Features
- 0.2, 2, 20, 200, 300 & 600V AC or AC+DC voltage ranges
- 2, 20, 200 mA & 5A AC or AC+DC current ranges
- Accuracy to 0.03% of full scale, 0.1% to 100% of FS, 10 Hz to 5 kHz
- 0.03% accuracy of full scale at crest factor to 3.0
- True RMS AC measurement with crest factor of 3.0 at full scale
- Measurements from 0.1% to 100% of full scale
- AC or DC coupling for signals from DC to 5 kHz
- Fast response: reading in 0-16.7 ms after each signal cycle to full accuracy
- All input ranges are user selectable and factory calibrated
- Up to 60 conversions per second, Ideal for peak or valley capture
- Digital span adjust from 0 to ±99,999, zero adjust from -99,999 to +99,999
- Front panel scalable to ±99,999 for use with current shunts
- 1/8 DIN size with bright red or green 0.56" (14.2mm), high LED digits
- Power 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac (isolated)
- Operating temperature from -40°C to 70°C (-40°F to 158°F)
- Wide choice of Plug-in-Play options:
- 2 or 4 relays, mechanical or solid state, for alarm or control (isolated)
- 1 or 2 Analog output, 4-20 mA, 0-20 mA, 0-10V, or -10V to +10V (isolated)
- Communications: Ethernet, WiFi, USB, RS232, RS485 (isolated)
- Extended DPM allows up to 180 data points for custom curve linearization
Certificates of Compliance
The Laureate™ 1/8 DIM Panel Meter for True RMS
is a 60,000 count panel meter with exceptional performance at half the price of a bench top meter. It can measure true RMS voltages or current of AC signals where there is considerable distortion of the waveform, such as rectifier outputs or waveforms chopped by an SCR, TRIAC or transistor circuit, as illustrated.- True RMS readings in 0-16 ms after completion of one input signal cycle allow anomalies to be detected and alarmed before they become expensive problems. Fast On/Off control and alarm can be achieved with optional dual or quad relays, either contact or solid state. The meter can also capture peak and valley readings that occur at the nominal rate of 50/60 Hz.
- Accuracy is 0.03% of full scale with the meter's standard 1 Megohm input resistance, signals from DC to 5 kHz, and signal amplitudes down to 0.5% of full scale. A version with 10 Megohm input resistance is available as a factory special, but decreases the maximum frequency from 5 kHz to 1 kHz for three of the voltage ranges.
The crest factor (Vp / Vrms) is 3.0 at full-scale Vrms of 20,000 counts and a Vp of 60,000 counts. The meter starts to flash overrange at 132% of full scale Vrms, at which point the available crest factor is 60,000 / 26,400 = 2.27. Meaningful readings with rated resolution continue to be obtained up to 212% of full scale Vrms (42,433 counts) for sinusoidal signals, at which point the available crest factor is 1.414. For safety reasons, the maximum RMS input signal should never exceed 600V or 5A. ETL certification is for a maximum voltage of 300 Vrms.- AC or DC coupling is jumper selectable. AC coupling is suitable for applications such as measuring the ripple on a DC power supply. Multiple integral cycles are averaged for signals above 50/60 Hz. A single cycle is captured for signals from 3 Hz to 50/60 Hz. Below 3 Hz and at DC, the capture rate is every 333 ms.
Use with current Transformers. High common mode rejection allows stable readings with current shunts located on the high side of the line. Five amp input capability allows the output of 5A current transformers to be applied directly to the meter, with no need for a stepdown transformer. The meter reading can easily be scaled for the current transformer ratio. Digital filtering is selectable for noisy signals.
All signal conditioner board ranges are factory-calibrated, with calibration factors for each range securely stored in an onboard EEPROM. These factors can be scaled via software to accommodate external shunts, enabling field replacement of signal conditioner boards without necessitating recalibration of the associated panel meter. For optimal accuracy, factory recalibration is recommended annually. All Laurel Electronics instruments undergo factory calibration using the industry-leading Fluke calibrators, which are recalibrated yearly and certified traceable to national standards, ensuring the highest level of precision and reliability.
The optional extended Laureate computer board enhances Laureate Panel Meters by displaying rates derived from successive readings and enabling highly accurate custom curve linearization. For example, it can calculate liquid volume or flow rate in a horizontal cylindrical tank using levels from a 4-20 mA transmitter. Setup is straightforward: users input up to 180 data points into a spreadsheet or text file, and the computer calculates spline-fit segments, which are then downloaded to the meter for precise operation.
The Laureate Panel Meter is easily programmed with Laurel’s free Instrument Setup Software, downloadable from our website and compatible with Windows PCs, requiring a data interface board for setup.
High read rate of up to 50 or 60 conversions per second, the Laureate™ Panel Meter uses Concurrent Slope (US Pat. 5,262,780) analog-to-digital conversion to integrate signals over a full power line cycle (50 Hz or 60 Hz). This read rate enables peak and valley capture, real-time computer interfacing, and control applications. Peak and valley values are automatically captured and can be viewed using Laurel’s free Instrument Setup Software (compatible with Windows PCs) or transmitted as serial data.
Digital signal filtering modes can be selected to ensure stable readings in electrically noisy environments.
- An unfiltered selection provides true peak and valley readings and aids in control applications.
- A batch average filter selection averages each 16 conversions.
- An adaptive moving average filter selection provides a choice of 8 time constants from 80 ms to 9.6 seconds. When a significant change in signal level occurs, the filter adapts by briefly switching to the shortest time to follow the change, then reverts back to its selected time constant. An Auto setting selects the time constant selection based on signal noise.
Two tare functions: auto-tare and manual tare. In auto-tare, an input line is grounded by an external pushbutton. In manual tare, the tare value can be entered manually via the front panel or a computer using Laurel's free Instrument Setup Software.
Peak and valley values are automatically captured. These may be displayed via a front panel pushbutton command or control signal at the rear connector, or be transmitted as serial data.
