DMS-20RM Series www.murata-ps.com True-rms ac Voltmeters with Isolated Inputs Murata Power Solutions DMS-20RM series are four-wire, self-contained ac voltmeters that measure and display the true-rms values of complex ac waveforms. Because the input circuitry is electrically isolated from the units operating power source, these voltmeters can measure signals down to zero volts. No external isolation transformers or auxiliary power supply conditioning components are required. Simply connect the input signal and a source of operating power (85-264Vac, or an optional +10-40Vdc) to the two rear-mounted terminal blocks and the unit is fully operational. DMS-20RM rms voltmeters are available in a choice of three input ranges: 20Vac FEATURES (with 0.01V resolution) 200Vac (0.1V resolution) and 0-300Vac (1V resolution). An input Measures the rms value of complex ac voltages frequency range of 47-1kHz makes these voltmeters ideal for all ac voltage monitoring Three input ranges: 20Vac, 200Vac and 300Vac applications. And, unlike conventional, average-responding products, these meters can measure and accurately display the true-rms value of triangle waves, square waves, or Two operating-supply options: 85-264Vac, or +10-40Vdc other irregularly shaped waveforms with 0.4% full-scale accuracy. Input circuit fully isolated from operating power supply The large (0.37/9.4mm), bright red LED display makes the DMS-20RM ac voltmeters 47-1kHz input frequency range easily readable from as far as 12 feet (4 meters). All units are packaged in a red- lter case with a built-in bezel these meters are fully encapsulated to make them moisture and vibra- Fully encapsulated plastic package measures 1.38 x tion resistant. Their miniature size is perfect for high-end consumer electronics, laboratory 0.88 (35mm x 22.4mm) instrumentation, alternative power generators and other products requiring precise ac line Large, easy-to-read, red LED display is visible from 12 monitoring. feet (4m) TYPICAL WIRING DIAGRAMS FUSED AC POWER FUSED FUSED AC POWER SUPPLY + 10-40Vdc - DC POWER SUPPLY SUPPLY A B A B A B TB1 TB1 TB1 TB2 TB2 TB2 Figure 1B. Powered by and measuring the same AC power source. AC VOLTAGE AC VOLTAGE TO BE MEASURED TO BE MEASURED Figure 1A. Figure 2. Powered by AC supply while measuring separate AC signal. Powered by DC power supply while measuring AC signal. For full details go to www.murata-ps.com/rohs www.murata-ps.com/support MPM DMS-20RM.B01 Page 1 of 4DMS-20RM Series True-rms ac Voltmeters with Isolated Inputs Performance/Functional Speci cations ORDERING INFORMATION Typical at TA=+ 25C with 60Hz sine-wave input, unless otherwise noted DMS-20RM-1-AC1-R-C 0 to 19.99Vac, AC Powered Full-Scale Input Voltage (TB2) Min. Typ. Max. Units DMS-20RM-2-AC1-R-C 0 to 199.9Vac, AC Powered DMS-20RM-1 0 19.99 Vac DMS-20RM-3-AC1-R-C 0 to 300Vac, AC Powered DMS-20RM-2 0 199.9 Vac DMS-20RM-3 0 300 Vac DMS-20RM-1-DC2-R-C 0 to 19.99Vac, DC Powered Frequency Range 47 60 1000 Hz DMS-20RM-2-DC2-R-C 0 to 199.9Vac, DC Powered Performance DMS-20RM-3-DC2-R-C 0 to 300Vac, DC Powered Sampling Rate 2.5 reading per second A DMS-BZL4-C bezel assembly with sealing gasket is supplied with each meter. 