In the field of temperature sensing, PT100 and PT1000 are the two most common types of Platinum Resistance Temperature Detectors (RTDs). Although they share the same physical principle, they exhibit key differences in practical applications. Below is a detailed comparison:

1. Working Principle 

Both PT100 and PT1000 operate based on the property that the electrical resistance of platinum (Pt) changes predictably with temperature. As temperature rises, the resistance increases; conversely, it decreases as temperature drops. This relationship follows the standard curve defined by the International Electrotechnical Commission (IEC 60751):

Where $R(t)$ is the resistance at temperature $t$, $R_0$ is the nominal resistance at 0°C, and $A$ and $B$ are constants.

2. Nominal Resistance 

• PT100: The “100” indicates that the sensor has a resistance of 100 Ohms ($\Omega$) at 0°C.

• PT1000: Similarly, “1000” represents a resistance of 1000 Ohms ($\Omega$) at 0°C.

  This is the most direct and fundamental difference between the two.

3. Sensitivity and Resolution 

Since the base resistance of a PT1000 is ten times that of a PT100, the absolute change in resistance for the same temperature shift is also ten times greater.

• PT100: Changes by approximately 0.385 $\Omega$/°C.

• PT1000: Changes by approximately 3.85 $\Omega$/°C.

This higher sensitivity allows the PT1000 to provide better resolution, making it easier to measure minute temperature fluctuations precisely. However, this also requires measuring circuits (transmitters) with high stability to handle the higher impedance.

4. Signal Transmission and Lead Wire Effect 

This is a critical engineering distinction:

• PT100: Because its base resistance is low, the resistance of the lead wires (cables) can significantly impact accuracy. Therefore, 3-wire or 4-wire configurations are almost always required to compensate for lead resistance.

• PT1000: With a much higher base resistance, the relative impact of lead wire resistance is much smaller. This often allows for accurate measurements using a simple 2-wire configuration over moderate distances, saving on wiring costs.

5. Application Scenarios 

• PT100: Widely used in industrial environments such as HVAC systems, food processing, and heavy machinery due to its standardized compatibility with most industrial controllers (PLCs).

• PT1000: Preferred for battery-powered applications (due to lower current consumption) and high-precision fields like laboratory research and medical instruments. It is also common in domestic appliances and automotive sensors where 2-wire cabling is preferred.

6. Summary 

The choice between PT100 and PT1000 depends on your specific system requirements, wiring distance, and power budget.