Two rear panel control Inputs (CMOS/TTL levels, logic 0 = tied to digital ground, logic 1 = open) or dry contacts that can be set to control / activate 14 meter commands.
AC Voltage
| AC Voltage FS Range |
AC Voltage to Overrange Flash |
Resolution | Input Resistance |
Error at 25°C |
|---|---|---|---|---|
| 200.00 mV | 264.00 mV | 10 µV | 1 MΩ |
± 0.03% of FS ± 2 cts, 0.1-100% of FS |
| 2.0000 V | 2.640 V | 100 µV | ||
| 20.000 V | 26.400 V | 1 mV | ||
| 200.00 V | 264.00 V | 10 mV | ||
| 300.0 V |
650 V | 0.1 V | ± 0.8 V | |
| 600.0 V* | 650 V | 0.1 V | ± 0.8 V | |
| * Range not ETL certified. For purposes of accuracy calculation, the 600V range is 2000V (20,000 counts). | ||||
| Recalibration: All ranges are calibrated at the factory. Recalibration is recommended every 12 months. | ||||
AC Current
| AC Current Range | AC Current to Overrange Flash |
Resolution | Input Resistance | Error at 25°C |
|---|---|---|---|---|
| 2.0000 mA | 264.00 µA | 0.1 µA | 100 Ω | ± 0.03% of FS ± 2 cts, 0.1-100% of FS |
| 20.000 mA | 26.400 mA | 1.0 µA | 10 Ω | |
| 200.00 mA | 264.00 mA | 10 µA | 1 Ω | |
| 5.000 A | 5.4 A | 1 mA | 0.01Ω | ± 20 mA |
| * For purposes of accuracy calculation, the 5A range is 20A (20,000 counts). | ||||
| Recalibration: All ranges are calibrated at the factory. Recalibration is recommended every 12 months. | ||||
Both AC Voltage & Current
| Display | |
|---|---|
| Readout | 5 LED digits, 7-segment, 14.2 mm (.56"), red or green |
| Range | -99999 to 99999 or -99990 to 99990 (count by 10) |
| Display Update Rate | 3.75/s at 60 Hz power, 3.1/s at 50 Hz power |
| Indicators | 1 LED lamp per relay setpoint |
| Crest factor Vp / Vrms | 3.00 at full scale range |
| Output Update Rate | |
| A-to-D rate | 60/s at 60 Hz power, 50/s at 50 Hz power |
| Signals > 50/60 Hz | 60/s at 60 Hz power, 50/s at 50 Hz power |
| Signals 3 Hz to 50/60 Hz | Same as signal frequency |
| Signals DC to 3 Hz | 3 per second |
| Maximum Signal | |
| Max applied voltage | 600 Vac for 2, 20, 200, 600V ranges, 35 Vac for 0.2V range |
| Current protection |
25x for 2 mA, 8x for 20 mA, 2.5x for 200 mA, 1x for 5A |
| Power Supply Boards (one required) | |
| Voltage, standard | 85-264 Vac or 90-300 Vdc |
| Voltage, optional | 12-32 Vac or 10-48 Vdc |
| Frequency | DC or 47-63 Hz |
| Power consumption (typical, base meter) | 1.2W @ 120 Vac, 1.5W @ 240 Vac, 1.3W @ 10 Vdc, 1.4W @ 20 Vdc, 1.55W @ 30 Vdc, 1.8W @ 40 Vdc, 2.15W @ 48 Vdc |
| Power Isolation | 250V rms working, 2.3 kV rms per 1 min test |
| Analog Output Board (one optional) | |
| Output levels | 4-20 mA, 0-20 mA, 0-10V, -10 to +10V (jumper selectable) |
| Current compliance | 2 mA at 10V ( > 5 kΩ load) |
| Voltage compliance | 12V at 20 mA (< 600 Ω load) |
| Scaling | Zero and full scale adjustable from -99999 to +99999 |
| Resolution | 16 bits (0.0015% of full scale) |
| Step function response | 80 ms to 99% of final value (typ) |
| Isolation | 250V rms working, 2.3 kV rms per 1 min test |
| Relay Output Boards (one optional) | |
| Dual magnetic relays | 2 Form C, 10A max, 440Vac or 125Vdc max, 2500VA or 300W |
| Quad magnetic relays | 4 Form A (NO), 10A max, 440Vac or 125Vdc max, 2500VA or 300W |
| Dual solid state relays | 2 Form A (NO), AC or DC, 0V - 400V, 120Ma, 35Ohms (max at On-State) |
| Quad solid state relays | 4 Form A (NO), AC or DC, 0V - 400V, 120Ma, 35Ohms (max at On-State) |
| Relay commons | Isolated commons for dual relays or each pair of quad relays |
| Relay isolation | 250V rms working, 2.3 kV rms per 1 minute test |
| Step function response | 30 ms (typ) for contact relays, 25 ms (typ) for solid state relays |
| Relay latching modes | Latching or non-latching |
| Relay active modes | Active on or off, active high or low |
| Hysteresis modes | QA passband mode, split hysteresis, span hysteresis |
| Communication Boards (one optional) | |
| Board selections | RS232, RS485 with dual RJ11 connectors, RS485 with dual RJ45 connectors, USB, Ethernet, USB-to-RS485 gateway, Ethernet-to-RS485 gateway, WiFi with built-in antenna plus USB & RS485, WiFi with external antenna plus USB & RS485 |
| Protocols | Laurel Custom ASCII (serial), Modbus RTU (serial), Modbus TCP (Ethernet or WiFi) |
| Digital addresses | 247 (Modbus), 31 (Laurel ASCII), |
| Isolation | 250V rms working, 2.3 kV rms per 1 min test |
| Signal Connections | |
 |
|
| Environmental | |
| Operating temperature | -40°C to 70°C (-40°F to 158°F) |
| Storage temperature. | -40°C to 85°C (-40°F to 185°F) |
| Relative humidity | 95% at 40°C, non-condensing |
| Protection | NEMA-4X (IP-65) when panel mounted |
| Mechanical | |
| Enclosure | 1/8 DIN, high impact plastic, UL 94V-0, color: black |
| Mounting | 1/8 DIN panel cutout required: 3.622" x 1.772" (92 mm x 45 mm). |
| Dimensions | 4.68" x 2.45" x 5.64" (119 mm x 62 mm x 143 mm) (W x H x D) |
| Maximum panel thickness | 4.5 mm (0.18") |
| Tightening Torque - Connectors | Screw terminal connectors: 5 lb-in (0.56 Nm) |
| Tightening Torque - Pawls | Digital Panel Meter Case Pawls: 5 lb-in (0.56 Nm) |
| Weight of base meter | 210 g (7.4 oz) typical (DPM, counter, timer, 6-digit remote display) |
| Weight of option boards | 30 g (1.0 oz) typical per board (analog output, relay output, communications) |
| General | |
| Programming Methods | Four front panel buttons or via Laurel's free Instrument Setup Software, which runs on a PC under MS Windows. |
| Security | Lockout options include using the front panel buttons, the free Instrument Setup Software, or a hardware jumper. |
| Warranty | 3 years parts & labor |
