Occupancy Schedule; Safety Controls - Carrier 19XR Start-Up, Operation And Maintenance Instructions Manual

Figure 17 shows a schedule for a typical office building
with a 3-hour, off-peak, cool-down period from midnight
to 3 a.m., following a weekend shutdown. Holiday periods
are in an unoccupied state 24 hours per day. The building
operates Monday through Friday, 7:00 a.m. to 6:00 p.m., and
Saturdays from 6:00 a.m. to 1:00 p.m. This schedule also
includes the Monday midnight to 3:00 a.m. weekend cool-
down schedule.
NOTE: This schedule is for illustration only and is not in-
tended to be a recommended schedule for chiller operation.
Whenever the chiller is in the LOCAL mode, it uses
Occupancy Schedule 01 (OCCPC01S). When the chiller is
in the ICE BUILD mode, it uses Occupancy Schedule 02
(OCCPC02S). When the chiller is in CCN mode, it uses
Occupancy Schedule 03 (OCCPC03S).
The CCN SCHEDULE NUMBER is configured on the
NET_OPT display screen, accessed from the EQUIPMENT
CONFIGURATION table. See Table 2, Example 14.
SCHEDULE NUMBER can be changed to any value from
03 to 99. If this number is changed on the NET_OPT screen,
the operator must go to the ATTACH TO NETWORK DE-
VICE screen to upload the new number into the SCHED-
ULE screen. See Fig. 16.
Safety Controls —
The PIC II monitors all safety con-
trol inputs and, if required, shuts down the chiller or limits
the guide vanes to protect the chiller from possible damage
from any of the following conditions:
• high bearing temperature
• high motor winding temperature
• high discharge temperature
• low discharge superheat*
• low oil pressure
• low cooler refrigerant temperature/pressure
• condenser high pressure or low pressure
• inadequate water/brine cooler and condenser flow
• high, low, or loss of voltage
• ground fault
• voltage imbalance
• current imbalance
• excessive motor acceleration time
• excessive starter transition time
• lack of motor current signal
• excessive motor amps
• excessive compressor surge
• temperature and transducer faults
*Superheat is the difference between saturation temperature
and sensible temperature. The high discharge temperature
safety measures only sensible temperature.
Starter faults or optional protective devices within the starter
can shut down the chiller. The protective devices you
have for your application depend on what options were
purchased.
If compressor motor overload occurs, check the motor
for grounded or open phases before attempting a
restart.
If the PIC II control initiates a safety shutdown, it dis-
plays the reason for the shutdown (the fault) on the CVC
display screen along with a primary and secondary message,
energizes an alarm relay in the starter, and blinks the alarm
light on the control panel. The alarm is stored in memory
and can be viewed on the ALARM HISTORY and
ISM_HIST screens on the CVC, along with a message for
troubleshooting. If the safety shutdown was also initiated by
a fault detected in the motor starter, the conditions at the
time of the fault will be stored in ISM_HIST.
To give more precise information or warnings on the chill-
er's operating condition, the operator can define alert limits
on various monitored inputs. Safety contact and alert limits
are defined in Table 3. Alarm and alert messages are listed
in the Troubleshooting Guide section, page 69.
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