DC Panel Meters Display Voltage, Current and Power

Murata Power Solutions has introduced its DCM20 series of multifunction panel meters. For DC systems, these meters measure DC voltage and current, calculate power up to 96 kW, and display values either manually selected or continuously cycling. The miniature panel-mount product provides an input voltage range of 0.5 VDC to 72 VDC, with 10 mV of resolution. The meter also supports current measurement ranges from 5 A to 1,200 A when used with an external user-supplied resistive shunt. Targeted for use in 12 V, 24 V or 48 V systems, out-of-the-box accuracy of the product is +/-1 % for voltage and +/-2 % for current.
Packaged in a rugged, one-piece polycarbonate housing, with dimensions of 2.1″  x 1.43″ or 53.3 mm x 36.3 mm, the DCM20 fits in ‘0U’ and ‘1U’ racks making it well-suited for laboratory instrumentation as well as industrial and telecom equipment. Threaded mounting studs and caged terminal blocks for application wiring ensure reliable operation in harsh environments.

Applications for the product include, but are not limited to, real-time monitoring and display of DC power in telecom power distribution systems, battery management/backup systems, laboratory instrumentation and alternative energy and marine installations.

The DCM20 features a large (0.36″ /9.2 mm) bright red display easily readable at 15 feet (5 m), with green or blue displays a future option. A front-panel capacitive touch sensor is incorporated for selection of operating mode, avoiding wear-out issues possible with a membrane of other mechanical switches. Using the touch sensor control, the user may configure the unit to display voltage, current or power, or set the unit to continually cycle between the three measurements.

The unit can be self-powered from the measured voltage or powered separately from an external power supply, which can range from 9 VDC to 72 VDC. When self-powered, the input voltage range that can be measured is 9 VDC to 72 VDC and when externally powered the lowest measurable input voltage extends down to 0.5V. Current consumption of the DCM20 is generally negligible compared with the measured current being typically 6 mA at 12 V and only 2 m A at 72 V input.

A DIP switch on the DCM20 allows selection of 16 different full-scale current readings from 5 A to 1,200 A providing compatibility with a wide range of external shunt resistors, available both from Murata and other manufacturers. A fine adjustment potentiometer is also provided to calibrate the unit to compensate for shunt resistor tolerance for improved system measurement accuracy. The external shunt resistor may be placed in either the ‘high’ or the ‘low’ side of the power system, as the DCM20 has a common-mode voltage range of 72 V. A jumper is available to set where the voltage is actually measured, either remotely or at the shunt resistor. In this way, high or low side current sensing is practical and power measurement can exclude losses in wiring and the shunt resistor itself.

Murata Power Solutions | www.murata-ps.com

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