Carrier AquaEdge 19XR series Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XR series: Installation instructions Start-up, operation and maintenance instructions

Contents

Carrier AquaEdge 19XR series Start-up, Operation And Maintenance Instructions Manual Manual pdf 12 page image

12Flow to the motor cooling system passes through an orificeand into the motor. Once past the orifice, the refrigerant is di-rected over the motor by a spray nozzle. The refrigerant col-lects in the bottom of the motor casing and is then drained backinto the cooler through the motor refrigerant drain line. An ori-fice (in the motor shell) maintains a higher pressure in themotor shell than in the cooler. The motor is protected by a tem-perature sensor imbedded in the stator windings. An increase inmotor winding temperature past the motor override set pointoverrides the temperature capacity control to hold, and if themotor temperature rises 10 F (5.5 C) above this set point, theProduct Integrated Control II (PIC II) controls close the inletguide vanes. If the temperature rises above the safety limit, thecompressor shuts down.Refrigerant that flows to the oil cooling system is regulatedby thermostatic expansion valves (TXVs). The TXVs regulateflow into the oil/refrigerant plate and frame-type heat exchang-er (the oil cooler in Fig. 4 and 5). The expansion valve bulbscontrol oil temperature to the bearings. The refrigerant leavingthe oil cooler heat exchanger returns to the chiller cooler.VFD COOLING CYCLEThe unit-mounted variable frequency drive (VFD) typicallyhas PIC III controls. The only unit-mounted drive availablewith PIC II controls is the 575-v input drive.The 575-v unit-mounted variable frequency drive (VFD) iscooled in a manner similar to the motor and oil cooling cycle(Fig. 4 and 5).If equipped with a unit-mounted VFD, the refrigerant linethat feeds the motor cooling and oil cooler also feeds the heatexchanger on the unit-mounted VFD. Refrigerant is meteredthrough an orifice. The refrigerant leaving the heat exchangerreturns to the cooler.LUBRICATION CYCLESummary — The oil pump, oil filter, and oil cooler makeup a package located partially in the transmission casing of thecompressor-motor assembly. The oil is pumped into a filter as-sembly to remove foreign particles and is then forced into anoil cooler heat exchanger where the oil is cooled to proper op-erational temperatures. After the oil cooler, part of the flow isdirected to the gears and the high speed shaft bearings; the re-maining flow is directed to the motor shaft bearings. Oil drainsinto the transmission oil sump to complete the cycle (Fig. 6 and7).Details — Oil is charged into the lubrication system througha hand valve. Two sight glasses in the oil reservoir permit oillevel observation. Normal oil level is between the middle of theupper sight glass and the top of the lower sight glass when thecompressor is shut down. The oil level should be visible in atleast one of the 2 sight glasses during operation. Oil sump tem-perature is displayed on the ICVC (International Chiller VisualController) default screen. During compressor operation, theoil sump temperature ranges between 125 and 150 F (52 and66 C).The oil pump suction is fed from the oil reservoir. An oilpressure relief valve maintains 18 to 25 psid (124 to 172 kPad)differential pressure in the system at the pump discharge. Forcompressors equipped with rolling element bearings, a range of18 to 40 psid (124 to 172 kPad) is normal. This differentialpressure can be read directly from the ICVC default screen.The oil pump discharges oil to the oil filter assembly. This filtercan be closed to permit removal of the filter without drainingthe entire oil system (see Maintenance sections, pages 93-98,for details). The oil is then piped to the oil cooler heat exchang-er. The oil cooler uses refrigerant from the condenser as thecoolant. The refrigerant cools the oil to a temperature between120 and 140 F (49 to 60 C).As the oil leaves the oil cooler, it passes the oil pressuretransducer and the thermal bulb for the refrigerant expansionvalve on the oil cooler. The oil is then divided. Part of the oilflows to the thrust bearing, forward pinion bearing, and gearspray. The rest of the oil lubricates the motor shaft bearings andthe rear pinion bearing. The oil temperature is measured in thebearing housing as it leaves the thrust and forward journalbearings or on the bearing race if the compressor is equippedwith rolling element bearings. The oil then drains into the oilreservoir at the base of the compressor. The PIC II (Product In-tegrated Control II) measures the temperature of the oil in thesump and maintains the temperature during shutdown (see OilSump Temperature and Pump Control section, page 52). Thistemperature is read on the ICVC default screen.