Oil pressure switch logic

[Cornishman]

I found an oil leak that appeared to come throu the center of the engine oil pressure switch, hence bought a replacement. However the one I got is from a BMW 318 and the light flickers under acceleration. The manual suggests tick over pressure of 1.8 to 2 bar, but the switch appears to operate at 0.05 to 0.15 bar. Does anyone know the logic for this? Also, why does engine oil pressure fall under acceleration?
Clearly I will try to get the correct switch, I just wonder what the logic is, and ideas?
Thanks C

 

[deQuincey]

maybe some light from my experience, with an additional extra gauge for oil pressure

when i start the car in cold engine the oil pressure goes up up to 3,2 bar and maintains there no matter what the changes in speed are
but with warm engine iddle is around 2,5 bar, and acceleration can bring the needle up to 4,5 bar