can you tell us more about the application?
i am not sure if a "3 point control relay" is a universal term....could be different in some textbooks
From what I can gather 3 point relay control or hi / lo control, is used as an alternative for temperature control e.g. for the control of an air damper against full PID modulating control.
The max speed must be more than enough to satisfy the process. Easiest way is to have one thermostat controlling the low speed function and a second TS bringing on the high speed winding if the motor low speed is insufficient (after a short time delay) to satisfy temperature.
Two stage control is a more common term, if the above describes your intent.
