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 Digital Panel Meters for True RMS
are 60,000 count digital panel meters 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 digital panel meters. 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 Digital 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.
Laureate Digital Panel Meters are 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™ Digital Panel Meters use a 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.
Modular 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 Digital Panel Meters.
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 Digital Panel Meters to a Local Area Network (LAN)
Up to 30 Laureate Digital Panel Meters 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 Digital Panel Meters
Laureate Digital Panel Meters 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.
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 | |
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|
| 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
$47.00What Are 1/8 DIN Digital Panel Meters for True RMS AC Voltage?
1/8 DIN Digital Panel Meters for True RMS AC Voltage are specialized electronic devices used in various industrial and commercial applications to measure and display the true root mean square (RMS) value of alternating current (AC) voltage. These types of Digital Panel Meters are 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 Digital Panel Meters. 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. 1/8 DIN Digital Panel Meters have a front panel size of 96mm x 48mm (3.78 inches x 1.89 inches), making them 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 these types of Digital Panel Meters. In AC circuits, the voltage waveform can be sinusoidal (pure AC) or non-sinusoidal (with harmonics or distortions). Conventional average-responding instruments can give inaccurate readings for non-sinusoidal waveforms because they assume a pure sine wave. However, True RMS Digital Panel Meters accurately measure 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. 1/8 DIN Digital Panel Meters with True RMS capability ensure precise voltage measurement under these conditions, making them 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: These Digital Panel Meters feature clear, easy-to-read digital displays, 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, these Digital Panel Meters often come with user-friendly interfaces and standard connections, simplifying installation and setup.
Applications
1/8 DIN Digital Panel Meters for True RMS AC Voltage are 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.
Where Are 1/8 DIN Digital Panel Meters for True RMS AC Voltage Used?
1/8 DIN Digital Panel Meters are crucial tools in various industries for monitoring and displaying electrical parameters like voltage, current, and frequency. When these Digital Panel Meters are designed specifically for True RMS AC voltage measurement, they become even more vital in environments where accuracy is paramount.
Understanding True RMS Measurement
True RMS is a method of measuring the effective value of an alternating current (AC) or voltage waveform. Unlike average or peak measurement methods, True RMS provides an accurate representation of the power that a waveform can deliver, regardless of its shape. This is particularly important for non-sinusoidal waveforms, where other measurement methods can lead to significant errors.
Key Applications of 1/8 DIN Digital Panel Meters for True RMS AC Voltage
- Industrial Automation and Control Systems
In industrial environments, ensuring the correct functioning of machinery and processes is critical. 1/8 DIN Digital Panel Meters are 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. Accurate voltage monitoring helps in maintaining the efficiency and longevity of machinery. - Power Distribution and Monitoring
Power distribution systems, especially those dealing with complex loads, require precise voltage monitoring to ensure stability and efficiency. 1/8 DIN Digital Panel Meters with True RMS capability are 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. - 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 1/8 DIN Digital Panel Meters that measure True RMS AC voltage ensures accurate monitoring of the voltage output, which is crucial for optimizing system performance and ensuring safe operation. - HVAC Systems
Heating, ventilation, and air conditioning (HVAC) systems rely on precise voltage control for efficient operation. True RMS Digital Panel Meters are used to monitor the AC voltage supplied to motors and compressors within these systems. Given the potential for voltage fluctuations and waveform distortion in HVAC applications, True RMS measurement is necessary to maintain system reliability. - Laboratory and Testing Environments
In laboratory settings, where experiments and equipment testing often require exact voltage measurements, 1/8 DIN Digital Panel Meters with True RMS capabilities are indispensable. These Digital Panel Meters ensure that the voltage supplied to sensitive instruments is accurate, reducing the risk of erroneous results or damage to equipment. - Data Centers and IT Infrastructure
Data centers and IT infrastructure require a stable power supply to avoid disruptions. 1/8 DIN Digital Panel Meters with True RMS AC voltage measurement are used to monitor power supply lines, ensuring that any deviation from the norm is quickly detected and addressed. This helps in preventing downtime and protecting critical IT equipment from voltage-related damage.
Conclusion
1/8 DIN Digital Panel Meters for True RMS AC voltage measurement are versatile instruments used across various industries. Their ability to provide accurate voltage readings, even with distorted waveforms, makes them indispensable in industrial automation, power distribution, renewable energy, HVAC systems, laboratories, and data centers. By ensuring precise monitoring and control of AC voltage, these Digital Panel Meters contribute significantly to the efficiency, safety, and reliability of electrical systems.
True RMS AC Voltage Digital Panel Meter Frequently Asked Questions
What does "true RMS" actually mean, in plain terms?
True RMS means the meter calculates the actual heating-equivalent value of a waveform — squaring the signal, averaging those squared values, then taking the square root — rather than assuming the waveform is a clean sine wave. This makes it accurate on distorted, non-sinusoidal signals, not just ideal AC.
Why would a true RMS meter and a standard average-responding meter show different readings on the same circuit?
