Self-Powered LED Meter displays AC line frequency.

Press Release Summary:

Designed to measure and display AC mains frequencies from 45–65 Hz, DMR20-1-FM-R-C features 4-digit LED display with out-of-range indication and 0.01 Hz resolution. This round, self-powered, 2-wire, digital panel frequency monitor operates from 85–264 Vac and employs quartz crystal-controlled, MCU-based timing circuitry. With seamless construction on all sides, housing provides protection to IP67/NEMA 6 and supports mounting in industry-standard, oiltight, 1.2 in. round panel cutout.

Original Press Release:

Self-Powered LED Meter Displays AC Line Frequency

Murata announces the third generation of the DMR20 series of round, miniature digital panel frequency monitors. Designed to measure and display AC mains frequencies in the range of 45 to 65 Hertz, over an input voltage of 85 to 264 VAC, the monitor is suitable for mounting in an industry-standard “oiltight” 30 and 30.5 mm / 1.2 inch round panel cutout.

The DMR20-1-FM-R-C frequency monitor is a self-powered, 2-wire meter that does not require any additional external power sources. Equipped with a quartz crystal-controlled microcontroller-based timing circuitry, this monitor is a companion product to Murata Power Solutions' AC voltmeter, model number DMR20-1-ACV-R-C.

The meter has a display resolution of one hundredth of a Hertz (0.01Hz) from 45 to 65 Hertz, making it an attractive replacement for outdated analog frequency meters and meaning that no additional components or separate power supply is required for the unit.

The unit features a rugged housing with seamless construction on all sides, providing protection to IP67 / NEMA 6 specifications for dust, dirt, and moisture. Typical applications include use in industrial and consumer backup generators, marine instrument panels, power distribution units (PDUs), off-grid power generation, portable generators, utility test sets, and as a replacement for old analog “needle-style” frequency meters.

The DMR20 can operate from -25 to +60°C.

“Murata’s DMR20-1-FM-R-C ac line frequency monitor is the third model in a new line of low-cost, LED-display, digital panel meters designed to fit standard 1.2 inch round switch cutouts. Its rugged polycarbonate case offers excellent resistance to moisture, dust, and vibration, making it ideal for applications where protection from harsh environments is required,” says Roy Cabral, Product Marketing Manager, Murata Power Solutions.


Self-powered from 85 to 264Vac / 45-65Hz supplies

0.01Hz resolution & quartz crystal accuracy and stability

Installs in "oiltight" 1.20 inch (30.5mm) round cutouts

Four-digit LED display with out-of-range indication

Self-resetting internal fuse for long-term reliability

Supplied with EPDM rubber gasket and plastic hex nut

Provides moisture ingress protection to IP67/NEMA 6

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