0.4%FS 2 counts Accuracy See www.murata-ps.com/dpm-availability for model-speci c availability. with 60Hz sine wave input IMPORTANT To ensure safe and reliable operation, DMS-20RM ac Measurement Type rms responding, Crest Factors of 1-5 voltmeters must be installed and serviced by quali ed technical personnel. Temperature Drift (0 to 60C) 0.2 0.4 Counts/C Contact Murata Power Solutions if there is any doubt regarding installation Zero-Volt Reading (within 30 sec.) -001 000 001 Counts and/or operation. Breakdown Voltage, TB1 to TB2 2000 Vdc TECHNICAL NOTES Input Impedance 1. Measurement Type: DMS-20RM series ac voltmeters employ a preci- DMS-20RM-1 20 k sion rms-to-dc converter and a high-precision voltage reference to DMS-20RM-2 200 k measure and display the rms value of complex ac waveforms. Please DMS-20RM-3 266 k note, the rear-mounted potential transformer is used to isolate the Power Supply Voltage (TB1) input signal being measured (TB2) from the ammeters operating power source connected to TB1. Do not pass any conductors through this DMS-20RM-X-AC1 85 264 Vac/47-63Hz transformers center hole as this will introduce signi cant measure- DMS-20RM-X-DC2 +10.0 +40.0 Vdc ment errors. Power Supply Current (TB1, ) 2. Wiring: All power supply and input signal wiring must be rated for the DMS-20RM-X-AC1 30 50 mA/47-63Hz voltages and currents they will carry and must comply with any code or application-mandated requirements pertaining to the users speci c DMS-20RM-X-DC2 10 15 mAdc installation. Terminal Block Wiring (TB1 and TB2) 3. Power Supply Polarity, Fusing, and Grounding: As shown in Figures Wire Size 16-22AWG, Solid or stranded 1A, 1B, and 2, the two power supply inputs, TB1-A and TB1-B, on Insulation Strip Length 0.250 inches ac-powered DMS-20RM voltmeters (-AC1 suf x) are not polarity sensitive, that is, they have no AC LO or AC HI designations. Also, Screw Tightening Torque 2.2 lbin (0.25 Nm) 20% ac-powered models do not include or require a connection to earth/ Rated Voltage 300Vac chassis ground. DC-powered models (-DC2 suf x) are reverse-polarity Display protected, and must be connected as shown in Figure 2 for proper Display Type and Size 3 Digit LED, 0.37/9.4mm high operation. DMS-20RM voltmeters are not internally fused. Terminal block TB1 is to Overrange Indication 1 be used only for powering the power meters internal circuitry it must Decimal Point Fixed, model dependent (see full-scale input not be used to supply power to external loads. The supply wires feeding voltage above) these power meters must be fused with a 0.25A/250V time delay/time Physical/Environmental lag fuse, in accordance with applicable regulatory codes. Operating Temperature -25 +60 C Wire insulation must be stripped to within 10% of the stated dimen- Storage Temperature -40 +75 C sions, and wires should be inserted into TB1 such that their insulation is not pinched by the screw terminal. See the Functional Speci cations Humidity (non-condensing) 0 85 % section of this data sheet for wire sizes and tightening torque for TB1s Dimensions Model dependent see product datasheet. screw terminals. Weight: 1.3 Ounces (36 grams) nominal 4. Calibration: Periodic recalibration of DMS-20RM voltmeters is not required under normal, indoor operating environments. If calibration is necessary, it should only be performed by quali ed technical personnel. Calibration is performed with potentially lethal voltages applied to the DMS-20RM and its associated wiring. A plastic, fully-insulated adjust- ing tool must be used to access the recessed calibration potentiometer Speci ed accuracy applies to inputs with crest factors (CF) up to 2.0, where CF = Vpeak/Vrms. located on the back of the unit (see Mechanical Speci cations). Contact Crest factors of 2 to 5 introduce an additional error of 3% of full scale. Voltmeters are calibrated Murata Power Solutions if additional information is required regarding with a near full-scale, 60Hz sine-wave input. calibration, setup, or any other technical issue pertaining to DMS-20RM Speci ed maximum power supply currents are steady state larger surge currents can occur at initial application of power. ac voltmeters. www.murata-ps.com/support MPM DMS-20RM.B01 Page 2 of 4