L-RM, Laurel Laureate True RMS AC Voltage & Current Meter, 1 Cycle Update at 50/60 Hz.
- 0.2, 2, 20, 200 & 600V AC or AC+DC voltage ranges
- 2, 20, 200 mA & 5A AC or AC+DC current ranges
- True AC RMS measurement with crest factor of 3.0 at full scale
- Fast response: reading in 0-16.7 ms after each signal cycle to full accuracy
- Accurate to 0.03% of full scale, 0.1% to 100% of FS, 10 Hz to 15 kHz
- Universal 85-264 Vac / 90-300 Vdc or 10-48 Vdc / 12-32 Vac power
- Wide choice of options:
- - 2 or 4 relays, mechanical or solid state (isolated)
- - Analog output, 4-20 mA, 0-10V, or -10V to +10V (isolated)
- - Serial data I/O: Ethernet, USB, RS485, RS232 (isolated)
- - Custom curve linearization, rate from consecutive readings
The Laureate™ True RMS meter is a 60,000 count digital panel meter with exceptional performance at half the price of a bench top meter. It can measure true RMS voltage 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 to 0.1% of full scale for signals from DC to 10 kHz and signal amplitudes down to 0.1% of full scale. 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 on the signal conditioner board. AC coupling accommodates signals from 10 Hz to 10 kHz and is suitable for applications such as measuring AC ripple on a DC power supply. DC coupling accommodates signals from 0 to 10 kHz. 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 3/sec.
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.
Designed for system use. Optional plug-in boards for communications and control include Ethernet and other serial communication boards, dual or quad relay boards, and an isolated 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 red or green LEDs. 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. All power and signal connections are via UL / VDE / CSA rated screw clamp plugs.
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.
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)
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.
L-RM, True RMS meter Datasheet |
L-RM, True RMS meter Manual |