Laurel True RMS Digital Panel Meter & Controller

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 is 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. UL 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.

Standard Features

0.2, 2, 20, 200 & 600V voltage ranges with 132% overrange
2, 20, 200 mA & 5A current ranges with 132% overrange
All ranges factory calibrated
Display flashes at 132% overrange
Scalable to 5 digits for external current shunts or 5A current transformers
Selectable peak or valley display
85-264 Vac universal AC power
Green or red display
NEMA 4X, 1/8 DIN case
Priced competitively with less capable AC meters

Options

Serial communications: Ethernet Interface, Ethernet-to-RS485 server, USB Interface, USB-to-RS485 server, RS485 interface (dual RF11), RS485 Modbus interface (dual RJ45), RS232 interface.
Low voltage power: 10-48 Vdc or 12-32 Vac
Relay outputs: 2 or 4 relays, contact or solid state
Analog output: Isolated 4-20 mA, 0-20 mA, 0-10V, -10 to +10V