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251
SECTION 30 - QUICK START
FORM 160.54-M1
ISSUE DATE: 10/25/2019
JOHNSON CONTROLS
JCI COMPANY CONFIDENTIAL
30
The following topics detail how the individual func-
tions are changed for Quick Restarts and Quick Nor-
mal Starts:
PRV Control
When Quick Start is enabled the PRV switch shall be
ignored and does not have to be closed in order to start.
When Quick Start is ENABLED the PRV position will
be held during coastdown and for 30 seconds after
coastdown. If a quick restart is not initiated, the PRV
control will return to standard during the not running
state.
When Quick Start is ENABLED during normal start-
ups, a continuous open signal will be sent to the PRV
as soon as the oil pump run signal is enabled during
pre-lube. This open signal will be sent to the PRV until
pre-lube is complete and then PRV control will return
to standard automatic.
When Quick Start is ENABLED during quick restarts,
when the VSD is given a run signal, a continuous
open signal will be sent to the PRV. The open signal
will be sent to the vanes until LCHLT falls below the
Quick Pulldown Setpoint Offset. Once this occurs,
vane control shall revert to standard automatic control.
Any kind of limiting (current, etc.) that would close
the vanes will cause the vane control to revert back to
standard automatic control and operate as it currently
does. The PRV control will also be returned to normal
if the Pulldown Override Time timer expires. This tim-
er shall begin counting when the run signal is enabled.
VSD Control
When Quick Start is ENABLED, the VSD shall be
sent a precharge command during coastdown and for
30 seconds after the end of coastdown.
Chilled Liquid Flow
Normal operation checks for chilled liquid flow begin-
ning 5 seconds before the end of pre-lube. When Quick
Start is ENABLED this check is done before restarting.
If chilled liquid flow is not present by 30 seconds after
the end of coastdown, the chiller will revert to standard
quick normal start logic.
Chilled Liquid Pump Control
Normal operation turns the chilled liquid pump off at
the end of coastdown. When Quick Start is ENABLED
the chilled liquid pump is kept on for 30 seconds after
coastdown is completed. If a quick restart is not initi-
ated within 30 seconds of the end of coastdown, the
pump is returned to normal control.
Condenser Level Control
When Quick Start is ENABLED the variable orifice
position will be held in its current position during
coastdown and for 30 seconds after the completion of
coastdown. If a quick restart does not occur within 30
seconds of the end of coastdown the variable orifice
control will revert to standard logic and open.
When Quick Start is ENABLED, if a quick restart does
not occur within 30 seconds of the end of coastdown,
set a QUICK PRESET TIMER to the programmed
level control preset time. Count this timer down to 0.
When the next normal quick start occurs, subtract the
quick preset timer's current value from the preset time
so the VO does not close too far and would essentially
return to the last position it had held.
For normal operation a condenser level setpoint ramp-
ing algorithm is employed if the preset timer is set to
zero or the chiller is running or if the preset timer is
not zero and the chiller has been running for longer
than 180 seconds. When Quick Start is ENABLED, for
quick restarts only, the preset timer is ignored (no pre-
set takes place) and the ramping algorithm is engaged
immediately upon achieving a run state. For quick nor-
mal starts, level control works as it does currently.
Oil Sump Control
When Quick Start is ENABLED the pressure offset
calibration (and the associated fault) is disabled for
quick restarts only. The offset calculation from the last
normal start shall be used. For a normal quick start the
calibration and fault shall be active during pre-lube per
the standard logic.
Normal operation checks for low oil pressure (greater
than 25psid) beginning 5 seconds before the end of pre-
lube. When Quick Start is ENABLED this check shall
begin before restarting If the chiller does not restart,
this check will still be done on the next normal quick
start using standard logic. If oil pressure is not present
by 30 seconds after the end of coastdown, the chiller
will revert to standard quick normal start logic but will
not fault on low oil pressure. This fault is currently only
active during pre-lube and run. It shall not cause a shut-
down during coastdown or while not running.