| Recalibration: All ranges are calibrated at the factory. Recalibration is recommended every 12 months. | |
Free Instrument Setup Software for Series 2 Laureates
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| 1/8 DIN Digital Panel Meters | DIN Rail Transmitters |
Free Downloadable Windows-based Instrument Setup (IS) software (Data Interface Board Required) for use with our programmable Digital Panel Meters, Scale Meters, Counters, Timers, Remote Displays, and Transmitters, are an easy method to set up Laureate 1/8 DIN digital panel meters, counters, timers, remote displays, and DIN-rail transmitters, as explained in the Instrument Setup Software Manual. Laureate 1/8 DIN instruments can also be set up from the front panel, as explained in their respective Owners Manuals. Instrument Setup software is of benefit whether or not the PC is connected to the instrument.
- When the PC is connected to the instrument, Instrument Setup software can retrieve the setup file from the instrument or open a default setup file or previously saved setup file from disk View Setup, then provides graphical user interface (GUI) screens with pull-down menus applicable to input, display, scaling, filtering, alarms, communications, analog output, and front panel lockouts. Fields that are not applicable to the instrument as configured are either left out or grayed out. Clicking on any item will bring up a detailed Help screen for that item. After editing, the setup file can be downloaded, uploaded to the instrument, or saved to a disk. The same setup file can then be downloaded into multiple instruments.
- When the PC is not connected to the instrument, the above GUI screens can be used to set up a virtual instrument. The setup file can then be saved to disk. Switching toView Menu then brings up a screen with the required front panel programming steps. This view can be printed out for use at the instrument site and to serve as a hard copy record.
Download Free Instrument Setup Software
Installation
Set User Account Control (UAC) of MS Windows to "Never notifiy me" so that Instrument Setup Software can create directories. The UAC change screen can be reached as follows:
- Under Windows 7, click on the Windows Start button in the lower left of the desktop and enter "UAC" in the search field.
- Under Windows 8, navigate to Control Panel, then to the "User Accounts and Family Safety" section, and click on "Change User Account Control Settings."
- Under Windows 10, click on the Windows Start button in the lower left of the desktop, then on "Settings", and enter "UAC" in the search field.
- Reboot your computer for the changed UAC setting to take effect.
RJ11-to-DB9 cable with rear view of DB9 connector to PC
RS232 cable, meter to PC, P/N CBL01
Laureate 1/8 DIN Laureate instruments must be equipped with a serial communications board and be connected to the computer via a serial communications cable. The connection can be via RS232, RS485, USB or Ethernet. Following setup, the serial communications board may be removed from the instrument if desired. The wiring of the RS232 cable is illustrated above with end views of the two connectors.
Laureate LT Series transmitters come standard with a 3-wire serial interface, which can be jumpered for RS232 or RS485.
Laureate LTE Series transmitters come standard with an Ethernet interface.
Meter Setup Screens
Click on any of the reduced screens below for a full-size screen view, then click on the Back button of your browser to return to this page. The screens examples below are for a fully-loaded Series 2 Digital Panel Meter (DPM), which is connected to the PC via RS232. If the meter is a Series 1 meter (pre-2007), this is sensed by the software, and somewhat different screens are brought up. Please see Series 1 setup screens.
Welcome Screen
From the computer desktop, click on Start > Programs > IS2 > IS2. Or click on the IS icon on your desktop. This splash screen will be displayed for three seconds. The software revision number is in the lower right.
Communications Selection Screen
Specify your desired communication protocol and the serial communications bus type, which should match the jumper setup of the instrument. Select None if the PC is not connected to the instrument.
Establish Communications Screen
If you selected RS-232, you will be asked to specify the PC Com Port and Baud Rate, which should match the jumper setup of the instrument. Click on Establish. With the right settings, the Communications Established field will light up in green, and the Meter Type will be recognized. If so, click onMain Menu.
Main Menu Screen
Click on File > Default Setup to retrieve the default setup file from disk for your type of meter. Click on File > Open Setupto retrieve a previously saved setup file from disk or on File > Save Setup to save your edited setup file to disk. Click onDPM > Get Setup to retrieve the setup file from your meter or on DPM > Put Setup to download your edited setup file into the meter.
DPM Input + Display Setup Screen
From the Main Menu, click on View > Setup, then on theInput+Display tab. You can now specify the meter hardware, signal type, display mode, and functions of control inputs A and B. Clicking on any item brings up a pull-down menu with the available choices.
DPM Scaling Setup Screen
Click on the Scaling tab, which provides three scaling methods to relate the signal to the displayed reading: 1) Scale and Offset method, 2) Coordinates of two points method, and 3) Reading Coordinates of Two Points method. The last method uses actual high and low signals, and the computer will prompt you.
