What is an oil pressure sender? What is it used For?
An oil pressure sender is a type of oil pressure sensor. An oil pressure sender is a device that senses the oil pressure of an engine and transmits it to the engine or machine controller. It is used as a generator protection device, to display the oil pressure to a user or for logging and diagnostic purposes. Unlike an oil pressure switch, it can display a range of readings.
How does it work?
The oil pressure sender transmits the pressure by converting the pressure value into an electrical signal, often resistive. As well as changing resistance, they can also be designed to output different voltages. In this case the resistance of the sender varies depending on the oil pressure. Different brands and types of senders will have values corresponding to different pressures, so its important when replacing a sender to replace with the same model, one that looks similar might not have the same electrical characteristics, for example the graphs below show a Murphy 7 Bar vs a VDO 10 Bar Curve.
Either an engines ECU or a generator control module can read the resistance or voltage output and convert this back to a pressure reading. This pressure reading is then used to protect the engine, display a value to a user and possibly logged in the controllers memory.