System Start-Up; Sequence Of Operation - Trane IntelliPak CG-SVX02B-EN Installation & Operation Manual

Sequence of Operation

Chiller Control for Comfort Applications
The CGM controls the leaving solution temperature (LST) to
within an adjustable setpoint using deadband control. The
CGM monitors the LST sensor and determines how far
away the temperature is from the leaving solution setpoint
(LSS). The compressors are staged On/Off depending on
where the LST is within the control deadband.
Deadband Calculation
The rate at which capacity stages are added or subtracted
is determined by a control algorithm The CGM control
deadband for comfort applications is a calculated value
based upon the control response setpoint, the difference
between LSS and LST, the number of capacity steps, the
design delta temperature (DDT) of the system, and the
number of capacity steps. The minimum comfort deadband
is 1 degree F. The maximum comfort deadband above or
below the LSS is 10 F for a two stage unit and 5
stage unit.
When the LST is inside the control deadband, the calcula-
tion is cleared and no response is initiated. When the LST
is outside the deadband and the calculated control algo-
rithm value equals 1, a capacity add command is initiated.
Conversely, when the value of the control algorithm equals -
1, a capacity subtract command is initiated. Once a capac-
ity add or subtract command is given and a change in the
compressor staging has been detected, the value of the
control algorithm is reset to 0.
Chiller Freeze Protection
The CGM prevents evaporator fluid from freezing by utiliz-
ing two separate algorithms. One is the evaporator limit
control algorithm which stages compressors "Off" if violated
and the other is the evaporator freeze protection algorithm
which activates auto/manual diagnostics if violated. The
freeze protection function will always operate as long as the
unit is in the Auto mode for both normal cooling applications
and/or ice building modes. A manual reset diagnostic will
occur if all compressors are shut off due to a freeze protec-
tion violation.
The evaporator limit control integrator (ELCI) algorithm cal-
culates a value based upon the low solution temperature
cutout setpoint and the leaving solution temperature. When
the value for ELCI drops below -1, the unit control will re-
duce the chiller capacity by staging down and/or inhibiting a
compressor from operation. After each capacity subtract
command from the capacity control algorithm is issued,
ELCI is increased by 1 and retained. The ELCI is set to 0
any time the leaving solution temperature is greater than or
equal to the low solution temperature cutout (LSC) + 3
Compressors will be prevented from operating until the
leaving solution temperature (LST) is 4
If Pumpdown is enabled and a subtract command is issued,
the circuit will be allow to pumpdown.
If HGBP is enabled (Pumpdown is disabled) and a subtract
command is sent by the ELCI, HGBP operation will be initi-
ated before the last compressor is turned "Off". Once HGBP
has been initiated, all subtract commands sent by the ELCI
will be ignored. If the Leaving Solution Temperature (LST) is
less than the Low Solution Cutout (LSC) + 1
ther prevented from operating or turned "Off".

System Start-Up

Evaporator Freeze Protection Diagnostic
The evaporator freeze protection integrator (EFZ) will start
integrating when the leaving solution temperature or enter-
ing solution temperature is less than the low solution tem-
perature cutout setpoint. Once EFZ integrates up to 30 Sec,
the following diagnostics will occur:
1. If all compressors are off, an auto diagnostic will occur.
2. If any compressors are "On", a manual diagnostic will oc-
Sequence of Operation
o F for a 4
Chiller Control for Ice Building Mode
The CGM provides Ice Building control when a customer
provided field installed binary input is connected to the
CGM or requested by Tracer (TCI only).
The optional Ice building machine has two ice building
modes:
1. One Time Ice Build Mode
2. Continuous Ice Build Mode
o F.
o F above the LSC.
o F, HGBP is ei-
41
All of the compressors will be prevented from operating
until the LST and/or ESTis 4
Once the LST and/or EST is 4
will allow normal unit operation.
cur. All of the compressors will be shutdown and locked
out due to the violation of the evaporator freeze protec-
tion.
Ice Building can be activated by:
Closing the customer provided field installed remote
device, or
Ice building requested by Tracer (TCI only), provided;
Ice machine option is installed, and
Ice building is enabled through the Human Interface
Module
Once the ice building mode is initiated, the unit will run
fully loaded until the entering solution temperature (EST)
equals the ice building termination setpoint (IBTS). After
the IBTS is reached, the unit will transition into the "Ice
Building Complete" mode and turn all compressors "Off"
and the solution pump "Off" (if pump mode is in "Auto").
The unit will remain in the ice build complete status until
the unit is cycled out of the "Ice Building" mode.
Once the ice building mode is initiated, the unit will run
fully loaded until the EST equals the IBTS. After the EST
reaches the IBTS, the unit will transition into the "Ice Re-
build Delay" mode and turn all compressors "Off" and the
solution pump "Off" (if pump mode is in "Auto"). The unit
will remain in the ice rebuild delay status until the Ice Re-
build Delay Timer (IRDT) expires. Once the IRDT time
expires the unit will transition to the "Loop Stabilization"
state and turn the solution pump "On" (if pump mode is in
"Auto"). Once the loop stabilization timer has expired, the
unit will transition into the ice building mode and will run
fully loaded until the IBTS is reached. After the IBTS is
reached, the unit will transition into the "Ice Rebuild De-
lay" mode again. The unit will continue to cycle through
the ice building, ice rebuild delay and loop stabilization
states until the unit is cycled out of the ice building mode
or the continuous ice building mode is changed to the
one time ice building mode.
o F greater than the LSC.
o F above the LSC, the unit