An average-responding meter applies a fixed correction factor that's only valid for a pure sine wave. On distorted waveforms — common with VFDs, switch-mode power supplies, and other non-linear loads — that assumption breaks down, and the average-responding meter can read significantly high or low compared to the true RMS value, even though both meters are functioning correctly.
What is crest factor, and why does it matter for a True RMS meter?
Crest factor is the ratio between a waveform's peak value and its RMS value. A pure sine wave has a crest factor of about 1.41. Highly distorted or pulsed waveforms have a much higher crest factor, and a True RMS meter's specified crest factor rating indicates how distorted a signal it can still measure accurately — exceeding that rating can degrade accuracy even on a meter labeled True RMS.
Does a True RMS meter need a certain bandwidth to measure VFD or harmonic-rich signals accurately?
Yes. A True RMS meter's bandwidth determines how much of the harmonic content in a distorted waveform it can actually capture. A meter with too narrow a bandwidth can miss higher-frequency harmonic content and produce an inaccurate reading despite being a genuine True RMS design, so the meter's bandwidth spec should be checked against the frequency content of the waveform being measured.
Can this meter measure both AC and DC coupled signals?
Many True RMS panel meters offer jumper-selectable AC or DC coupling. AC coupling is useful for isolating the AC ripple component from a DC signal, such as measuring ripple on a DC power supply output, while DC coupling reads the full combined signal.
What is digital filtering used for on a True RMS meter, and when should I use it?
Digital filtering smooths out a reading in electrically noisy environments by averaging multiple conversions rather than displaying every instantaneous reading. An unfiltered setting shows true peak-to-valley response and is useful for control applications, while a filtered setting trades some response speed for a steadier displayed number — useful when the raw signal is jumping around due to noise rather than a genuine process change.
Can these meters be used with current transformers (CTs) instead of measuring voltage directly?
Yes. True RMS current models are commonly rated to accept the secondary output of standard current transformers directly, without needing a separate step-down transformer, and the meter reading can be scaled to account for the CT's turns ratio so it displays actual primary-side current.
What accuracy can I expect, and is it affected by the shape of the waveform being measured?
True RMS models in this class are typically factory-calibrated across multiple voltage or current ranges with the calibration data stored on the signal conditioner board. Accuracy is maintained across a range of waveform shapes precisely because the meter isn't relying on a sine-wave assumption, unlike an average-responding design.
Are relay, analog output, and communication options available on True RMS AC meters?
Yes. These meters commonly support optional relay outputs for alarms, an isolated analog retransmission output, and serial or Ethernet communications such as RS-485 or Modbus, allowing the True RMS reading to be used for alarming or fed into a PLC or SCADA system in addition to local display.
Is a True RMS meter necessary if my equipment only sees clean, sinusoidal power?
Not strictly — on a genuinely clean sine wave, a True RMS meter and a well-calibrated average-responding meter will read the same value. True RMS becomes necessary specifically when non-linear loads or distorted waveforms are present in the circuit being measured, which is increasingly common wherever VFDs, switching supplies, or electronic loads share a system.
True RMS AC Voltage Questions From the Field
Why do two meters on the same circuit give wildly different voltage readings?
This is a frequently reported field mystery, and it isn't always a True RMS vs. average-responding issue — in one documented case, technicians troubleshooting a faulting VFD compressor found several True RMS meters agreeing with each other while a non-RMS meter read differently, and the actual root cause turned out to be a difference in meter input impedance interacting with an ungrounded transformer secondary, not the RMS measurement method itself. The lesson generally drawn is to compare multiple meters of the same type before assuming a single "odd" reading is the fault.
Why does my meter read low when measuring the output of a UPS or inverter?
Average-responding meters are commonly reported to read noticeably low — sometimes 20-30% below actual — when measuring a stepped or approximated sine wave output, such as from a UPS running on battery or certain inverters. Switching to a genuine True RMS-rated meter is the standard fix, since the average-responding design's sine-wave correction factor doesn't apply to a stepped waveform.
Do I need a True RMS meter to measure frequency on a generator or VFD output?
Field discussion on this generally concludes no — True RMS affects the accuracy of voltage and current magnitude readings on distorted waveforms, but has no bearing on frequency counting, since frequency measurement is based on counting zero crossings or pulses rather than calculating an RMS value.
Can even a True RMS meter give a misleading reading on an inverter or VFD output?
Yes — this is a commonly raised caveat in field discussions: a True RMS meter sampling a fast-switching PWM waveform may not capture the true intermediate voltage levels within each switching cycle, since the signal at any given instant is essentially at a peak or near zero rather than smoothly varying, which can cause even a properly functioning True RMS meter to read high on certain modulated waveforms.
Why does my non-True-RMS clamp meter disagree with my drive's own displayed current reading?
This is a commonly reported mismatch, and the practical guidance from experienced technicians is not to rely on a VFD's own front-panel current display for precise readings, since drives typically report an averaged or estimated current value rather than a true RMS calculation — an external True RMS clamp meter is generally considered the more trustworthy reference when troubleshooting phase balance or current draw.
