Pressure difference controner is a safety device in order to prevent bushing damaging because of low lubrication oil pressure of compressor．
　　If in 60seconds after compressor starting，system can become suiting oil pressure，pressure dlfference controller will start to cut off to ensure system safety．

　　It is with two pressure sensor（bellows）．Tow bellows senses two different pressure and become a force，it the force is lower than preseting value，one switcher will cut on a heater in timer－delay，in a setting time （around 60 second），lead to timer－delay start and cut off compressor power supply．Compressor stopped，at the same time；heater stopped．There is a manual reset device in timer－delay of pressure difference controller．When compressor stopped because of lower oil pressure，the controller will cut off and can’t automatic reset．When put the manual reset button，the switcher in timer-delay will cut on and then compressor running．
　 On out-shell of pressure difference controller，there is a test button for test reliability oy timer－delay．When compressor running，push the testing button by arrow direction，and keep the enough time（it must be longer than delaying time），if can cut off compressor power supply，it is say the controller working well．

　　 1．It must be installed at low vibration position．The pressure chamber marked”low pressure”must connect wlth low pressure side（shaft box），another pressure chamber marked ”high pressure” must connect with outlet of lubrication pump．
　　 2．It should push reset button first affer connect wlth power．If want to reset while system reason lead to controller cut off，it have to reset alter heater cooling around 5 minutes．Otherwise，it can’t reset． The preset point is 0.1Mpa when exiting factory.
　　 3．When connect with electrical system，it must be connected by electrical cycle and power supply requirement in order to avoid damaging electrical system．
　　 4．Controllerf Connected under 380Vofpower supply，if you want to use 220V power supply，you must disconnect D1 and X，then connects D2 and X terminal．