Overview: This article covers multimeters, highlighting their functions, types, and key components. It also features the Fluke 87V MAX, a durable, high-precision tool designed for demanding industrial environments.

If an electrical or electronic appliance is malfunctioning and the cause of the issue is uncertain, a multimeter is an excellent method for identifying the defect.

What Is a Multimeter?

A multimeter is an advanced electronic measuring instrument that integrates multiple functions, serving as a voltmeter, ammeter, and ohmmeter in one device. It is essential for testing and diagnosing electrical circuits. It provides precise measurement values that can help determine which component has failed.

Multimeters are lightweight, portable, handheld devices for basic testing and are highly accurate. They are widely used for troubleshooting electrical problems in electronic equipment, motor controls, household appliances, power supplies, and wiring systems.

Function

As a voltmeter, it measures the electrical potential difference between two points in a circuit. It can measure direct current (DC) and alternating current (AC) voltages.

As an ammeter, a multimeter measures the electric current flowing through a circuit or component. Like voltage, most multimeters can measure both DC and AC currents.

As an ohmmeter, multimeter, measures electrical resistance within a component or circuit, helpful in testing resistors, checking continuity, and identifying open or short circuits.

Additionally, modern multimeters can also be used in the measurement of capacitance, frequency, diode, and transistor testing, and temperature measurement.

Types

There are two primary types, as shown in Fig. 1:

  • Analog multimeters use a moving coil and needle to display measurements.

  • Digital multimeters are a standard multifunction digital measuring device that provides numeric readings on a digital screen with higher precision.

Fig. 1 Difference Between Analog Multimeter (Model: 72-8170 Multimeters &Amp; Clamp Meters by Tenma) and Digital Multimeter (Model: FLUKE 115 Multimeters &Amp; Clamp Meters by Fluke Corporation) Source: Oemsecrets

Additionally, some multimeters feature autoranging, which automatically selects the appropriate measurement range, making it easier to get accurate readings. This is especially helpful when you don't know the expected value of voltage, current, or resistance beforehand.

In contrast, manual ranging multimeters require setting the measurement. You must know or guess the approximate value of the measured parameter and switch ranges until you find the correct one. This can be time-consuming and lead to inaccurate readings if the wrong range is selected.

Resolution and accuracy are two necessary specifications to consider when selecting a multimeter. Production facilities and laboratories require superior accuracy and finer resolution, but they come at a higher cost. For general home use, simpler multimeters are sufficient and more affordable.

Key Components of a Multimeter

The key components of a multimeter, as shown in Fig. 2, include:

  • Display

  • Selection knob

  • Ports

  • Leads

D03124 Multimeters &Amp; Clamp Meters by Duratool

Fig. 2 Key Components of a Multimeter (Model: D03124 Multimeters &Amp; Clamp Meters by Duratool) Source: oemsecrets

Display

Shows measurement readings, typically on an LCD screen for digital models or a needle and scale for analog types.

Selection Knob (Dial)

The selection knob on a multimeter is used to choose the electrical parameter you want to measure, and it features various symbols representing these functions, as shown in Fig. 3.

72-7765 Multimeters & Clamp Meters by Tenma

Fig. 3 Selection Knob Featuring Various Symbols in Multimeter (Model: 72-7765 Multimeters &Amp; Clamp Meters by Tenma) Source: oemsecrets

Common symbols on the knob include:

  • V with a straight line (-): DC voltage

  • V with a wavy line ($\sim$): AC voltage

  • A with a straight line (-): DC current

  • A with a wavy line ($\sim$): AC current

  • Ω (Omega symbol): Resistance

  • Diode symbol (a triangle pointing to a line): Diode test

  • Sound wave or buzzer icon: Continuity test

  • $||$ : Capacitance

  • Hz: Frequency measurement

  • hFE: Transistor gain test

Ports

They serve as connectors where the test probes (leads) are plugged in. They usually include a common (COM) port and others for voltage, current, and resistance measurements.

