Carrier 17/19EX - Manual (Page 51)

Volatile Memory
Volatile memory is memory incapable of being sustained if power is lost and subsequently
restored.
General
The 17/19EX hermetic centrifugal liquid chiller contains a microprocessor-based control
center that monitors and controls all operations of the machine. The microprocessor control
system matches the cooling capacity of the machine to the cooling load while providing state-of-
the-art machine protection. The system controls cooling load within the set point plus the
deadband by sensing the leaving chilled water or brine temperature, and regulating the inlet
guide vane via a mechanically linked actuator motor. The guide vane is a variable flow prewhirl
assembly that controls the refrigeration effect in the cooler by regulating the amount of
refrigerant vapor flow into the compressor. An increase in guide vane opening increases
capacity. A decrease in guide vane opening decreases capacity. Machine protection is provided
by the processor which monitors the digital and analog inputs and executes capacity overrides
or safety shutdowns, if required.
CAUTION CAUTION
!
The memory of the PSIO and LID modules are volatile. If the battery in a module
is removed or damaged, all programming will be lost.