Standby Chiller Configuration and Operation — The con-
figured standby chiller is identified as such by having the
LEAD/LAG SELECT configured to the value of ‘‘3.’’ The
standby chiller can only operate as a replacement for the lag
chiller if one of the other two chillers is in an alarm (*) con-
dition (as shown on the LID panel). If both lead and lag chill-
ers are in an alarm (*) condition, the standby chiller shall
default to operate in CCN mode based on its configured Oc-
cupancy Schedule and remote contacts input.
Lag Chiller Start-Up Requirements — Before the lag chiller
can be started, the following conditions must be met:
1. Lead chiller ramp loading must be complete.
2. Lead chiller CHILLED WATER temperature must be greater
than the CONTROL POINT plus 1/2 the WATER/BRINE
DEADBAND.
NOTE: The chilled water temperature sensor may be the leav-
ing chilled water sensor, the return water sensor, the com-
mon supply water sensor, or the common return water sen-
sor, depending on which options are configured and enabled.
3. Lead chiller ACTIVE DEMAND LIMIT value must be
greater than 95% of full load amps.
4. Lead chiller temperature pulldown rate of the CHILLED
WATER temperature is less than 0.5° F (0.27° C) per minute.
5. The lag chiller status indicates it is in CCN mode and is
not faulted. If the current lag chiller is in an alarm con-
dition, then the standby chiller becomes the active lag chiller,
if it is configured and available.
6. The configured LAG START TIMER entry has elapsed.
The LAG START TIMER shall be started when the lead
chiller ramp loading is completed. The LAG STARTTIMER
entry is accessed by selecting Lead/Lag from the Equip-
ment Configuration table of the Service menu.
When all of the above requirements have been met, the
lag chiller is forced to a START mode. The PIC control then
monitors the lag chiller for a successful start. If the lag chiller
fails to start, the standby chiller, if configured, is started.
Lag Chiller Shutdown Requirements — The following con-
ditions must be met in order for the lag chiller to be stopped.
1. Lead chiller COMPRESSOR MOTOR LOAD value is
less than the lead chiller percent capacity plus 15%.
NOTE: Lead chiller percent capacity = 100 – LAG PER-
CENT CAPACITY
The LAG PERCENT CAPACITY value is configured on
the Lead/Lag Configuration screen.
2. The lead chiller chilled water temperature is less than the
CONTROL POINT plus 1/2 of the WATER/BRINE
DEADBAND.
3. The configured LAG STOP TIMER entry has elapsed.
The LAG STOP TIMER is started when the CHILLED
WATER TEMPERATURE is less than the CHILLED WA-
TER CONTROL POINT plus 1/2 of the WATER/BRINE
DEADBAND and the lead chiller COMPRESSOR MO-
TOR LOAD is less than the lead chiller percent capacity
plus 15%. The timer is ignored if the chilled water tem-
perature reaches 3° F (1.67° C) below the CONTROL
POINT and the lead chiller COMPRESSOR MOTOR
LOAD value is less than the lead chiller percent capacity
plus 15%.
FAULTED CHILLER OPERATION — If the lead chiller
shuts down on an alarm (*) condition, it stops communica-
tion to the lag and standby chillers. After 30 seconds, the lag
chiller will now become the acting lead chiller and will start
and stop the standby chiller, if necessary.
If the lag chiller faults when the lead chiller is also faulted,
the standby chiller reverts to a stand-alone CCN mode of
operation.
If the lead chiller is in an alarm (*) condition (as shown
on the LID panel), the RESET softkey is pressed to clear the
alarm, and the chiller is placed in the CCN mode, the lead
chiller will now communicate and monitor the RUN STA-
TUS of the lag and standby chillers. If both the lag and standby
chillers are running, the lead chiller will not attempt to start
and will not assume the role of lead chiller until either the
lag or standby chiller shuts down. If only one chiller is run-
ning, the lead chiller will wait for a start request from the
operating chiller. When the configured lead chiller starts, it
assumes its role as lead chiller.
LOAD BALANCING — When the LOAD BALANCE OP-
TION is enabled, the lead chiller will set the ACTIVE DE-
MAND LIMIT in the lag chiller to the lead chiller’s COM-
PRESSOR MOTOR LOAD value. This value has limits of
40% to 100%. When setting the lag chiller ACTIVE DE-
MAND LIMIT, the CONTROL POINT shall be modified to
a value of 3° F (1.67° C) less than the lead chiller’s CON-
TROL POINT value. If the LOAD BALANCE OPTION is
disabled, the ACTIVE DEMAND LIMIT and the CON-
TROL POINT are forced to the same value as the lead chiller.
AUTO. RESTART AFTER POWER FAILURE — When an
autorestart condition occurs, each chiller may have a delay
added to the start-up sequence, depending on its lead/lag con-
figuration. The lead chiller does not have a delay. The lag
chiller has a 45-second delay. The standby chiller has a
90-second delay. The delay time is added after the chiller
water flow verification. The PIC controls ensure that the guide
vanes are closed. After the guide vane position is confirmed,
the delay for lag and standby chiller occurs prior to ener-
gizing the oil pump. The normal start-up sequence then con-
tinues. The auto. restart delay sequence occurs whether the
chiller is in CCN or LOCAL mode and is intended to stag-
ger the compressor motors from being energized simulta-
neously. This will help reduce the inrush demands on the
building power system.
Ice Build Control —
Ice build control automatically
sets the chilled WATER/BRINE CONTROL POINT of the
machine to a temperature where an ice building operation
for thermal storage can be accomplished.
NOTE: For ice build control to properly operate, the PIC
controls must be placed in CCN mode. See Fig. 13 and 14.
The PIC can be configured for ice build operation. Con-
figuration of ice build control is accomplished through en-
tries in the Config table, Ice Build Set Point table, and the
Ice Build Time Schedule table. Figures 13 and 14 show how
to access each entry.
The Ice Build Time Schedule defines the period during
which ice build is active if the ice build option is EN-
ABLED. If the Ice Build Time Schedule overlaps other sched-
ules defining time, then the Ice Build Time Schedule shall
take priority. During the ice build period, the WATER/
BRINE CONTROL POINT is set to the ICE BUILD SET-
POINT for temperature control. The ICE BUILD RECYCLE
OPTION and ICE BUILD TERMINATION entries from a
screen in the Config (configuration) table provide options
for machine recycle and termination of ice build cycle, re-
spectively. Termination of ice build can result from the EN-
TERING CHILLED WATER/BRINE temperature being less
than the ICE BUILD SETPOINT, opening of the REMOTE
CONTACT inputs from an ice level indicator, or reaching
the end of the Ice Build Time Schedule.
31
Summary of Contents for 19EF Series
Page 10: ...Fig 5 19EF Controls and Sensor Locations cont 10...
Page 13: ...Fig 12 19EF Menu Structure 13...
Page 14: ...Fig 13 19EF Service Menu Structure 14...
Page 38: ...Fig 24 19EF Leak Test Procedures 38...
Page 69: ...Fig 36 Electronic PIC Controls Wiring Schematic 69...
Page 70: ...Fig 36 Electronic PIC Controls Wiring Schematic cont 70...
Page 71: ...Fig 37 Machine Power Panel Starter Assembly and Motor Wiring Schematic 71...
