DCM20 Series www.murata-ps.com Three-Function DC Power Meters PRODUCT OVERVIEW Murata Power Solutions DCM20 series DC power meters display the most critical mea- surements in DC-powered equipment: voltage, amperage and power. A front panel selector- switch provides two modes of operation: a fixed reading of any of the three parameters, or a continuous cycling through all three measurements. In fixed-reading mode, the function to be displayed (V/A/W/kW) is selected by a capacitive touch sensor, avoiding the wear-out issues often seen with membrane or other mechanical control switches. The DCM20 typically requires 6 mA of operating current at a supply voltage of 12 VDC, and only 2 mA at 72 VDC. This feature allows it to be added to existing systems with minimal electrical loading effects. The DCM20 can be powered from a DC power supply ranging from 9 to 72 VDC. The meter FEATURES supports two fundamental voltage measurement configurations. In the first configuration, Displays DC volts, amperes, watts and kilowatts. the DCM20 is powered from the DC power supply line which it is monitoring. When used in Two display modes: continuous auto cycling or fixed. this way, it can provide voltage measurements in the range of 9 - 72 VDC, as it is unpow- 9 - 72 VDC voltage operation. ered at lower voltages. The DCM20 may also be configured such that it is powered from a 0.5 - 72 VDC voltage measurement range. separate power supply than that which is monitoring. When used in this way, it can support voltage measurements over the entire 0.5 to 72 VDC range. 0 -1200 A current measurement range (dependent on external shunt). For current and power measurements, DCM20 series DC power meters require the use of 0 - 96 kW power measurement range. an external shunt resistor. The DCM20s wide common-mode input range (0 to 72 V) sup- Supports both high-side and low-side current monitoring. ports both high-side and low-side current sensing in a variety of applications. A 4-position Long-life contactless touch-sensor function selector DIP switch supports field selection of 16 shunt calibration factors. Additionally, a 12-turn switch. trim potentiometer is also provided on the rear of the meter to support precision field Low current consumption (< 10 mA at 12 VDC). calibration of the meter to the actual shunt value. Internal self-resetting fuse A large (0.36 in/9.2 mm), bright LED display makes DCM20 DC power meters easily One-piece polycarbonate housing fits 0U & 1U racks. readable from as far as 15 feet (5 meters). All units are packaged in a one-piece, vibration Compact surface mount design occupies minimal panel resistant, polycarbonate housing that can be installed in 0U rack components and vertical space. rack spaces as small as 1U. Their miniature size is perfect for laboratory instrumentation, Bright LED-display with four function annunciators. alternative energy applications, standby power supplies and any other products that require Choice of red, green, or blue display. precise monitoring of DC voltage, current, and power. SIMPLIFIED SCHEMATIC DIAGRAM DCM20 DISPLAY CURRENT-LIMITED +5 V EXTERNAL POWER SOURCE DC-DC CONVERTER 5 V + VOLTS AMPS WATTS kW TB1 ADC THERMAL 9 72 (VOLTAGE) FUSE VDC J1 +V 1 3 2 V 2 1 MICROCONTROLLER ADC +IN 3 (CURRENT) IN 4 + + SEL EXTERNAL SIGNAL SHUNT SHUNT TRIM CONDITIONER TOUCH ADJUST SENSOR SHUNT RANGE SELECTOR SWITCH For full details go to www.murata-ps.com/rohs Figure 1. Simplified Schematic www.murata-ps.com/support MPM DCM20Series.A01.D5 Page 1 of 6DCM20 Series Three-Function DC Power Meters Performance/Functional Specifications Typical at TA = +25C , V+ = 12 VDC unless otherwise specified Measurement Limits Min Typ Max Units TECHNICAL NOTES DC Voltage (A) 0.5 V 72 V DC DC Current (B) IMPORTANT To ensure safe and reliable operation, DCM20 power Range 1 - 10 m external shunt -5 5 A DC meters must be installed and serviced by qualified technical personnel. Range 16 41.67 external shunt -1200 1200 Contact Murata Power Solutions if there is any doubt regarding their Current Shunt Differential Voltage installation or operation. -100 +100 mV DC Range (C) 1. Measurement Type: DCM20 series multifunction DC power meters Current Shunt Common-mode Voltage 0 72 V Range (D) employ precision ADCs and a low-power microcontroller to measure and Current Fine Trim Range using Trim display DC voltage, current and power. The choice of measurement is 1% Potentiometer selectable through the front panel. The meters measure DC current using Power an external series shunt resistor which is inserted into the circuit to be Watts Display Mode 0 