DPM Filter Setup Screen
Click on the Filter tab, which allows you to specify the digital filter time constant (if any), the adaptive filter threshold, and whether Peak / Valley values are filtered or unfiltered. As for all setup screens, clicking on the F1 key while an item is highlighted brings up a Help screen for that item, as illustrated.
DPM Relay Alarms Setup Screen
Click on the Relay Alarms tab, which allows you to set up Alarms 1 and 2 for the optional dual relay output board. Clicking on any of the four numeric fields changes these to green and brings up a special field to enter the desired numeric value, which is tied to the displayed reading.
DPM Communications Setup Screen
Click on the Communications tab so set up serial communications. In particular, you can special the Serial Protocol and the meter address if multiple meters are to be addressed on the same serial data line.
DPM Analog Output Setup Screen
Click on the Analog Out tab so set up the optional analog output board. Three output ranges are selectable, the endpoints of which can be tied to user-specified High and Low readings.
DPM Lockouts Setup Screen
Click on the Lockouts tab to check off menu items which will no longer be accessible from the front panel of the meter. This will simplify meter operation and prevent unintended setup changes.
Meter Setup Utilities
DPM Front Panel Setup Screen
As an aid to programming the meter from the front panel when a serial connection is not available, you can return to the Main Menu and click on View > Menu. The required sequence of front panel screens will then be displayed. Click on any step in the sequence for the meaning of each digit, as illustrated for the FILtEr step. For a hardcopy, simply press on Print.
DPM Jumper Setup Screen
Specify your desired communication protocol and the serial communications bus type, which should match the jumper setup of the instrument. Select None if the PC is not connected to the instrument.
DPM Jumper Setup Screens
Click on any of the displayed plug-in boards, and you will be presented with the jumper positions and electrical connections for your selected board. This minimizes the need to refer to the printed manual.
DPM Commands Screen
This page allows you set up external input, serial communications, an analog output proportional to the display (optional), and lockouts for Laureate digital counters. The grayed out area at the top right of the screen applies to Laureate remote displays.
Graphical Output Screens (not available with Ethernet)
From the Main Menu, click on Readings if your PC is connected to the meter. A pull-down menu then offers three choices: List, Plot and Graph.
- List presents the latest readings in a 20-row by 10-column table. Press Pause at any time to freeze the display. This is one method to capture peak readings.
- Plot generates a plot of readings vs. time in seconds. It effectively turns the DPM-PC combination into a printing digital oscilloscope.
- Graph generates a histogram where the horizontal axis is the reading and the vertical axis is the number of occurrences of readings. The display continually resizes itself as the number of readings increases.
DPM Calibration Screens
Click on the Scaling tab, which provides three scalClick on the Scaling tab, which provides three scaling methods to relate the signal to the displayed reading: 1) Scale and Offset method, 2) Coordinates of two points method, and 3) Reading Coordinates of Two Points method. The last method uses actual high and low signals, and the computer will prompt you.
Frequency Meter Calibration Screen
Calibration of the quartz crystal of the Laureate frequency meter requires the input of a known frequency from a calibrator. Apply the frequency, then enter the frequency in Hertz. Calibration will be automatic, with storage of the calibration factor stored in non-volatile memory.
Laureate™ 1/8 DIN Case For Laureate Digital Panel Meters, Counters, Timers & Remote Displays
Key Features
- Meets 1/8 DIN Standard.
- Installs from front of panel.
- Short depth behind the panel: only 4" (102 mm) plus connectors.
- Understated 0.157" (4 mm) thick bezel.
- Meets NEMA 4X (IP-65) for high-pressure wawshdon when panel mounted.
- Screw clamps connectors meet VDE / IEC / UL / CSA safety standards.
- Rugged GE Lexan® housing material.
- Safety certified per EN 61010-1.
Dimensions
Maximum panel thickness: 4.5 mm (0.18")
Weight of base meter: 210 g (7.4 oz) typical (DPM, counter, timer, 6-digit remote display)
Weight of option boards: 30 g (1.0 oz) typical per board (analog output, relay output, communications)
Tightening Torque - Connectors: Screw terminal connectors: 5 lb-in (0.56 Nm)
Tightening Torque - Pawls: Digital Panel Meter Case Pawls: 5 lb-in (0.56 Nm)
Dimensioned CAD assembly drawings in EPRT, STEP, x_t. dwg, pdf file formats: Laureate-meter-case.zip (zipping prevents browser from opening CAD files as text files).
Panel Mounting
Slide the meter into a 45 x 92 mm 1/8 DIN panel cutout. Ensure that the provided gasket is in place between the front of the panel and the back of the meter bezel.
The meter is secured by two pawls, each held by a screw, as illustrated. Turning each screw counterclockwise extends the pawl outward from the case and behind the panel. Turning each screw clockwise further tightens it against the panel to secure the meter.
Turning each screw counterclockwise loosens the pawl and retracts it into its well. This position allows installed meter to be removed from their panel, or new meters to be installed in a panel. Do not remove the screws from their pawls. Doing so would cause the screw and pawl to fall off and likely get lost. Do not overtighten so as not to damage the plastic parts.
AC RMS Digital Panel Meter Frequently Asked Technical Questions
In Laureate AC RMS meters, a total of five AC voltage ranges are user selectable and factory calibrated, with calibration factors stored in EEPROM on the signal conditioner board. AC RMS meters come factory set for a specific range, like RMV1. To change to a different range, move jumpers on the signal conditioner board and select the new range in software, as explained in the Laureate DPM user manual. If you change the range, also change the model number on the meter label.
Laureate AC RMS meters are modular with slots for an analog output board, a choice of relay boards, and a choice of communication boards, as illustrated in our Laureates Overview web page. These boards can be ordered installed with a new meter, but they can also be purchased separately later and be simply plugged in. The presence of a new board and the type of board are automatically sensed by the meter’s firmware or by Instrument Setup (IS) software. If you change boards, also change the model number on the meter label.
