Daikin WGZ030DW Installation, Operation And Maintenance Manual page 53

conditions are met:
The stage up timer completes
The ECWT is > Stage #1 ON set point
Bypass valve position is > the Stage Up @ set point (only if
Valve/VFD Control set point = Valve Stage) Additional stages
can turn on (up to the number specified by the Tower Stages
set point) when above conditions are met for the next stage
plus the following condition: VFD Speed is > the Stage Up @
set point (only if Valve/VFD Control set point = VFD Stage OR
Valve SP/VFD Stage)
Down staging shall occur when the following conditions are
met:
The stage down timer completes
The ECWT is < Stage #X ON (Temp) set point – Stage
Differential (Temp) set point point Bypass valve position is <
the Stage Down @ set point (only if Valve/VFD Control set
point = Valve Stage)
VFD Speed is < the Stage Down @ set point (only if Valve/VFD
Control set point = VFD Stage OR Valve
SP/VFD Stage)
Each stage up or stage down event shall restart both the
stage up and stage down timers. Only one fan output shall be
switched at a time (except that all outputs switch OFF when the
condenser pump state equals OFF).
Water-cooled On
SET TOWER SPs (1)
Tower Control= None
Tower Stages = X
StageUP/DN=XXX/XXX%
When Tower Control is None the control of condenser water
temperature is not by the MicroTech II
controller and assumed to be furnished elsewhere.
Tower Stages is the number of tower fans to be staged by the
controller, choices are 0, 1, or 2. "0" indicates control will be
by a bypass valve or variable speed pump controlled by the
MicroTech II controller.
StageUP/DN imposes a time delay between fan stages when
turning on or turning off.
Water-cooled On
SET TOWER SPs (2)
Stage ON (Temp)°F
#1 #2
XXX XXX
Stage ON Temp is the entering condenser water temperature
(ECWT) that will turn on tower fan #1 and #2. Default settings
are 70°F and 75°F. Cold condenser water will improve unit
efficiency but too cold can cause erratic operation. Settings
below 60°F are not recommended.
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Water-cooled On
SET TOWER SPs (3)
StageDiff = XX.X°F
Stage Up Tmr=XX min
StageDn Tmr=XX min
StageDiff is the number of degrees below the Stage ON that
will turn off the tower fans. For example, if Stage ON #1 is
70°F and StageDiff is 5°F, tower fan #1 will stage off when the
ECWT drops to 65°F and stage the fan on when the ECWT
rises to 70°F. The same is true for fan #2.
Stage Up timer is the number of minutes that must elapse
between the condenser pump starting (it starts with the unit)
and fan #1 starting or the time between fan #1 starting and fan
#2 starting.
StageDown is the elapsed time between staging down the fan
motors.
Water-cooled = Y
SET TOWER SPs (4)
Valve/VFD Control=
ValveSP/VFDStage
Valve Type=NC to Twr
Valve/VFD Control settings are None, Valve Set point, Valve
Stage, VFD Stage, or ValveSP/VFDStage. Default is None
which results in no control of the tower from the MicroTech II
controller.
Valve Set point, the valve will control (bypass tower) to hold the
minimum temperature as established by the Set Tower SPs in
screen (5) below.
This mode is operational when the Valve/VFD Control set point
is set to Valve Set point OR Valve SP/VFD Stage. In this mode
the valve output is varied with a proportional-derivative (PD)
algorithm (with deadband) in order to maintain the controlled
parameter (CP) at the desired value. The output is always
limited between the Valve Control Range (Min) set point and
the Valve Control Range (Max) set point. A valve increment
shall be computed once every 5 seconds according to the
following equation. (Error Gain and Slope Gain are set in menu
screen #8.)
Increment = [(Error) * (Error Gain set point)] + [(Slope) * (Slope
Gain set point)]
Where: Error = ECWT – Valve Set point
Slope = (Present CP) – (Previous CP)
When the Error is > the Valve Deadband set point, the valve
position analog output (% of full scale) is updated according to
the following equation.
New %Position = Old %Position + Increment/10
Valve Stage, controls from the fan stage set point in use. It
is recommended that the Valve Set point method explained
above be used rather than this mode.
This mode is only operational when the Valve/VFD Control
53 IOM 1322-1 • WATER-COOLED SCROLL COMPRESSOR
Unit Controller