9999 W DC measured. Because the DCM20 has a wide common-mode input range Kilowatts Display Mode 0 96 kW DC (0 - 72 VDC), the shunt resistor may be inserted into either the high-side Performance (supply) or the low-side (return) of the circuit being monitored. Display Update Rate 2.5 updates/sec. Voltage Accuracy 1% 2% DC Voltage may be monitored either at the meters +IN (TB1-3) input % Full- Current Accuracy 2% 3% terminal or at the meters +V (TB1-1) power input terminal, based on scale Power Accuracy 2% 3% the setting of jumper block J1. The choice of voltage monitoring input is Temperature Drift (0 - 60) +/- 0.5 Counts/C selected based on the application requirements. Zero Current Reading (within 1 sec.) +/- 4 Count Operating Supply Voltage 9 72 V DC The DCM20 derives its DC power measurement by multiplying the Operating Supply Current (E) measured current by the measured voltage. Power is always reported 12 V operation 6 10 mA as a positive quantity, regardless of the polarity of the measured current. 72 V operation 2 5 (Power = Voltage Current ). Display 4 Digit LED, 9.14 mm (0.36 in) Height 2. Basic Operation: Upon first application of power to the meter, the unit Display Type and Size 4 LED Annunciators (Volts, Amps, will first perform a self-test routine and then continuously display DC Watts, kW) volts with the VOLTS LED annunciator illuminated. The display will remain Over-range Indication Flashing Display in the VOLTS mode as long as the front panel SEL button is not touched. Decimal Point Selection Automatically Set After the unit powers up to normal operation in the VOLTS reading mode, TB1 Terminal Block momentarily (approximately one second) touching the SEL button on Copper Wire Wire Size the units front panel twice in succession will cycle the display to AMPS, 14-24 AWG Insulation Strip Length 6mm (0.24 in) and then to WATTS (or kW, depending on the power measurement value). Screw Tightening Torque 4.6 in - lb (0.51 N-m) Momentarily touching SEL a third time will return the display back to Physical/Environmental the VOLTS reading mode. Holding the SEL button down for 5 seconds Operating Temperature 0 +60 C will place the unit in a continuous auto-cycling mode, and the display will Storage Temperature -40 +75 C repetitively scroll through all three measurements, with each measure- Humidity (non-condensing) 0 85 % ment remaining displayed for 3 seconds. Dimensions See figure 6 Unit Weight: 1.02 oz / 29g When the continuous auto-cycling mode is initially selected, the unit will Net Package Weight: 12.28 oz / 348g briefly display Auto On before continuous cycling begins. Momentarily Weight Gross Package Weight: 22.05 oz / 625g touching the SEL button again will cause the unit to briefly display Auto OFF before it returns to the fixed VOLTS reading mode. Hex Nut Tightening Torque 20 in - oz (0.14 N-m) The power-up default display mode (Volts/Amps/Watts/Auto-cycle) may (A) Voltage measured across +V (TB1-1) and V (TB1-2) OR +IN (TB1-3) and V (TB1-2) terminals. be selected by simply leaving the DCM20 in a given display mode for 60 (B) Current measurement range dependent on external shunt selection. (C) Applied to +IN (TB1-3) and IN (TB1-4) terminals. seconds or more. The next time the meter powers up, it will do so in the (D) Voltage applied across +IN (TB1-3) and V (TB1-2) terminals. new default mode. The default mode may be reset by selecting a new (E) Current drawn by +V (TB1-1) terminal when operating voltage applied across +V (TB1-1) and operating mode and leaving the meter in that mode for 60 seconds or V (TB1-2) terminals. longer. 3. Calibration: The DCM20s voltage measurement function is factory- ORDERING INFORMATION calibrated and cannot be field-calibrated. Because the meter is designed DCM20-1-DC5-R-C (Red Display) to work with a wide range of shunt resistors for current measurement, DCM20-1-DC5-G-C* (Green Display) however, field configuration and fine adjustment of the current measure - DCM20-1-DC5-B-C* (Blue Display) ment function is supported. The DCM20s shunt scaling factor is selected *Consult factory for availability by a 4-position DIP switch SW1 on the rear of the unit (refer to figure 9, Mechanical Specifications). A total of 16 ranges are supported. Table 1 lists supported current ranges and their associated switch settings, and also includes recommended Murata shunt resistors for selected ranges. Additionally, a trimmer potentiometer on the rear of the unit supports fine adjustment of the shunt scaling factor to accommodate tolerance errors www.murata-ps.com/support MPM DCM20Series.A01.D5 Page 2 of 6