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 unit’s 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. FEATURES DMS-20RM rms voltmeters are available in a choice of three input ranges: 20Vac (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 Two operating-supply options: 85-264Vac, or +10-40Vdc measure and accurately display the true-rms value of triangle waves, square waves, or 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-fi lter case Fully encapsulated plastic package measures 1.38” x with a built-in bezel; these meters are fully encapsulated to make them moisture and vibra- 0.88” (35mm x 22.4mm) tion resistant. Their miniature size is perfect for high-end consumer electronics, laboratory 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 FUSED AC POWER FUSED AC POWER SUPPLY +10-40Vdc SUPPLY - DC POWER 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 4

DMS-20RM Series True-rms ac Voltmeters with Isolated Inputs Performance/Functional Specifi cations ORDERING INFORMATION Typical at TA=+ 25ºC 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. Accuracy ➀ ±0.4%FS ±2 counts See www.murata-ps.com/dpm-availability for model-specifi 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 qualifi ed technical personnel. Temperature Drift (0 to 60ºC) ±0.2 ±0.4 Counts/ºC 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 — kΩ sion rms-to-dc converter and a high-precision voltage reference to DMS-20RM-2 — 200 — kΩ measure and display the rms value of complex ac waveforms. Please DMS-20RM-3 — 266 — kΩ note, the rear-mounted potential transformer is used to isolate the Power Supply Voltage (TB1) input signal being measured (TB2) from the ammeter’s operating power DMS-20RM-X-AC1 85 — 264 Vac/47-63Hz source connected to TB1. Do not pass any conductors through this transformer’s center hole as this will introduce signifi cant measure- DMS-20RM-X-DC2 +10.0 — +40.0 Vdc ment errors. Power Supply Current (TB1, ➁) 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 DMS-20RM-X-DC2 — 10 15 mAdc or application-mandated requirements pertaining to the user’s specifi c 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” suffi x) are not polarity Screw Tightening Torque 2.2 lb·in (0.25 N·m) ±20% sensitive, that is, they have no “AC LO” or “AC HI” designations. Also, ac-powered models do not include or require a connection to earth/ Rated Voltage 300Vac chassis ground. DC-powered models (“-DC2” suffi x) are reverse-polarity Display protected, and must be connected as shown in Figure 2 for proper Display Type and Size 3½ Digit LED, 0.37”/9.4mm high operation. Overrange Indication “1___” DMS-20RM voltmeters are not internally fused. Terminal block TB1 is to be used only for powering the power meter’s internal circuitry; it must Decimal Point Fixed, model dependent (see full-scale input voltage above) not be used to supply power to external loads. The supply wires feeding 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 ºC Wire insulation must be stripped to within ±10% of the stated dimen- Storage Temperature -40 — +75 ºC sions, and wires should be inserted into TB1 such that their insulation Humidity (non-condensing) 0 — 85 % is not pinched by the screw terminal. See the Functional Specifi cations section of this data sheet for wire sizes and tightening torque for TB1’s 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 qualifi 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 ➀ Specifi 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 Specifi 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. ➁ Specifi ed maximum power supply currents are steady state; larger surge currents can occur at calibration, setup, or any other technical issue pertaining to DMS-20RM initial application of power. ac voltmeters. www.murata-ps.com/support MPM_DMS-20RM.B01 Page 2 of 4

DMS-20RM Series True-rms ac Voltmeters with Isolated Inputs MECHANICAL SPECIFICATIONS L1 is a step-down potential transformer. 2.01 Do not insert any wires through L1's center hole. (51.1) See Figures 1 and 2 for typical connection diagrams. 1.00 (25.4) 0.040 (1.02) 1.30 0.800 0.040 0.040 (33.0) (20.3) (1.02) (1.02) 1.38 0.880 (35.1) (22.4) 1.600 (40.6) FRONT VIEW BACK VIEW A B TB1 - Power Supply CCCAAALLL... TB2 - Input Signal RECOMMENDED DRILL AND PANEL CUTOUT www.murata-ps.com/support MPM_DMS-20RM.B01 Page 3 of 4

DMS-20RM Series True-rms ac Voltmeters with Isolated Inputs Panel Installation All connections to DMS-20RM ac voltmeters must be made after the meter Following the four-step sequence shown in Figure 3 — being careful not to is securely attached to the panel, with all associated ac supply power apply excessive force or twisting motions — insert the DMS-20RM into the sources de-energized (off). The installed wire positions should be such that panel opening. When using the DMS-BZL4-C, install its sealing gasket so it minimal forces are applied to terminal blocks TB1 and TB2. In high-vibration is positioned between the voltmeter’s front fl ange and panel front surface environments, proper strain reliefs must be used for all wiring. (see Mechanical Specifi cations). Be sure to use and securely tighten all four screws supplied with the bezel assembly. To ensure a secure panel-mount installation, MPS recommends using the DMS-BZL4-C bezel assembly (with sealing gasket) supplied with each DMS- 20RM voltmeter. See the ‘Mechanical Specifi cations’ section for detailed cutout and voltmeter dimensions. Step 1. Step 2. Step 3. Step 4. Figure 3. Panel Installation This product is subject to the following operating requirements Murata Power Solutions, Inc. and the Life and Safety Critical Application Sales Policy: 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A. Refer to: http://www.murata-ps.com/requirements/ ISO 9001 and 14001 REGISTERED Murata Power Solutions, Inc. makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. The descriptions contained herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without notice. © 2015 Murata Power Solutions, Inc. www.murata-ps.com/support MPM_DMS-20RM.B01 Page 4 of 4