1. What Is a Pt100 Sensor?
A Pt100 sensor is a platinum RTD with a nominal resistance of 100 ohms at 0°C. It measures temperature by detecting changes in the electrical resistance of its platinum sensing element.
What Does Pt100 Mean?
“Pt” refers to platinum and “100” refers to its 100 Ω resistance at 0°C. As temperature rises, the resistance increases, allowing the controller to calculate the temperature.
2. How Does a Pt100 Temperature Sensor Work?
A Pt100 measures temperature through the resistance change of its platinum element. The compressor controller measures the resistance and converts it into a temperature value.
Pt100 Resistance
A standard Pt100 has about 100 Ω at 0°C and 138.5 Ω at 100°C. This predictable relationship allows the sensor to provide continuous temperature monitoring.
3. Where Is a Pt100 Temperature Sensor Used in an Air Compressor?
A Pt100 temperature sensor is installed at a temperature monitoring point specified by the compressor design. Common locations include the airend discharge area and lubricating oil circuit.
The exact installation point varies by compressor model, so replacement requires matching the original sensor position, probe dimensions, and connection.
4. What Happens When a Pt100 Temperature Sensor Fails?
A faulty Pt100 can send an incorrect temperature signal to the compressor controller, causing abnormal readings, alarms, or unexpected shutdowns.
Common Failure Symptoms
- Incorrect or unstable temperature readings
- Open- or short-circuit alarms
- Temperature values that do not respond normally
- Unexpected compressor shutdowns
Check the sensor wiring and connectors before replacing the sensor because connection faults can cause similar symptoms.
5. What Is the Difference Between Pt100 and Pt1000?
The main difference is resistance at 0°C. A Pt100 has 100 Ω, while a Pt1000 has 1,000 Ω. Both use platinum RTD technology but require compatible controller inputs.
| Feature | Pt100 | Pt1000 |
|---|---|---|
| Resistance at 0°C | 100 Ω | 1,000 Ω |
| Material | Platinum | Platinum |
| Principle | Resistance change | Resistance change |
| Lead resistance effect | Higher | Lower |
Are They Interchangeable?
Not normally. Always match the sensor type required by the compressor controller before replacing a Pt100 with a Pt1000.
For a detailed comparison, see our Pt1000 Temperature Sensor guide.
6. How to Test a Pt100 Temperature Sensor?
You can perform a basic Pt100 test with a digital multimeter by measuring its resistance and comparing the result with the expected value at the measured temperature.
Basic Test
- Shut down and isolate the compressor.
- Disconnect the sensor from the controller.
- Set the multimeter to resistance (Ω).
- Measure the sensor resistance.
- Compare the reading with the expected Pt100 value.
A standard Pt100 should measure approximately 100 Ω at 0°C and 138.5 Ω at 100°C.
7. What Are the Different Pt100 Sensor Types and Wiring Configurations?
Pt100 sensors are available with different probe designs and 2-wire, 3-wire, or 4-wire configurations.
2-Wire, 3-Wire and 4-Wire
- 2-wire: Simple, but lead resistance affects the measurement.
- 3-wire: Compensates for most lead resistance and is common in industrial applications.
- 4-wire: Provides the highest resistance-measurement accuracy.
For replacement, match the original wiring configuration with the compressor controller.
Probe Designs
Pt100 probes can also differ in length, diameter, mounting thread, connector, and cable length. These dimensions must match the original installation.
8. How to Choose the Right Pt100 Temperature Sensor for an Air Compressor?
Choose a replacement Pt100 by matching its electrical specification, wiring, dimensions, connection, temperature range, and compressor controller compatibility.
Key Selection Factors
Before ordering, check:
- Pt100 sensor type
- 2-wire, 3-wire, or 4-wire configuration
- Probe length and diameter
- Mounting thread and connector
- Cable length
- Temperature range
- Original part number and compressor model
Providing the original sensor details helps confirm compatibility and reduces the risk of ordering the wrong replacement.
