The P2546C-OPR and P2546D-OPR share the same proven cup-rotor geometry and measurement characteristics. Their primary difference is the electrical output. Selecting the correct model therefore depends mainly on the available datalogger input, the required wiring and whether an existing P2546A-OPR installation is being upgraded.
A common measurement platform
Both models are three-cup anemometers developed for wind-resource assessment, wind-turbine power-performance measurements and meteorological monitoring. They share the same aerodynamic concept and classification basis, while using different methods to convert rotor movement into an electrical frequency signal.
In both cases, wind speed is determined from the output frequency. The choice between the models is therefore primarily an interface decision rather than a choice between two different aerodynamic measurement principles.
P2546C-OPR: low-level AC sine-wave output
The P2546C-OPR uses permanent magnets mounted on the rotating shaft to induce a voltage in an internal coil. This creates a low-level AC sine-wave signal with a frequency proportional to wind speed.
The sensor is self-powered and does not require an external power supply. The datalogger must, however, provide a suitable low-level AC or frequency input. Both the signal frequency and its voltage amplitude vary with rotor speed, but only the frequency is used to determine wind speed.
The P2546C-OPR is normally the natural choice when the measurement system already has an input designed for a coil anemometer or another low-level AC sensor.
P2546D-OPR: electronic open-collector output
The P2546D-OPR uses an electronic switching circuit to produce an NPN open-collector output. The frequency of the switching signal is proportional to wind speed and is read by a counter or digital frequency input on the datalogger.
The anemometer itself is self-excited, but an open-collector connection requires a pull-up resistor and a suitable voltage or excitation supplied through the datalogger circuit. WindSensor’s application note recommends checking the datalogger documentation and shows typical wiring with an external pull-up resistor.
The P2546D-OPR is also the recommended direct replacement for the discontinued P2546A-OPR reed-switch version. The exact wiring and datalogger configuration should still be checked before replacing an existing sensor.
Quick comparison
| Requirement | P2546C-OPR | P2546D-OPR |
|---|---|---|
| Output type | Low-level AC sine wave | NPN open collector |
| Typical datalogger input | Low-level AC or frequency input | Counter or digital frequency input |
| External sensor power supply | Not required | Not required for the sensor |
| Additional interface requirement | Input suitable for a low-level AC signal | Pull-up resistor and datalogger excitation/supply |
| Replacement for P2546A-OPR | Not the direct replacement | Recommended direct replacement |
Which model should you choose?
- Choose the P2546C-OPR when the datalogger has a suitable low-level AC input or the installation is already designed for a coil-output anemometer.
- Choose the P2546D-OPR when the datalogger has a counter or digital frequency input that can be configured with the required pull-up circuit.
- For replacement of a discontinued P2546A-OPR, start with the P2546D-OPR and verify the existing wiring and input configuration.
- If the datalogger documentation is unclear, confirm the input requirements before ordering.
The measurement performance remains the priority
The signal interface must be compatible with the data-acquisition system, but it should not be considered in isolation. Calibration, classification, installation geometry, boom configuration and the complete measurement chain all contribute to the quality and uncertainty of the final wind-speed data.
Review the full specifications for the P2546C-OPR and P2546D-OPR, or contact WindSensor if you need help matching an anemometer to your datalogger.