True AC RMS meters are preferred because they can measure the energy content of sinusoidal or non-sinusoidal waveshapes, which can be chopped or distorted. They display the equivalent DC voltage or current that would create the same heating of resistive load. At any instant, the applied heat is V2/R or I2R, where V is voltage, I is curent and R is resistance. RMS stands for square Root of the Mean of the Squares. Lower cost AC meters use simple wave rectification and averaging to simulate RMS readings. Such similation is only accurate for perfectly sinusoidal waveforms.
A count is a unit of resolution. All ranges of Laureate AC meters go from 0 to 20,000 input counts. For example, in the Laureate 200.00 mV RMV1 range, an input count is 0.01 mV. The Laureate 600.0V RMV5 range and 300.0V RMV6 range are both based on a fictitious 2000.0V range, so an input count is 0.1V.
A display count is the resolution of the meter reading, or the step value of the least significant digits. For example, a meter reading of 465.7 is 4657 display counts. The decimal point is set separately as a decoration.
Input scaling is the process of converting the input counts to a reading in display counts. For example, to convert the 0-50.00 mV AC output of a current shunt to a 0-50.0A AC reading, use the meter’s 200.00 mV RMV1 range. 50.00 mV is then 5000 input counts. 50.0A is 500 display counts. To go from 5000 to 500, enter a scale factor (or multiplier) of 0.1 and an offset of 0.
Analog output scaling is the process of converting the meter reading to an analog output. That output can be selected as 4-20 mA, 0-20 mA, 0-10V or -10 to +10V. Simply enter the meter readings for the bottom and tops of the analog output range, and the output will be interpolated linearly between these two readings. Please see Section 17 of the Laureate DPM user manual.
Chances are that your meter is set for the factory default analog output, which is 4-20 mA, and is applying around 12V to force a current into an open circuit. To set your meter to a 0-10V or -10 to +10V analog output, set jumpers for unipolar 0-10V or bipolar -10 to +10V operation, select that range in software and scale it in software, and connect to the designated analog output pins, as explained in Section 17 of the Laureate DPM user manual.
Calibration is the process of setting the meter so that absolute readings in volts or amps are within specified tolerances of a recognized national standard. All ranges of Laureate DC input analog output boards are factory calibrated to standards of the US National Institute of Standards and Technology (NIST), with calibration factors stored in EEPROM on the board itself. This allows boards to be swapped in the field with not need to recalibrate the meter as a system. Scaling relates the meter input to the displayed reading.
Annual calibration to NIST standards can be performed by Laurel Electronics, LLC.
The highest AC RMS voltage that can be applied to a Laureate AC meter is 600.0V when the meter is set to the RMV5 range. For higher voltages, use an external step-down voltage transformer (VT) to bring the voltage to be measured to less than 600.0V (RMV5 range). A transformer also provides electrical isolation and is an important safety tool. It can have a very low power rating. For example, to measure 1000V AC in even volts, use a 2:1 stepdown transformer for an output of 500.0V, use the meter's 600.0V RMV5 range, and scale the meter with a scale factor of 0.2. This will convert the 5000 input counts for 500.0V to 1000 display counts.
Using Laureate Meters to Synchronize Two Motor Generators
Successful synchronization of two motor generators requires that the voltage outputs of the generators be close to each other, that the two frequencies be identical, and that the voltage waveshapes be in phase.
- The two voltages can be measured by two Laureate AC RMS Voltmeters, which offer 200.00 V and 600.0 V ranges. Or a single meter can be multiplexed by using an external toggle switch.
- Two frequencies A & B can be measured to six-figure accuracy by a single Laureate Dual Channel Counter, where each channel monitors a generator. The two AC neutrals must be tied to meter ground. Pressing a front-panel key toggles the reading between the channels. The meter can also display frequency A - frequency B, or frequency A / frequency B without toggling.
- Phase angle can be measured using the Laureate Phase Meter.
Using Laureate Meters and Counters to Instrument an AC Line
Why Measure AC Power?
Many AC loads, such as electrical motors, will only operate reliably if the AC line voltage and frequency are within specified tolerances; otherwise permanent damage to expensive plant equipment may occur. Drops in line voltage or frequency may indicate an excessive load and the possibility of equipment damage. Laureate meters and counters are low-cost means to instrument and alarm AC power lines with great accuracy:
- AC RMS Voltmeter and Ammeter, as documented in this page. True RMS capability allows the display of RMS voltage for non-sinusoidal waveshapes, such as square waves from a UPS. A built-in 5 A range can be used to display currents up to 5.000 A with 1 mA resolution or accept the output of 5 A current transformers. The 200.00 mV range can be used with external current shunts. With either transformers or shunts, scaling of the input current is easily accomplished via the meter's front panel pushbutton switches.
- Frequency Meter. Inverse period is used to determine AC line frequency to six-figure accuracy (60.0000 or 50.0000) in a few line cycles plus 30 ms.
- Phase Angle & Power Factor Meter. Two signals with identical periods are applied to Channels A and B. A phase angle resolution of 1%, 0.1% or 0.01% is selectable. Accuracy is .01% up to 100 Hz, .1% at 1 kHz, and 1% at 10 kHz.
CAL-Analog
Certificate of Calibration
$65.00
DLS-XLOG2
XLog2 Data logging Software
$495.00
IPC
Splashproof Cover
$55.00
CON01
CON01 Connector
$75.00
CBL01
RS232 Cable for Meters
$35.00
CBL02
USB-to-RS232 Adapter Cable
$47.00
CBL04
RS232 Cable for LT Transmitters
$47.00
CBL05
USB Data Cable for Meters
$47.00
CBL06
USB-to-RS485 Adapter Cable
$47.00
CBL07
USB Programming & Data Cable
$47.00
CBL08
RS485 Splitter Cable
$33.00CBL6
6-foot Power Cable
$41.00CBL12
12-foot Power Cable
$47.00Modular Design for Maximum Flexibility at Minimum Cost
All boards are isolated from meter and power grounds. Optional Plug-in-Play boards for communications and control include Ethernet, WiFi, serial communication boards, dual or quad relay boards, and an analog output board. Laureates may be powered from 85-264 Vac or optionally from 12-32 Vac or 10-48 Vdc. The display is available with bright red or green 0.56" (14.2mm) high LED digits. The 1/8 DIN case meets NEMA 4X (IP65) specifications from the front when panel mounted. Any setup functions and front panel keys can be locked out for simplified usage and security. A built-in 5, 10, 12, or 24 Vdc excitation supply can power transducers, eliminating the need for an external power supply. All power and signal connections are via UL / VDE / CSA rated screw clamp plugs.
