RTD simulator comes with built-in climate control

Vishay Precision Group Inc. released a Bulk Metal Foil RTD Simulator resistor with built-in climate control from its Vishay Foil Resistors (VFR) brand.

Designed to simulate resistance temperature detector (RTD) PT-100 and PT-1000 outputs for the calibration of RTD instruments, the device features a low nominal TCR of ±1 ppm/°C from -55°C to 125°C, 25°C ref., and load-life stability of ±0.005 per cent after 2,000 hours of rated power at 70°C.

The device provides a faster, easier, and far less expensive alternative to decade boxes and electronic simulators for the calibration of transmitters, controllers, data acquisition, process control, and lab equipment in the field, shop, or control room. Each resistor comes with certification and features its specified temperature simulation—anywhere from -200°C to 850°C—clearly printed on the device for easy identification.

"The climate control capabilities of the RTD Simulator are provided by the inherently low absolute TCR of Bulk Metal Foil resistors, which itself results from two predictable and opposing physical phenomena within the composite structure of the resistive alloy and its substrate," said Yuval Hernik, senior director of application engineering for the VFR team. "The first is that the resistance of the alloy increases with the temperature. The second is that the coefficient of thermal expansion of the alloy and substrate are different, resulting in a compressive force on the alloy when the temperature increases and a consequent decrease of the foil resistance. The two effects occur simultaneously, resulting in an unusually low predictable, repeatable, and controllable TCR."

The RTD Simulator offers power ratings to 0.6W at 70°C and a maximum working voltage of 300V. The device features a resistance range from 10Ω to 5kΩ, with tight resistance tolerance to ±0.005 per cent (50ppm). Any conceivable ohmic value within this range, to six digits, is available with no additional cost or lead time effect.

Featuring a non-inductive (<0.08μH), non-capacitive design, the RTD Simulator offers a rise time of 1ns with effectively no ringing, thermal EMF of 0.05μV/°C, voltage coefficient of <0.1ppm/V, and current noise of 0.010μVRMS/V of applied voltage (<-40dB). The resistor withstands ESD spikes to at least 25kV and is available with both lead (Pb)-free and tin/lead alloy terminal finishes.

Samples and production quantities of the RTD Simulator are available now, with lead times of five working days for prototype samples and six weeks for standard orders.