Laureate™ Pt100, Ni120, Cu10 RTD Meter & Controller

High meter accuracy plus linearized transmitter & control outputs
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RTD temperature meter by Laurel Electronics
Key Features
  • Accepts Pt100, Ni120 & Cu10 RTD temperature sensors
  • 2, 3 or 4-wire connection with lead resistance compensation
  • Highly accurate and repeatable
  • Selectable 1°, 0.1°, or 0.01° resolution
  • Selectable Celsius, Fahrenheit, Kelvin or Rankin scales
  • Up to 60 conversions per second
  • Peak or valley display
  • Universal AC power, 85-264 Vac
  • NEMA 4X, 1/8 DIN case
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 outputs: isolated 4-20 mA, 0-20 mA, 0-10V, 10 to +10V
Description

The Laureate™ RTD meter is factory calibrated for four Resistance Temperature Detector (RTD) types: 100 ohm platinum (Pt100) with DIN alpha of 0.00385, 100 ohm platinum (Pt 100) with ANSI alpha of 0.003902, 10 ohm copper with alpha of 0.00427, and 120 ohm nickel with alpha of 0.00672. The entire span of each RTD type is presented in a single range. The RTD type, unit of measure (°C or °F) and resolution (1°, 0.1° or 0.01°) are selectable from the front panel or via the meter's serial interface. Display in Kelvin or Rankin is selected by offsetting the Celsius or Fahrenheit ranges.

RTD connections can be via 2, 3 or 4 wires. With 3 or 4-wire connections, the meter automatically compensates for lead resistance to the sensor. With 2-wire connection, the meter can measure and then subtract the lead wire resistance.

All ranges for all RTD types are digitally calibrated at the factory, with calibration factors stored in an EEPROM on the signal conditioner board. This allows temperatures sensors and signal conditioner boards to be changed in the field without recalibrating the meter.

Load cell signal conditioner board for Laurel digital panel meter High read rates at up to 60 or 50 conversions per second while integrating the signal over a full power cycle are provided by Concurrent Slope (US Pat 5,262,780) analog-to-digital conversion. High read rates are ideal for peak or valley capture, real-time computer interface, and control. Peak and valley values are standard. These may be displayed via a front panel pushbutton command or a control signal at the rear connector, or be transmitted as serial data.

Digital filtering is selectable for electrically noisy environments or resolution to 0.01°, including a batch averaging filter and an adaptive moving average filter which provides a choice of 8 time constants from 80 ms to 9.6 s. When a significant change in signal level occurs, that filter adapts by briefly switching to the shortest time to follow the change, then reverts back to the selected time constant. In a selectable Auto filter mode, the filter time constant is automatically selected based on detected signal noise.

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 anisolated 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.

RTD Connections with Excitation & Lead Compensation

RTD hookup can be via 2, 3 or 4 wires to the J5 connector. The meter applies an excitation current of 196 µA (Pt100 and Ni120) or 5 mA (Cu10).

In 4-wire hookup, different pairs of leads are used to apply the excitation current and sense the voltage drop across the RTD, so that the IR drop across the excitation leads is not a factor.

In 3-wire hookup, the meter senses the combined voltage drop across the RTD plus two excitation leads. It also senses the voltage drop across one excitation lead, and then subtracts twice this voltage from the combined total. This technique effectively subtracts all lead resistance and compensates for ambient temperature changes if the two excitation leads are identical.

In 2-wire hookup, the meter senses the combined voltage drop across the RTD and both lead wires. The voltage drop across the lead wires can be measured by shorting out the RTD during meter setup, and this voltage is then automatically subtracted from the combined total. However, changing resistance of the lead wires due to ambient temperature changes will not be compensated.

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