Operating instructions
13
2.3.4 - Motor/oil refrigeration cooling cycle
The motor and the lubricating oil are cooled by liquid
refrigerant taken from the bottom of the condenser vessel
(see Fig. 3 - “Typical 19XR unit diagram”).
Flow of refrigerant is maintained by the pressure differential
that exists due to compressor operation. After the refrigerant
flows past a filtration system, a filter, and a sight glass/
moisture indicator, the flow is split between motor cooling
and oil cooling systems.
Flow to the motor flows through an orifice and into the
motor. Once past the orifice, the refrigerant is directed
over the motor by a spray nozzle. The refrigerant collects
in the bottom of the motor casing and then is drained back
into the cooler through the motor refrigerant drain line.
A check valve in this line maintains a higher pressure in
the motor shell than in the cooler/oil sump. The motor is
protected by a temperature sensor imbedded in the stator
windings.
(for 19XRV particulars refer to Fig. 48)
1. FLASC chamber
2. Condenser water
3. Condenser
4. Condenser isolation valve
5. Transmission
6. Diuser
7. Guide vane motor
8. Motor
9. Guide vanes
10. Impeller
11. Compressor
12. Back pressure orice
13. Oil cooling
14. Oil lter
15. Oil pump
16. Stator
17. Rotor
18. Refrigerant cooling isolation valve
19. Float valve chamber
20. Filter drier
21. Oriced tting
22. Moisture/ow indicator
23. Oriced tting
24. Thermostatic expansion valves (TXV)
25. Distribution pipe
26. Cooler isolation valve
27. Evaporator
28. Chilled water
29. Refrigerant liquid
30. Refrigerant vapour
31. Refrigerant liquid/vapour
If the temperature exceeds the authorised threshold, a
priority command limits the unit capacity control. If the
temperature exceeds the threshold of 5.5°C, the guide
vanes are closed. If the temperature rises above the safety
limit, the compressor will shut down.
Refrigerant that flows to the oil cooling system is regulated
by thermostatic expansion valves (TXVs). The TXVs
regulate flow into the oil/refrigerant plate and frame-type
heat exchanger. The expansion valve bulbs control oil
temperature to the bearings. The refrigerant leaving the
heat exchanger then returns to the cooler.