Carrier 30MP - Setpoint Adjustments; OA Reset Functionality; RH Cooling Reset

Sequence of Operation
30MP Multi-chiller CARRIER CORPORATION ©2018
Installation and Start-up Guide All rights reserved
24
OA reset
You can raise the water temperature setpoint as a function of the outdoor air temperature. If you set
Cooling
Setpoint OA Reset
to
Enable
, then as the OA temperature drops below the
OAT CHW Supply Reset High Limit
, the
water temperature setpoint increases proportionally between
OAT CHW Supply Reset High Limit
and
OAT CHW
Supply Reset Low Limit
. At
OAT CHW Supply Reset Low Limit
, the maximum reset amount,
Maximum OA CHW
Reset
, is added to the configured water temperature setpoint.
If
Cooling Setpoint OA Reset
is set to
Disable
, then the configured water temperature setpoint is used.
RH cooling reset
The 30MP Multi-chiller can reduce any calculated OA reset, if the sensed relative humidity is above the control
setpoint. If you set
RH Cooling Setpoint Reset
to
Enable
, as the RH increases above the
Occ Relative Humidity
Setpoint
, a PID calculates the amount of reduction in the OA reset value.
RH Cooling Setpoint Reset
is only
applicable if the OA reset is active, since it can only reduce what is calculated by that algorithm.
RH Cooling
Setpoint Reset
will NOT lower the water temperature setpoint below the user-defined
Chilled Water Setpoint
value.
If you set
RH Cooling Setpoint Reset
to
Disable
, then the configured
Chilled Water Setpoint
, plus any calculated
OA reset, is the controlling setpoint.
Power failure recovery
The controller has a
Power Fail Restart Delay
after a power loss. You can configure the amount of time in
seconds, up to 600. When the power returns, the controller prevents operating and starting any chillers for that
amount of time.
The controller can also immediately restart the prior number of operating chillers in their previous capacity, if the
duration of a power outage was less than the configured
Immediate Restart Time
in minutes. The plant returns to
capacity quickly if there is a short outage and prevents waiting to load the plant at the ACR rate. This feature adds
stages every 30 seconds until the previously operating plant capacity is reached.
Cool enable
The controller can prevent chiller operation if the OAT is below an adjustable OA temperature. If
Cool Enable
is set
to
Enable
and there is a valid OA temperature and if the OA temperature is greater than the
Cooling Lockout
Temperature
, the controller actively controls the chillers as required. If the OA temperature falls below the
configured lockout value minus 2°, then all chillers are disabled.