Carrier 19XL User Manual

Page 42

in the motor shell than in the cooler/oil sump. The motor is protected by a temperature sensor

imbedded in the stator windings. Higher motor temperatures (above 125 F [51 C]) energize a

solenoid to provide additional motor cooling. A further increase in temperature past the motor

override set point will override the temperature capacity control to hold, and if the motor

temperature rises 10° F (5.5° C) above this set point, will close the inlet guide vanes. If the

temperature rises above the safety limit, the compressor will shut down.

Refrigerant that flows to the oil cooling system is regulated by a thermostatic expansion

valve. There is always a minimum flow bypassing the TXV, which flows through an orifice. The

TXV valve regulates flow into the oil/refrigerant plate and frame-type heat exchanger. The bulb

for the expansion valve controls oil temperature to the bearings. The refrigerant leaving the heat

exchanger then returns to the cooler.