Digital Panel Meter for True RMS AC Voltage & Current Applications
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.

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.
Sample Applications for True RMS AC Voltage and Current Applications Using the 1/8 DIN Digital Panel Meter
Introduction
In industrial automation, power management, and testing environments, accurate measurement of True RMS AC voltage and current is critical for ensuring system efficiency and reliability. Digital Panel Meters, such as the 1/8 DIN Digital Panel Meter for True RMS AC Voltage and Current from Laurel Electronics’ Laureate series, are designed to provide precise measurements of AC signals, accounting for non-sinusoidal waveforms. Featuring a 5-digit LED display, ±0.15% accuracy, and robust connectivity, this Digital Panel Meter is ideal for monitoring electrical parameters. This section explores where and how Digital Panel Meters are used in True RMS AC voltage and current applications, along with specific use cases, highlighting their essential role in industrial and commercial settings.
Understanding DIN Standards
The term "DIN" refers to the Deutsches Institut für Normung, the German Institute for Standardization, which establishes global standards for industrial components. The "1/8 DIN" designation indicates a compact size, with the Digital Panel Meter’s front panel measuring approximately 48 x 96 mm (1.89 x 3.78 inches). This space-efficient design makes Digital Panel Meters ideal for integration into control panels, particularly in environments with limited space.
What is a 1/8 DIN Digital Panel Meter for True RMS AC Voltage and Current Applications?
The 1/8 DIN Digital Panel Meter for True RMS AC Voltage and Current is a high-precision device optimized for measuring the true root mean square (RMS) value of AC voltage and current signals, including complex, non-sinusoidal waveforms. It supports input ranges from 200 mV to 600 V for voltage and 2 mA to 5 A for current, with a frequency range of 10 Hz to 10 kHz. Equipped with features like programmable scaling, setpoint control, and serial communication (RS-232, RS-485, Modbus), this Digital Panel Meter is a key tool for accurate electrical monitoring in industrial automation.
How Is It Used?
Digital Panel Meters process AC voltage and current signals to deliver accurate True RMS measurements, integrating seamlessly into control systems. The operational process includes:
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Signal Acquisition: Captures AC voltage (200 mV to 600 V) or current (2 mA to 5 A) signals from external sources like transformers or current sensors, with jumper-selectable ranges.
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Signal Processing: Employs True RMS conversion with a high-speed analog-to-digital converter (ADC) at up to 60 conversions per second, ensuring accurate measurements for non-sinusoidal waveforms, with ±0.15% accuracy.
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Display: Presents measurements on a 5-digit LED display, scalable to engineering units (e.g., V, A) from -99,999 to +99,999, with customizable scaling for specific applications.
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Output and Control: Provides dual 8A relays for setpoint control (e.g., overcurrent alarms), a 4-20 mA or 0-10 V analog output, and serial communication (RS-232, RS-485, Modbus) for integration with PLCs or SCADA systems.
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Signal Conditioning: Supports digital filtering to reduce noise and ensure stable readings, with a crest factor of 3.0 at full scale for handling complex waveforms.
Where Is a 1/8 DIN Digital Panel Meter for True RMS AC Voltage and Current Applications Used?
Digital Panel Meters are utilized in environments requiring precise measurement of AC voltage and current, particularly where non-sinusoidal waveforms are present, spanning industrial, commercial, and testing settings. Their compact size and high accuracy make them ideal for:
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Industrial Power Monitoring: Used in manufacturing plants to monitor electrical systems, ensuring efficient operation with Digital Panel Meters.
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Energy Management: Employed in commercial buildings to track power consumption, supported by Digital Panel Meters’ reliable performance.
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Electrical Testing Laboratories: Used for precise measurement of AC signals in research and development, with Digital Panel Meters’ high-resolution displays.
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HVAC Systems: Monitors electrical parameters in heating, ventilation, and air conditioning systems, with Digital Panel Meters enhancing accuracy.
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Power Distribution: Tracks voltage and current in utility systems to ensure grid stability, supported by Digital Panel Meters’ robust capabilities.
Applications for True RMS AC Voltage and Current Use Cases
- Industrial Automation
- Motor Monitoring: Digital Panel Meters measure True RMS current in motors to ensure efficient operation and detect overcurrent conditions, preventing equipment damage.
- Equipment Control: Digital Panel Meters monitor voltage in automated machinery, triggering alarms or control actions for system stability.
- Energy Management
- Power Consumption Tracking: Digital Panel Meters monitor True RMS voltage and current in commercial buildings to optimize energy usage and reduce costs.
- Load Balancing: Digital Panel Meters measure current across phases to ensure balanced power distribution, enhancing system efficiency.
- Electrical Testing and Research
- Signal Analysis: Digital Panel Meters measure True RMS values of complex AC waveforms in testing labs, ensuring accurate data for equipment development.
- Device Calibration: Digital Panel Meters verify voltage and current in calibration setups, supporting precise instrument performance.
- HVAC Systems
- Compressor Monitoring: Digital Panel Meters track current in HVAC compressors to ensure efficient operation and prevent overloads.
- Power Quality Control: Digital Panel Meters measure voltage fluctuations to maintain stable power supply in HVAC systems.
- Power Distribution
- Grid Monitoring: Digital Panel Meters measure True RMS voltage and current in substations to ensure grid stability and reliability.
- Fault Detection: Digital Panel Meters detect abnormal current levels in power distribution systems, triggering alarms for maintenance.
Why Choose a 1/8 DIN Digital Panel Meter for True RMS AC Voltage and Current Applications?
Digital Panel Meters, such as the Laureate 1/8 DIN model, offer exceptional precision, robust connectivity, and a compact design, making them ideal for True RMS AC voltage and current applications. Their ability to accurately measure non-sinusoidal waveforms, support setpoint control, and provide serial communication ensures reliable performance. Digital Panel Meters integrate seamlessly into modern automation and monitoring systems, enhancing efficiency, safety, and control.
Conclusion
The 1/8 DIN Digital Panel Meter for True RMS AC Voltage and Current Applications is a powerful and versatile tool for industrial automation, energy management, electrical testing, HVAC systems, and power distribution. Its high-precision 5-digit display, ±0.15% accuracy, and advanced features like True RMS conversion and Modbus connectivity ensure reliable measurement of AC signals. Operating from -40°C to 70°C with CE/RoHS3 compliance, Digital Panel Meters are a cornerstone of modern electrical monitoring systems, supporting accuracy and efficiency across diverse industries.
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