132
JOHNSON CONTROLS
5276178-JIM-C-0118
Sequence of Operation
Return Air Based SAT Reset
When the
“SAT RESET METHOD”
is set to
“RETURN
AIR”
, the controller monitors the
“RETURN AIR
TEMP”
and sets the
“SUPPLY AIR TEMP ACTIVE
SP”
to a value between the
“SAT HIGH SETPOINT”
and the “
SAT LOW SETPOINT”
. If the
“RETURN AIR
TEMP”
is equal to or greater than the
“RAT SETPOINT
FOR LOW SAT”
, the
“SUPPLY AIR TEMP ACTIVE
SP”
shall be the
“SAT LOW SETPOINT”
. If the
“RETURN AIR TEMP”
is equal to or less than the
“RAT
SETPOINT FOR HIGH SAT”
, the
“SUPPLY AIR TEMP
ACTIVE SP”
shall be the
“SAT HIGH SETPOINT”
.
When the
“RETURN AIR TEMP”
is between the
“RAT
SETPOINT FOR HIGH SAT”
and the
“RAT SETPOINT
FOR LOW SAT”
the
“SUPPLY AIR TEMP ACTIVE
SP”
shall be linearly interpolated between the
“SAT
HIGH SETPOINT”
and the
“SAT LOW SETPOINT”
(see Figure 63).
Supply Fan Speed Based SAT Reset
When the
“SAT RESET METHOD”
is set to
“SUPPLY
FAN SPEED”
, the Unit Controller will monitor the
“SUPPLY FAN VFD SPEED”
command and set the
“SUPPLY AIR TEMP ACTIVE SP”
to a value between
the
“SAT HIGH SETPOINT”
and the
“SAT LOW
SETPOINT”.
If the
“SUPPLY FAN VFD SPEED”
is
equal to or greater than the
“FAN SPEED SETP FOR
LOW SAT”
, the
“SUPPLY AIR TEMP ACTIVE SP”
shall be the
“SAT LOW SETPOINT”.
If the
“SUPPLY
FAN VFD SPEED”
is equal to or less than the “
FAN
SPEED SETP FOR HIGH SAT”
, the
“SUPPLY
AIR TEMP ACTIVE SP”
shall be the
“SAT HIGH
SETPOINT”
. When the
“SUPPLY FAN VFD SPEED”
is between the
“FAN SPEED SETP FOR LOW SAT”
and the
“FAN SPEED SETP FOR HIGH SAT”
, the
“SUPPLY AIR TEMP ACTIVE SP”
shall be linearly
interpolated between the
“SAT HIGH SETPOINT”
and
the
“SAT LOW SETPOINT”(see Figure 64).
(Default = 55.0 °F)
(Default = 65.0
°
F)
Return Air Temp
(RAT)
Active SAT
Set Point
Increasing RAT
SAT LOW SETPOINT
SAT HIGH SETPOINT
RAT SETPOINT
FOR HIGH SAT
RAT SETPOINT
FOR LOW SAT
(Default = 55.0 °F)
(Default = 65.0
°
F)
Supply Fan Speed
%
Active SAT
Set Point
Increasing Supply Fan Speed
SAT LOW SETPOINT
SAT HIGH SETPOINT
FAN SPEED
FOR HIGH SAT
FAN SPEED
FOR LOW SAT
LD10307A
FIGURE 68 - ACTIVE SAT SET POINT VS. RETURN AIR TEMP
LD10308A
FIGURE 69 - ACTIVE SAT SET POINT VS. SUPPLY FAN SPEED
Содержание 40 25 TON
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