Leads

All multimeters come with two leads: a black lead, which connects to the common or ground terminal (COM), and a red lead, which connects to the positive terminal or measurement input, ensuring correct polarity for accurate readings. In compact models, leads may be fixed but are usually detachable. The leads end with metal probes for contact with the circuit.

Note: When using a multimeter, it's important to avoid touching the metal tips of the probes. Beyond accuracy, touching the probe tips can also pose a safety risk, especially when working with live circuits. If the insulation is damaged or your fingers slip, there is a potential for electric shock or short circuits. Therefore, always hold the probes by their insulated handles.

A Digital Multimeter to Consider

Fluke 87V MAX True-RMS Digital Multimeter

The Fluke 87V MAX True-RMS Digital Multimeter is a rugged measuring instrument designed for demanding fields like manufacturing, energy, and heavy industry. The extreme durability features (IP67 rating, 4-meter drop resistance) and wide temperature range (-40°C to +55°C) are essential for technicians working in conditions where equipment might be exposed to challenging environments.

The true-RMS measurement capability is important, as many of today\'s electronic devices and variable frequency drives create non-linear signals that average-responding meters can\'t measure accurately.

The measurement capabilities are up to 1,000 V AC/DC, 10 A (20 A for 30 seconds), resistance up to 50 MΩ, capacitance up to 9999 μF, frequency up to 200 kHz, and temperature from -200°C to +1090°C. Hence, it is an accurate all-in-one tool, reducing the need for multiple instruments. The built-in temperature function with included thermocouple is particularly convenient.

The 87V MAX captures min/max/avg values with ultra-fast 250 μs peak detection, perfect for spotting anomalies in electrical systems without constant monitoring. It features a low-pass filter that removes high-frequency noise from VFDs, enabling accurate measurement.

The user-friendly display with backlight and high resolution improves working convenience, while the 800-hour battery life minimizes downtime and maintenance. The safety ratings (CAT IV 600V/CAT III 1000V) are essential for protecting users when working on industrial equipment, building infrastructure, or utility connections where voltage spikes can occur.

Overall, these features justify the Fluke 87V MAX as a premium instrument for professionals who require reliability, accuracy, and durability in demanding work environments.

Summarizing the Key Points

  • Multimeters are essential tools for electrical measurement, including voltage, current, and resistance, and they are used to diagnose issues in electrical circuits effectively.

  • They can be categorized into analog and digital types; digital multimeters offer higher precision and convenience, while analog models use a mechanical dial for readings.

  • Key features of multimeters include a user-friendly display, durable construction, multiple measurement ports, and enhanced safety ratings, ensuring both ease of use and reliability for professionals.

  • The Fluke 87V MAX stands out for its true-RMS capability, allowing > accurate readings of non-linear signals and making it ideal for > use in various demanding industrial environments.

Reference

Karataev, S. S., & Borisov, A. I. (2022). Modern structure and innovative efficiency of special equipment for analyzing semiconductor devices. Journal of Physics Conference Series, 2373(7), 072036. https://doi.org/10.1088/1742-6596/2373/7/072036

Sardjono, H., Wijonarko, S., & Wahono, D. R. (2021). Improved the quantity of DMM calibration services by speeding up the quality of the measurement method. IOP Conference Series Earth and Environmental Science, 926(1), 012057. https://doi.org/10.1088/1755-1315/926/1/012057

Petrovic, P. (2004). New digital multimeter for accurate measurement of synchronously sampled AC signals. IEEE Transactions on Instrumentation and Measurement, 53(3), 716--725. https://doi.org/10.1109/tim.2004.827313

Sevgi, L. (2007). Digital Multi-Meters and Basic Measurements. IEEE Antennas and Propagation Magazine, 49(4), 232--237. https://doi.org/10.1109/map.2007.4385653

Oemsecrets. (n.d.-a). Fluke 87V MAX - Compare distributor prices & inventory | oemsecrets.com. oemsecrets.com. https://www.oemsecrets.com/compare/Fluke%2087V%20MAX