and resistance (ohms).
Digital Multimeter (DMM) — the most common type of multimeter that displays measurements as a numerical value on a digital LCD screen. It offers higher accuracy and reading precision compared to analog meters.
Analog Multimeter — a traditional type of multimeter that uses a moving needle to indicate values on a printed scale. It is useful for observing fluctuations in readings but is generally less precise than a digital multimeter.
Voltage (Volts) — the electric potential difference between two points in a circuit. Multimeters can measure both DC Voltage (Direct Current, from batteries) and AC Voltage (Alternating Current, from wall outlets).
Current (Amperage) — the flow of electric charge through a conductor, measured in Amperes (A). Measuring current often requires the user to connect the probes in series with the circuit.
Resistance (Ohms) — a measure of how much a component or wire resists the flow of electric current. It is used to check if a circuit is open (broken) or closed (continuous).
Continuity — a specific test mode that determines if an unbroken electrical path exists between two points. Most multimeters emit a beep sound when continuity is detected, allowing for quick troubleshooting of wires and fuses.
True RMS — stands for “Root Mean Square,” a feature found in advanced multimeters. It allows the device to accurately measure AC voltage in non-linear circuits (like those with variable speed motors or computers), providing a “true” reading of the effective voltage.
Auto-Ranging — a convenient feature where the multimeter automatically selects the correct measurement range (e.g., millivolts vs. volts) based on the input signal. This eliminates the need for the user to manually dial in the correct scale.
Manual-Ranging — a setting where the user must manually select the appropriate range on the dial. This offers more control but requires the user to have a better understanding of the expected electrical values.
Input Jacks (Ports) — the sockets on the front of the multimeter where the test leads are plugged in. Common jacks include “COM” (Common/Ground), “VΩ” (Voltage and Resistance), and “A” or “mA” (Current).
Test Leads (Probes) — the insulated wires with metal tips used to connect the multimeter to the circuit being tested. Quality leads are essential for safety and accurate readings.
Resolution — the smallest increment of change that the multimeter can display. For example, a resolution of 0.1V means the display can show voltage changes down to one-tenth of a volt.
Accuracy — a specification that indicates how close the multimeter’s reading is to the actual true value of the signal being measured. It is usually expressed as a percentage of the reading.
Safety Category (CAT Rating) — a safety rating system (CAT I, II, III, IV) that defines the environment in which the multimeter can be safely used without risking injury from transient voltage spikes, such as lightning or power surges.
Data Hold — a function that freezes the current reading on the display, allowing the user to record a measurement even after removing the probes from a hard-to-reach location.
Diode Test — a mode used to check the operation of diodes and ensure they allow current to flow in only one direction. It also often helps to check the functionality of LEDs.
Capacitance — the ability of a component (like a capacitor) to store an electrical charge. Many modern multimeters can measure capacitance in microfarads (µF) to verify if a capacitor is faulty.
Frequency (Hz) — a measurement function that determines the number of cycles per second in an AC signal. This is useful for testing frequency-dependent equipment and motors.
Duty Cycle — the percentage of time that a digital signal is “on” versus “off” during a cycle. This is often used by automotive technicians to test fuel injectors and sensors.
Non-Contact Voltage (NCV) — a safety feature found in some multimeters that allows the user to detect the presence of AC voltage in a wire without physically touching the conductor with the metal probes.
Relative Mode (REL) — a feature that subtracts the lead resistance or interference from the current reading, allowing for more precise measurements of low resistance values.
Backlight — a built-in light that illuminates the LCD screen, making the multimeter easy to read in dark or dimly lit environments.