Bitzer semi hermetic compressor failure

Hello,

Using a system with bitzer semi hermetic compressor 8FC-70.2Y40D for DX air conditioner. AHU is having danfoss electrical expansion valves AKV-20 - 2nos. System is operating with R404A. Unit is designed for 218 kW cooling capacity with evap temp of 4.5 deg c and condensing of 47.6 deg C. Condenser is sea water cooled. Total 4 units. Desgined air inlet is 30 deg C and air outlet of 9 deg C. Actual observed parameters are 26 deg C and 21 deg C. AHU is copper coil with Al fins. Suction pressure at compressor is 3.8 kg/cm2 and discharge pressure is 14 kg/cm2. Oil pressure is 3 kg/cm2.

The unit runs for 2000 hours and after that the compressor breakdown occurs. Winding failure observed. Same problem is observed on all 4 units. Current drawn is also 50 Amp.

Can anybody help to identify the cause of failure.

oil pressure is lower than suction pressure

To elaborate on install monkeys observation: Should the crankcase pressure be too high for the oil pressure regulating valve to increase oil pressure over and above the crankcase pressure, it is indicative of a serious wear problem with the compressor. You will find this and more information on the attached Bitzer bulletin.

http://www.ior.org.uk/ior_/images/pd...ompressors.pdf

Hi
dont just replace the comp . have it opend up and check
i think you will find mechanichal failure that led to electrical failure!!
with a water cooled condenser you should have a regulating valve on water side
check all your settings !
good luck