Automatic Pressure Differencial Controller?
General:

Pressure differencial controller is a safety device in order to prevent compressor because of low lubrication oil pressure of compressor. If in
60 seconds after compressor starting, it still maintains low lubrication oil pressure, the pressure difference controller will start to cut off to ensure system safety.

Installation:

It must be installed at a small vibration position. The pressure chamber marked "Low pressure" must be connect to low pressure side (crankcase of compressor). Another pressure chamber marked "high pressure" must connect to outlet of lubrication oil pump.
Push reset button first after power supply. To reset because of system that leading to controller cut off, it have to be resetted after 5 minutes. Otherwise, it won't function. The factory setting point is 0.1Mpa.
When wiring, comply with electic regulation and power supply requirement in order to avoid damages.
Factory setting is under 380V of power supply. If you want to use 220V power supply, you must disconnect D1 and X, then connects D2 and X terminal.