Carrier 19XL specifications Lubrication System

Fig. 4 Ð Lubrication System

journal bearings within the bearing housing. The oil then drains into the oil reservoir at the base of the compressor. The PIC (Product Integrated Control) measures the temperature of the oil in the sump and maintains the temperature during shut- down (see Oil Sump Temperature Control section, page 32). This temperature is read on the LID default screen.

During the chiller start-up, the PIC will energize the oil pump and provide 15 seconds of prelubrication to the bear- ings after pressure is veri®ed before starting the compressor. During shutdown, the oil pump will run for 60 seconds to post-lubricate after the compressor shuts down. The oil pump can also be energized for testing purposes in the Control Test.

Ramp loading can slow the rate of guide vane opening to minimize oil foaming at start-up. If the guide vanes open quickly, the sudden drop in suction pressure can cause any refrigerant in the oil to ¯ash. The resulting oil foam cannot be pumped efficiently; therefore, oil pressure falls off and lubrication is poor. If oil pressure falls below 15 psid (103 kPad) differential, the PIC will shut down the compressor.

Oil Reclaim System Ð The oil reclaim system oper- ates to return oil back to the oil reservoir by recovering it from 2 areas on the chiller. The primary area of recovery is from the guide vane housing. Oil also is recovered, along with refrigerant, from the cooler.

Any refrigerant that enters the oil reservoir/transmission area is ¯ashed into gas. The demister line at the top of the

casing will vent this refrigerant into the suction of the com- pressor. Oil entrained in the refrigerant is eliminated by the demister ®lter.

DURING NORMAL CHILLER OPERATION, oil is entrained with the refrigerant. As the compressor pulls the refrigerant into the guide vane housing to be com- pressed, the oil will normally drop out at this point and fall to the bottom of the housing where it accumulates. Us- ing discharge gas pressure to power an eductor, the oil is vacuumed from the housing by the eductor and is dis- charged into the oil reservoir. Oil and refrigerant are also recovered from the top of the cooler refrigerant level and are discharged into the guide vane housing. The oil will drop to the bottom of the guide vane housing and be recovered by the eductor system.

DURING LIGHT LOAD CONDITIONS, the suction gas into the compressor does not have enough velocity to return oil, which is ¯oating in the cooler back to the compressor. In addition, the eductor may not have enough power to pull the oil from the guide vane housing back into the oil reservoir due to extremely low pressure at the guide vanes. Two so- lenoids, located on the oil reclaim piping, are operated so that the eductor can pull oil and refrigerant directly from the cooler and discharge the mixture into the oil reservoir. The oil reclaim solenoids are operated by an auxiliary contact integral to the guide vane actuator. This switchover of the solenoids occurs when the guide vanes are opened beyond 30 degrees from the closed position.

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