The True RMS AC digital panel meters use precision circuitry to compute the root-mean-square of complex waveforms from 10 Hz to 10 kHz. Spikes up to 2.4 times the maximum of each range are accurately measured. This provides a crest factor (Vp / Vrms) of 240 for a signal amplitude of 1% of full scale, decreasing to 2.4 at 100% of full scale.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 5 A current transformers to be applied directly to the meter, with no need for a stepdown transformer. The current reading can easily be scaled to display the input to the current transformer. Digital scaling and calibration eliminate zero and span drift associated with potentiometers in non-microcomputer based meters.
Crest factor increases in inverse proportion to signal amplitude. As shown on the same graph, the maximum crest factor (Vp / Vrms) is 2.4x at full-scale amplitude, increasing to 240 at 1% of full-scale amplitude.The Laureate True RMS AC ammeter utilizes the same high-speed analog-to-digital conversion method as all other Laureate digital panel meters. However, the meter settling time and control response to a step change in AC amplitude are limited by the True RMS AC converter circuit to approximately 1 second.
|AC Voltage (1% to 100% of full scale)||AC Voltage Range||Resolution||Input Ohms||Typ Error at 25°C|
10 Hz to 10 kHz
|2.000 V||100 µV
|200.00 V||10 mV
|660.0 V||100 mV||1 M|
|AC Current (1% to 100% of full scale)||AC Voltage Range||Resolution||Input Ohms||Typ Error at 25°C|
|2.0000 mA||0.1 µA||100
10 Hz to 10 kHz
|20.000 mA||1.0 µA
|5.000 A||1.0 mA||0.01|
|Span Tempco||0.0015% of reading/°C
|660 Vac for 20, 200 and 600 V ranges, 125 Vac for other
|Zero Tempco||0.1 µV/°C||Overcurrent
|25x for 2 mA, 8x for 20 mA, 2.5x for 200 mA, 1x for 5 A|
|Crest Factor||2.4x at 100% of full scale||-----||-----|
|RMS to DC||1 s conversion settling time||Readout||5 digits, 7-segment, 14.2 mm (.56")|
|A-to-D Rate||60/s at 60 Hz, 50/s at 50 Hz||Color||Red or green LED|
|Output Update||56/s at 60 Hz, 47/s at 50 Hz||Range||-99999 to +99999 or -99990 to +99990 (count by 10 with
|Display Update||3.5/s at 60 Hz, 3/s at 50 Hz||Indicators||2 red LED lamps|
|Voltage, std||85-264 Vac and 90-370 Vdc||5 Vdc||5 Vdc ±5%, 100 mA max|
|Voltage, opt||8-28 Vac and 9-37 Vdc||10 Vdc||10 Vdc ±5%, 120 mA max|
|Frequency||DC or 49-440 Hz||24 Vdc||24 Vdc ±5%, 50 mA max|
|Power isolation||Safety-rated to 250 Vac, meter ground to earth ground,
DC to 60 Hz, 4.2 kVp per High Voltage Test
|Output isolation||50 Vdc to meter ground|
|Operating Temperature||0°C to 55°C|
|Storage Temperature||-40°C to 85°C|
|Relative HumidityProtection||NEMA-4X (IP-65) when panel mounted|
Laureate meters and counters are low-cost means to instrument AC power lines with great accuracy:AC RMS Voltmeter. Full-scale ranges of interest are 200.00 V with 10 mV resolution and 660.0 V with 100 mV resolution. True RMS capability allows the display of RMS voltage for non-sinusoidal waveshapes, such as square waves from a UPS.
AC RMS Ammeter. A built-in 5 A range can be used to display currents up to 5.000 A with 10 mA resolution, or to 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 to 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 Meter. Two signals with identical periods are applied to Channels A and B of the Laureate phase angle meter. A display from -180º to +180º is obtained by timing the rising edge of one channel and the falling edge of the other channel. A resolution of 1º, 0.1º or 0.01º is selectable. Accuracy is .01% up to 100 Hz, .1% at 1 kHz, and 1% at 10 kHz.
The two voltages can be measured by two Laureate AC RMS Voltmeters, which offer 200.00 V and 660.0 V ranges. Or a single meter can be multiplexed by using an external toggle switch.The two frequencies 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.
Phase angle can be measured using the Laureate Dual Channel Counter.