The Laureate™ Series features modular design with up to 7 isolated plug-in boards, applicable to all Laureate 1/8 DIN Panel Meter.
Modular Hardware
The design of the Laureate™ Series is modular for maximum flexibility at minimum cost. All boards are isolated from meter and power grounds. The base configuration for a panel meter or counter consists of a main module (with computer and plug-in display boards), a power supply board, and a signal conditioner board. Optional plug-in-play boards include an isolated setpoint controller board, an isolated analog output board, and an isolated digital interface board. Modular design and a choice of plug-in options allow the Laureate to be customized for a broad range of applications from simple monitoring to control and computer interface. There can be up to five plug-in boards in a 1/8 DIN Laureate.
Connecting Laureate Panel Meter to a Local Area Network (LAN)
Up to 30 Laureate Panel Meter and/or LT Transmitters can be configured for RS485 and daisy-chained to an LT Transmitter using Laurel’s High Speed Ethernet-to-RS485 converter board for seamless LAN integration. Alternatively, Laurel LTE series Ethernet transmitters can connect directly to a LAN via an Ethernet cable. Setup for both configurations is streamlined using Laurel’s free Instrument Setup Software, which simplifies node discovery and transmitter configuration.
Flexible Communication Options for Panel Meter
The Laureate Panel Meter can be equipped with Laurel communication boards to support various interfaces and protocols. These include serial interfaces with ASCII or Modbus RTU protocols, and Ethernet interfaces with web access, ASCII, or Modbus TCP/IP protocols, ensuring versatile connectivity for your commercial applications.
What Is a 1/8 DIN Panel Meter for True RMS AC Voltage?
A 1/8 DIN Panel Meter for True RMS AC Voltage is a specialized electronic device used in various industrial and commercial applications to measure and display the true root mean square (RMS) value of an alternating current (AC) voltage. This type of Panel Meter is commonly utilized in situations where accurate measurement of AC voltage is crucial, such as in power systems, electrical equipment, and industrial automation.
1/8 DIN Form Factor
The term 1/8 DIN refers to the physical size and mounting style of the Panel Meter. DIN stands for Deutsches Institut für Normung, a German standards organization. DIN sizes are standardized dimensions that ensure compatibility with a variety of mounting systems and enclosures. A 1/8 DIN Panel Meter has a front panel size of 96mm x 48mm (3.78 inches x 1.89 inches), making it compact and suitable for use in control panels where space is limited.
True RMS Measurement
True RMS (Root Mean Square) measurement is a critical feature of this type of Panel Meter. In AC circuits, the voltage waveform can be sinusoidal (pure AC) or non-sinusoidal (with harmonics or distortions). A conventional average-responding Panel Meter can give inaccurate readings for non-sinusoidal waveforms because it assumes a pure sine wave. However, a True RMS Panel Meter accurately measures the equivalent DC value that would produce the same heating effect in a resistive load, regardless of the waveform's shape.
This accuracy is essential in modern electrical systems, where non-linear loads like variable frequency drives (VFDs), switching power supplies, and other electronic devices generate distorted waveforms. A 1/8 DIN Panel Meter with True RMS capability ensures precise voltage measurement under these conditions, making it invaluable in today's complex electrical environments.
Key Features and Benefits
- Compact Size: The 1/8 DIN form factor allows easy integration into crowded control panels, optimizing space without compromising on functionality.
- High Accuracy: True RMS measurement ensures accurate voltage readings even with distorted or non-sinusoidal waveforms, which is critical for reliable monitoring and control.
- Digital Display: This Panel Meter features a clear, easy-to-read digital display, typically with adjustable brightness for visibility in various lighting conditions.
- Versatility: Suitable for a wide range of applications, including monitoring power supplies, generators, motor drives, and other AC-powered equipment.
- Ease of Installation: Designed for easy panel mounting, this Panel Meter often comes with user-friendly interfaces and standard connections, simplifying installation and setup.
- Wide Input Range: Modern 1/8 DIN Panel Meter models offer wide AC voltage input ranges, typically from 0-600VAC or higher, accommodating various electrical systems without requiring external scaling devices.
- Fast Response Time: The Panel Meter provides rapid measurement updates, typically 2-10 readings per second, enabling real-time monitoring of voltage fluctuations and transients.
- Alarm Outputs: Many 1/8 DIN Panel Meter models include programmable alarm outputs that activate when voltage exceeds or falls below user-defined thresholds, providing early warning of potential problems.
Technical Specifications
A typical 1/8 DIN Panel Meter for True RMS AC Voltage includes several advanced specifications:
- Measurement Accuracy: Typically ±0.5% to ±1.0% of reading, ensuring reliable voltage monitoring.
- Frequency Range: Capable of measuring AC voltage across a wide frequency range, typically 45-65Hz for standard power applications, with some models extending to 1kHz or higher for specialized applications.
- Crest Factor: Handles crest factors of 3:1 or higher, allowing accurate measurement of highly distorted waveforms.
- Input Impedance: High input impedance (typically >1MΩ) minimizes circuit loading and ensures accurate measurements.
- Isolation: Input-to-output electrical isolation (typically 2kV or higher) for safety and to prevent ground loops.
- Display Resolution: 4 to 6-digit LED or LCD displays with configurable decimal points for optimal readability.
- Power Supply: Available in AC (85-265VAC) or DC (12-48VDC) versions with universal power input options.
