Carrier 23XL Specifiche Scaricare il pdf (Pagina 59)

Carefully make all regular preliminary and running sys-

tem checks. Perform a Control Test before start-up. If the oil

level appears abnormally high, the oil may have absorbed

refrigerant. Frame 4 machines are able to start with an ab-

normally high oil level. Make sure that the oil temperature

is above refrigerant temperature plus 35° F (19° C) (Frame

1 and 2 machines only).

NOTE: Frame 4 machines do not have an oil heater.

Cold Weather Operation — When the entering con-

denser water drops very low, to a minimum of 55 F (13 C),

the PIC can automatically cycle the cooling tower fans off to

keep the temperature up. Piping may also be arranged to by-

pass the cooling tower.

Slide Valve Operation — Manual operation of the slide

valve to check control operation, or to control the valve in

an emergency operation, is possible by overriding the manual

slide valve count. Access the Status01 table on the LID and

highlight MANUAL SLIDE VALVE COUNT. To control slide

valve movement, enter a desired count value. The MANUAL

SLIDE VALVE COUNT has an allowable input range of plus

or minus 20 to provide up to 10 seconds of slide valve move-

ment in the selected direction. If the counts are positive then

the slide valve position will increase to load the compressor

and vice versa. To release the valve to PIC control press the

RELEASE

softkey.

NOTE: The valve can be increased with manual control to

override the pulldown rate during start-up. However, motor

current above the electrical demand setting, capacity over-

rides, and chilled water below control point will override the

manual count and decrease the slide valve position. For de-

scriptions of capacity overrides and set points, see the Con-

trols section.

Entering a 0 count value will cause the slide valve to main-

tain a HOLD state. In this condition, the slide valve will re-

spond to maintain the chilled water (DT) temperature when

the override occurs.

Refrigeration Log — A refrigeration log, such as the

one shown in Fig. 40, provides a convenient checklist for

routine inspection and maintenance, and provides a continu-

ous record of machine performance. It is an aid in sched-

uling routine maintenance and in diagnosing machine

problems.

Keep a record of the machine pressures, temperatures, and

liquid levels on a sheet similar to that shown. Automatic re-

cording of PIC data is possible through the use of CCN de-

vices such as the Data Collection module and a Building Su-

pervisor. Contact your Carrier representative for more

information.

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Carrier 23XL Specifiche Pagina 59

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