PT1000 RTD
A Pt1000 follows the same IEC 60751 Callendar–Van Dusen curve as Pt100 but scaled by 10× — 1 000 Ω at 0 °C, 1 385.1 Ω at 100 °C. Shipped in the same physical packages (TO-92, screw-in probes, ring-lug rings) and tolerance classes (A, B). Examples: Heraeus W-EYK 1PT1000-RA, Innovative Sensor Technology P1K0.232.6W.B.007.
The element is the same platinum thin film as a Pt100 with ten times the printed length and slimmer pattern, on the same alumina substrate. A 2-wire Pt1000 measurement biases the sensor at typically 250 µA and reads its terminal voltage; copper lead resistance of ~ 1 Ω adds 0.25 °C error rather than 2.5 °C as it would on a Pt100, often acceptable without the cost of 3-wire/4-wire wiring.
In plain terms
A Pt100 'thread' wrapped ten times longer: the same calibration curve, but bigger absolute Ω numbers so a few extra ohms of cable resistance are an unnoticed rounding error rather than a serious bias.
Why designers use it
- Provide accurate HVAC supply/return-air temperature on long thermostat cables without 4-wire conditioning.
- Sense duct temperatures in European building automation where Pt1000 is the regional default.
- Measure heat-pump and chiller compressor temperatures with calibration that survives factory-to-field handling.
- Replace expensive Pt100 wiring schemes in retrofits where the controller already has a 1k-range RTD input.
Best for
- HVAC
- Building automation
- Long cable runs
Key specifications
- Operating limits: Check the exact manufacturer's datasheet (A family name does not establish voltage, current, temperature or timing limits.)
- Pin assignment: Match the complete part and package code (A similar name or function does not guarantee the same wiring.)
- Mechanical fit: Use the exact package drawing (Check pad layout, dimensions and viewing direction before building.)
When not to use it
- Where the controller hardware only supports Pt100 (older 100 Ω-range circuitry) — a Pt1000 will read off-scale; convert or replace input boards.
- Where excitation power must be sub-microwatt — the higher resistance multiplies self-heating per mA² × 10×; choose lower excitation current.
Common mistakes
- Mixing Pt100 and Pt1000 in the same controller channel without changing the lookup table — every reading is wildly wrong (10× scale error).
- Pulsing high excitation current to 'measure faster' — joule heating raises element temperature and biases the reading hot for tens of seconds afterward.
Where you will find it
- A Siemens Synco 700 building controller polls Pt1000 sensors throughout an office tower's HVAC ducts: a 30 m cable from each AHU to the controller adds about 0.6 Ω of copper resistance, contributing only ±0.15 °C error on the Pt1000, making 2-wire installation acceptable and saving tens of metres of fourth-wire cable per duct.
- A heat-pump's evaporator-coil temperature is measured with a clip-on Pt1000 sensor (TE Connectivity 332-9911-00): the 1 000 Ω element is monitored over 5 m of stranded copper from the field-mount controller, with the result driving the defrost-cycle decision when the coil drops below −5 °C.
- A solar-thermal panel array uses Pt1000 sensors in each panel's manifold: the long DC-bus wiring (sometimes 50 m to the differential controller) makes 2-wire Pt1000 the right trade-off — the 0.5 °C lead-resistance error is well below the differential signal needed to start the circulator pump.
A short history
Platinum resistance sensors turn a predictable resistance change into a temperature measurement. The designation here means a nominal 1000 Ω at 0 °C. Accurate instruments must also account for lead resistance, excitation-current self-heating and the sensor's specified tolerance class; the nominal value alone does not set accuracy.