22
Table 19 — Start/Stop Control
LEGEND
All of the control type and unit state combinations listed in
Table 19 will determine the actual unit running state. In addi-
tion, when under remote type control, unit Start/Stop actions
will be determined by both On/Off and Occupied/Unoccupied
status if the changeover option is enabled. If the changeover
option is not enabled, only the On/Off switch will be used to
command the unit to Start or Stop.
NOTE: When changing from one control method (Local,
Remote, or CCN) to another, the unit will observe a transition
through the Off state before being allowed to start again. At
this time the on-to-off delay is always applied.
MACHINE START DELAY — An option to delay the start
of the machine is available. This parameter is useful in keeping
multiple machines from starting at the same time in case of a
power failure. The parameter has a factory default of 1 minute.
This parameter also has a role in the timing for a chilled water
flow switch alarm. To configure this option with the Touch Pi-
lot display, select Main Menu Configuration Menu Gen-
eral Configuration and select Unit Off to On Delay.
FAST LOADING — The Fast Capacity Recovery function
allows for an accelerated unit start-up. This is especially useful
following brief power outages at data centers where rapid re-
start can keep data center operating. This should not be used on
normal comfort cooling applications. To activate the Fast Ca-
pacity Recovery, go to Main Menu Configuration Menu
Service Parameters and set Fast Capacity Recovery. The avail-
able options are as follows:
• 0 (Normal Loading Sequence): Follows the set delays for
unit and circuit start up
• 1 (Quick Start Loading): Ignores Capacity Override #53
(ON/OFF Delay)
• 2 (Fast Capacity Recovery): Removes the unit start-up
delay, ignores Capacity Override #53 (ON/OFF Delay),
and allows both compressors to start at the same time
(with a 10-second delay between starts)
Chilled Water Set Point Configuration — The
chilled water set point and fluid type configuration will deter-
mine the chiller operating conditions.
FLUID SET POINT CONTROL LOCATION — The fac-
tory default for the chilled water fluid set point is to control
to the leaving water temperature. An option to configure the
machine for entering water control is available. To config-
ure this option go to Main Menu Configuration Menu
Service Parameters. The default for Entering Fluid Control
is No (leaving fluid control is the default condition).
COOLING SET POINT SELECTION — The control point
represents the water temperature that the unit must produce.
The unit will vary the capacity depending on the unit load
operating conditions in order to satisfy the set point. The con-
trol point (CTRL_PNT) is calculated based on the active set
point and the reset calculation, where Control Point = Active
Setpoint + Reset. (See the section Temperature Reset on
page 33 for more information about Reset.) The forced value
can be used instead of any other set point calculation only
when Network is selected as the operating type for the unit (go
to Main Menu General Parameters to verify operating type).
DEFINING SET POINTS — The cooling set points are set
via the Setpoint Table (Main Menu Setpoint Table). Cooling
Setpoint 1 and Cooling Setpoint 2 are the temperatures that are
selectable as the Active Set Points for the unit operation. These
temperatures will be limited by the type of fluid in the system
(see Table 20).
In addition to the Cooling set points, users can also select
the Cooling Ice Setpoint and Cooling Ramp Loading from this
menu. See the Ice Storage Operation section on page 40 for
more details about the Cooling Ice Setpoint. Ramp Loading
limits the rate at which the unit will change cooling water tem-
perature (default is 1º F/min [0.6º C/min]).
All default set points are based on Leaving Water Control
(Entering Fluid Control, EWTO set to No). Values must be
confirmed for the individual set points. Limits for the set points
ACTIVE OPERATING TYPE
PARAMETER STATUS
CONTROL
METHOD
UNIT
STATUS
CHIL_S_S Onoff_sw ms-ctrl chil_occ state EMSTOP
Alarm
Shutdown
Local Off (LOFF) — — — — — — Local Off
Local On (L-C) — — — — Disable No Local On
Local Schedule (L-SC)
— — — Occupied Disable No Local On
— — — Unoccupied — — Local Off
Remote (rEM)
— Open — — — — Remote Off
— — — Unoccupied — — Remote Off
Closed Occupied — — Remote On
CCN
Disable — — — — — CCN Off
— — — Unoccupied — — CCN Off
Enable — — Occupied Disabled No CCN On
Master (MA St)
— — Local Unoccupied — — Local Off
— Open Remote — — — Remote Off
— — Remote Unoccupied — — Remote Off
Disable — CCN — — — CCN Off
— — CCN Unoccupied — — CCN Off
— — Local Occupied Disable No Local On
— Closed Remote Occupied Disable No Remote On
Enable CCN Occupied Disable No CCN On
—————
Enable — — Off
—Yes— Off
chil_occ — Chiller Occupied State
CHIL_S_S — CCN Chiller Start/Stop Command
EMSTOP — Emergency Stop
L-C — Local Control Operating Type
L-SC — Local Schedule Operating Type
MA St — Master/Slave Operating Type
ms-ctrl — Master/Slave Control
Onoff_sw — Remote On/Off Switch
rEM — Remote Operating Type
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