By Robert Green
More than perhaps any other instrument category, digital multimeters or DMMs come in a wide range of shapes and sizes. DMMs intended for use in the field emphasize portability and battery operation so service technicians and maintenance personnel can quickly and easily make basic voltage, current and resistance measurements as they go from location to location. For these applications, resolution, accuracy, measurement speed or connection to a computer are less important than battery life, durability and size.
As you might expect, benchtop multimeters are larger than handheld DMMs since they are intended for use on a designer’s bench or in an automated system test rack. Bench DMM users include engineering educators, researchers, product designers and all types of test engineers. Here’s where sensitivity, accuracy, wide measurement range, maximum functionality, measurement speed and connectivity to a personal computer come into play.
Bench DMMs have all of these capabilities and offer resolution from 5½-digits to 8 ½-digits -- well beyond the typical 3½-digit to 4½ -digit resolution of handheld DMMs. Bench DMMs can achieve sensitivities as low as 100nV, 0.1µΩ, and 1pA compared with high-end handheld DMMs with sensitivities of 10µV, 0.1Ω, and 0.01µA. A good handheld DMM’s DCV accuracy is 0.05%, while benchtop DMMs can achieve 0.0025% DCV accuracy and better.
Bench DMMs are often used for automated testing and require an interface that enables a PC to control the DMM and send and receive data. Automated testing often requires fast measurement rates and the ability to sample complex waveforms, like what’s show below. None of these capabilities are required by a maintenance technician whose job is to keep electrical systems operational. However, these benchtop features are vital for researchers, designers and test engineers.
Both handheld and bench multimeters serve specific applications and therefore offer much different sets of features and capabilities. For us at Tektronix and Keithley, our focus is on serving the needs of researchers, designers, and test engineers and we’re proud to offer the industry’s widest range of bench and system DMMs. With models spanning 5½-digit resolution to 8½-digit resolution, you’re bound to find an instrument that fits your needs. Learn more at https://www.tek.com/digital-multimeter.