LT DIN Rail Analog Transmitter with Serial Data Communication and Analog Outputs for True RMS AC Voltage and Current Applications

The Laureate 4-20 mA, 0-20 mA, 0-10V or -10V to +10V and RS232/RS485 output transmitter for true RMS AC voltage or current input offers the same high performance, signal conditioning, and programmable features as Laureate digital panel meters, counters, and timers. It provides six voltage input ranges and four current input ranges, all factory calibrated and jumper selectable. A special 5.000A range utilizes a built-in 0.01 ohm shunt to accept the output of 5A current transformers, eliminating the need for a step-down transformer. The voltage readings can be scaled digitally as needed. High common mode rejection allows for stable readings with current shunts located on the high side of the line. Digital filtering is selectable for noisy signals.

• 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 two solid state relays. The transmitter can also capture peak and valley readings that occur at the nominal rate of 50/60 Hz.
• Accuracy is 0.03%  of full scale for the transmitters with 1 Megohm input resistance, signals from DC to 5 kHz, and signal amplitude down to 0.5. The crest factor (Vp / Vrms) is 3.0 at full scale, increasing to 300 for a signal amplitude of 1% 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.
• 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 transmitter, with no need for a stepdown transformer. The transmitter 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 transmitter. 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 transmitter 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 transmitter for precise operation.

Laureate Transmitters 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™ LT Series transmitter uses 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.

Standard Hardware Features of Laureate LT Transmitters Include:

• Serial communications output, (isolated), RS232 or RS485 (half or full duplex), jumper selectable. Three protocols are user selectable: Modbus RTU, Modbus ASCII, or Laurel ASCII. Modbus operation is fully compliant with Modbus Over Serial Line Specification V1.0 (2002). The Laurel ASCII protocol is simpler than the Modbus protocol and is recommended when all devices are Laureates.
• 4-20 mA, 0-10V or -10V to +10V analog transmitter output, (isolated), jumper-selectable and user scalable. All selections provide 0.0015% resolution of output span and 0.02%  output accuracy of a reading from -99,999 to +99,999 counts that is also transmitted digitally. Output isolation from signal and power grounds eliminates potential ground loop problems. Note that Ethernet data I/O is provided by Laurel's LTE series transmitters.
• Dual solid state relays, (isolated), for alarm or control. Rated 120 mA at 130 Vac or 180 Vdc.
• Selectable transducer excitation output, (isolated), user selectable 5V@100 mA, 10V@120 mA, 12V@100mA, or 24V@50 mA.
• Power 85-264 Vac, (isolated), low-voltage 10-48 Vdc or 12-32 Vac power is optional.

• 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. This causes the current weight, which is normally the empty weight of the container to be stored in memory as an offset. In manual tare, the tare value can be entered manually via a control input pushbutton or using Laurel's free Instrument Setup Software.

Peak and valley values are automatically captured. These may be displayed via Laurel's free Instrument Setup Software,  which runs on a PC under MS Windows or can be transmitted as serial data.

Two 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 transmitter commands.