Applications
A 1/8 DIN Panel Meter for True RMS AC Voltage is widely used in industries where precise voltage monitoring is crucial. Common applications include:
- Power Distribution: Monitoring voltage levels in power distribution panels to ensure consistent and safe operation of electrical systems.
- Industrial Automation: Used in control panels to monitor voltage in various processes, ensuring equipment operates within safe voltage ranges.
- HVAC Systems: Measuring and displaying voltage in heating, ventilation, and air conditioning systems to maintain optimal performance.
- Laboratory Testing: Employed in test benches and laboratories for accurate voltage measurement in research and development projects.
- UPS Systems: Monitoring output voltage from uninterruptible power supplies to ensure clean, stable power delivery to critical loads.
- Generator Monitoring: Displaying generator output voltage to verify proper operation and load management.
- Motor Control Centers: Monitoring supply voltage to motor control equipment to prevent damage from over-voltage or under-voltage conditions.
Advantages Over Standard AC Voltage Measurement
The True RMS capability of this Panel Meter provides significant advantages:
- Harmonic Immunity: Accurately measures voltage in the presence of harmonics generated by electronic loads.
- Waveform Independence: Provides correct readings regardless of waveform shape, including square waves, triangle waves, and complex distorted waveforms.
- Power Quality Monitoring: Enables detection of power quality issues that could affect sensitive electronic equipment.
- Compliance: Meets requirements for accurate voltage measurement in applications subject to electrical codes and standards.
Where Is a 1/8 DIN Panel Meter for True RMS AC Voltage Used?
A 1/8 DIN Panel Meter is a crucial tool in various industries for monitoring and displaying electrical parameters like voltage, current, and frequency. When this Panel Meter is designed specifically for True RMS (Root Mean Square) AC voltage measurement, it becomes even more vital in environments where accuracy is paramount.
1. Industrial Automation and Control Systems
In industrial environments, ensuring the correct functioning of machinery and processes is critical. A 1/8 DIN Panel Meter is often integrated into control panels to monitor the AC voltage supplied to equipment. True RMS measurement is essential in these settings because industrial equipment can draw non-linear loads, leading to distorted waveforms.
2. Power Distribution and Monitoring
Power distribution systems, especially those dealing with complex loads, require precise voltage monitoring to ensure stability and efficiency. A 1/8 DIN Panel Meter with True RMS capability is used in switchgear, transformers, and distribution panels to monitor voltage levels and detect any anomalies that could lead to power quality issues or equipment failure.
3. Renewable Energy Systems
Renewable energy systems, such as solar power inverters and wind turbines, often produce non-sinusoidal waveforms due to the nature of the conversion process from DC to AC. Using a 1/8 DIN Panel Meter that measures True RMS AC voltage ensures accurate monitoring of the voltage output.
4. HVAC Systems
Heating, ventilation, and air conditioning (HVAC) systems rely on precise voltage control for efficient operation. A True RMS Panel Meter is used to monitor the AC voltage supplied to motors and compressors within these systems.
5. Laboratory and Testing Environments
In laboratory settings, where experiments and equipment testing often require exact voltage measurements, a 1/8 DIN Panel Meter with True RMS capabilities is indispensable.
6. Data Centers and IT Infrastructure
Data centers and IT infrastructure require a stable power supply to avoid disruptions. A 1/8 DIN Panel Meter with True RMS AC voltage measurement is used to monitor power supply lines.
7. Manufacturing Facilities
In manufacturing plants, the Panel Meter monitors voltage supplied to production machinery, welding equipment, and automated assembly lines. True RMS measurement is critical in environments with heavy inductive loads, such as motors and transformers.
8. Commercial Buildings
Building management systems in commercial facilities use the Panel Meter to monitor electrical distribution throughout the building, including voltage to elevators, lighting systems, and HVAC equipment.
9. Marine and Offshore Applications
Ships, oil platforms, and offshore installations rely on the Panel Meter to monitor AC power systems in harsh environmental conditions.
10. Entertainment and Broadcast
In broadcast studios, concert venues, and entertainment facilities, the Panel Meter monitors voltage supplied to audio equipment, lighting systems, and video production gear.
Industry-Specific Benefits
- Reduced Maintenance Costs: Early detection of voltage anomalies through accurate True RMS measurement helps prevent equipment damage and reduces maintenance expenses.
- Energy Efficiency: The Panel Meter helps identify voltage inefficiencies, enabling optimization of power consumption across facilities.
- Compliance and Safety: Accurate voltage monitoring helps facilities meet electrical safety codes and regulatory requirements.
- System Reliability: Continuous monitoring with the Panel Meter ensures stable operation of critical systems, reducing unexpected downtime.
Conclusion
A 1/8 DIN Panel Meter for True RMS AC voltage measurement is a versatile instrument used across various industries. Its ability to provide accurate voltage readings, even with distorted waveforms, makes it indispensable in industrial automation, power distribution, renewable energy, HVAC systems, laboratories, and data centers.
True RMS AC Voltage Panel Meter Frequently Asked Questions
What exactly is crest factor, and what does a meter's crest factor rating mean in practice?
Crest factor is the ratio of a waveform's peak value to its RMS value — 1.414 for a perfect sine wave, and higher for more distorted or "peaky" waveforms. A meter's crest factor specification defines the maximum peaking it can measure without introducing error, so a signal with a crest factor beyond the meter's rating will produce an inaccurate reading even though the meter is a genuine True RMS design.
Does a higher crest factor rating always mean better accuracy on distorted waveforms?
Generally yes, but bandwidth matters just as much — a meter can have an excellent crest factor rating and still misread a distorted waveform if its bandwidth is too narrow to capture the higher-frequency harmonic content that makes up that distortion. Both specifications need to be adequate for the waveform being measured, not just one or the other.
What input impedance should this Panel Meter have, and why does it matter?
