York Millennium YCAS 310, Установка, эксплуатация и обслуживание

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YORK INTERNATIONAL
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This message indicates that the chiller is operating un-
der load limiting from an ISN System through the RS-
485 input. This feature controls loading under a num-
ber of ISN programmable values, enhancing the flex-
ibility of controlling the chiller to obtain desired chiller
loading within the overall building control scheme.
Memory Backup Battery Fault:
The Microprocessor Board contains a Real Time Clock
(RTC) I.C. Chip with an internal battery back-up. This
battery back-up assures that any programmed values
(setpoints, etc.), clock, all fault information, and accu-
mulated information such as starts/run time, etc. stored
in the RTC memory is not lost when a power failure
occurs, regardless of length of the power loss.
The battery is a 10 year lithium type. The life of the
battery will depend upon whether the Real Time Clock’s
internal clock circuit is energized. With the clock OFF,
a rated life of approximately 10 years can be expected.
With the clock ON, approximately 5 years.
The clock is turned ON and OFF by a jumper on the
Microprocessor Board. While the chiller is operating,
the clock must be ON. Otherwise the internal clock on
the microprocessor will not be active and the micro can
not keep track of time, although all other functions will
operate normally. Failure to turn the Clock ON could
result in the chiller not starting due to the time frozen
on the clock falling outside the START/STOP time win-
dow that is programmed in the DAILY SCHEDULE.
If the chiller is shut down for extended periods of
months, it may be desirable to disable the clock to save
battery life. The clock can then be reactivated and re-
programmed when the chiller is returned to service.
NOTE: All programmed values and stored data,
otherthan the internal clock time-keeping, will
be maintained in memory regardless of whether
the clock is on or off and regardless of the
length of the power failure.
To disable the clock, place the jumper (Fig. 39) in the
OFF position. To activate it, place the jumper in the ON
position.
On power-up the microprocessor will check the Real
Time Clock (RTC Chip) battery to assure that the inter-
nal battery is still operational. This is accomplished by
performing an RTC RAM location check. As long as
the battery checks out, the micro will continue on with
business without operation.
If a check is made and the batter has failed, the micro-
processor will not allow the chiller to run and the
! ! W A R N I N G ! !
! ! L O W B A T T E R Y ! !
!!WARNING!! !!LOW BATTERY!! message will appear.
Under low battery conditions, the only way to run the
chiller is to press the “MANUAL OVERRIDE” key (Sec-
tion 7.4). The “MANUAL OVERRIDE” key will function
differently than it does in service situations where it
overrides the daily schedule for only 30 minutes. In a
low battery condition, the “MANUAL OVERRIDE” key
will zero out the daily schedule to allow unlimited op-
eration regardless of the time on the internal clock.
Default values will also be loaded into memory for all
setpoints and cut-outs. These may require reprogram-
ming to assure they meet the chiller operating require-
ments for operation board 30 minutes. In addition, the
low battery message which is displayed for this condi-
tion will disappear.
NOTE: If a power failure should again occur, the above
process will again need to be repeated to bring
the chiller back on line.
In the unlikely event the low battery message should
ever appear, it will require the RTC chip U13 on the
Microprocessor Board (Fig. 39) to be replaced. Care
should be taken to assure that the chip is properly in-
stalled. Pin 1 (dimple in the top part of the chip) must
be oriented as shown in Fig. 39. The part number of
the RTC Chip is 031-00955-000.
2.3 ANTICIPATION CONTROL STATUS MESSAGES
Anticipation controls are built into the software to pre-
vent safety shutdowns by automatically overriding the
temperature controls if system conditions approach
safety thresholds. This avoids total loss of cooling re-
sulting from a lockout by a safety control.
Anticipation controls monitor discharge pressure, mo-
tor current and suction temperature for each compres-
sor and, if maximum limits are approached, the slide
valve loading of the respective compressor will be re-
duced to avoid exceeding the limit.
Displays of anticipation safety control messages and
their meanings are as follows:
Discharge Pressure Limiting:
Discharge Pressure Limiting takes effect when compres-
sor discharge pressure nears the point at which the high
pressure cutout would shut the system down. When the
above message appears, discharge pressure has ex-
ceeded the programmable threshold and the compressor
is being unloaded in an effort to prevent shutdown on the
high pressure cutout. The operation of this safety is impor-
tant if condenser coils become dirty, if there is a problem
with the condenser fan operation, or if extreme ambient or
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