High input impedance (typically above 1 MΩ) minimizes the amount of current the meter itself draws from the circuit being measured, which prevents the meter from "loading down" and slightly altering the voltage in high-impedance or sensitive circuits. This matters less on low-impedance power circuits but can matter significantly in more sensitive measurement applications.
What frequency range does this Panel Meter's True RMS measurement actually cover?
Standard models are typically rated for the 45-65Hz range covering standard 50/60Hz power, with some models extending to 1kHz or beyond for applications involving VFD outputs or other higher-frequency distorted waveforms. The meter's rated frequency range should be checked against the actual frequency content of the signal being measured, not just the fundamental line frequency.
Why does this Panel Meter need input-to-output isolation, and how much is typically provided?
Isolation, commonly rated at 2kV or higher between input and output, protects both the measurement circuit and any connected equipment from transients and prevents ground loops that could otherwise introduce measurement error or safety hazards, particularly important given the voltage levels typically involved in AC power monitoring.
Can this meter be used to detect power quality problems beyond just voltage level?
Yes, True RMS measurement is a foundational tool for power quality monitoring, since it can reveal the presence of harmonic distortion affecting the voltage that a simple average-responding meter would mask, even though a dedicated power quality analyzer with additional harmonic-analysis capability is typically needed for detailed diagnosis beyond just detecting that distortion exists.
How fast does this Panel Meter update its reading, and does that matter for catching voltage transients?
Update rates commonly range from 2 to 10 readings per second on standard models, which is adequate for monitoring general voltage trends but not fast enough to capture very brief transients — applications specifically needing to catch fast transient events typically require dedicated transient-capture instrumentation rather than a standard panel meter's update rate.
What accuracy class should I expect from a True RMS AC voltage Panel Meter?
Typical accuracy specifications fall in the ±0.5% to ±1.0% of reading range, though this accuracy is generally specified under standard sine-wave conditions and can be affected on more distorted waveforms depending on how close the signal's crest factor and harmonic content are to the meter's rated limits.
Can this meter accept AC voltage inputs across a very wide range, like both 120V and 480V systems, without external equipment?
Many models offer a wide input range (commonly up to 600VAC or higher) covering common industrial voltage levels directly, without requiring an external potential transformer, though voltages beyond the meter's rated maximum still require external scaling regardless of how wide the built-in range is.
Does this Panel Meter's alarm output respond to instantaneous voltage or an averaged/filtered value?
This depends on the specific model's configuration, and it matters for how the alarm behaves on a fluctuating signal — an alarm based on unfiltered instantaneous readings will trigger more readily on brief spikes, while a filtered or averaged basis produces a steadier alarm behavior at the cost of slower response to genuine changes.
True RMS AC Voltage Panel Meter Questions From the Field
Why do two True RMS meters, both from reputable brands, give noticeably different readings on the exact same distorted signal?
This has been extensively documented in electrical forums, and the root cause is almost always differing crest factor and bandwidth specifications between the two meters rather than either meter being "wrong" — one meter's true RMS conversion circuitry may saturate or lose accuracy at a lower crest factor than the other, or one may simply have narrower bandwidth and miss higher-frequency harmonic content the other captures. Comparing both meters' full specifications, not just whether each is labeled "true RMS," explains the discrepancy.
Can a meter labeled "True RMS" still give an incorrect reading on certain waveforms?
Yes — this has been documented as a real, sometimes surprising finding: a meter labeled true RMS by its manufacturer isn't necessarily performing a genuine numerical RMS calculation across all conditions, and can be "true RMS only under certain conditions" according to its own internal design assumptions. Comparing a questionable reading against a bench-grade instrument or an oscilloscope's calculated RMS value is the recommended way to verify a field meter's reading when the result seems suspicious.
My true RMS meter's reading seems to drop off at frequencies above or below standard line frequency — is that expected?
This has been reported and explained in field discussions: above standard line frequency, response can drop due to the frequency response limits of the current transformer or the meter's internal rectifier circuitry, while at frequencies well below the standard, core saturation in a current transformer (due to its low inductance at low frequency) can similarly cause the reading to fall off. Both effects are separate from — and in addition to — any crest factor or bandwidth limitation related to waveform distortion.
If I filter out the high-frequency harmonics from a distorted signal, will two different meters then agree with each other?
This has been directly demonstrated in a documented field test — two meters that disagreed significantly on an unfiltered, harmonic-rich signal came into close agreement once the signal was passed through a low-pass filter removing content above roughly 95 Hz, confirming that the original disagreement was caused by harmonic content interacting differently with each meter's internal circuitry, not a calibration problem with either instrument.
Does a "flat-topped" sine wave, which is common on real-world industrial power, actually affect True RMS meter accuracy?
This has been discussed at length in electrical forums, and the practical conclusion is that a mildly flat-topped waveform (common due to how modern electronic loads draw current from the grid) generally produces little to no significant measurement difference between a true RMS meter and other reference instruments, since the crest factor of a flat-topped sine wave is actually somewhat lower than an ideal sine wave's 1.414, keeping it well within most meters' accurate range.
Why does my True RMS meter give a stable, believable-looking reading that still turns out to be wrong when checked against a scope?
This is one of the more subtle documented issues — a meter can produce a perfectly stable, plausible-looking number that's still numerically incorrect if the signal's crest factor or harmonic content exceeds what that specific meter's internal circuitry can handle accurately, since the meter doesn't necessarily flag when it's operating outside its accurate range. Periodically cross-checking field meter readings against an oscilloscope's calculated RMS value, particularly on signals known to be distorted, is the recommended way to catch this.
Is there a rule of thumb for how much bandwidth a True RMS meter needs for typical industrial drive or harmonic-rich measurements?
Field and technical guidance generally suggests at least 1 kHz of bandwidth for reliable measurement of industrial VFD and drive-related waveforms, since the meaningful distortion content in these signals commonly extends well beyond standard 50/60 Hz line frequency into that range — a meter with only line-frequency bandwidth will produce the same kind of inaccurate reading on a distorted signal as a non-true-RMS meter would, regardless of its crest factor rating.
