Carrier 30GTN Installation Instructions Manual page 8

Temperature Reset (4 to 20 mA) —
plied and generated, externally powered 4 to 20 mA signal can
be used to provide leaving fluid temperature reset. The signal
must be connected to TB6. Connect the signal to TB6-2/5
(positive/negative). This is a simple linear function which re-
quires only two configuration changes. Follow the steps out-
lined in Table 2 to enable the function and configure the reset
temperature at 10º F for the 20 mA signal.
MODE KEYPAD
(RED LED) ENTRY
CONFIGURATION
ENTER
A field sup-
Table 2 — Menu Configuration of Temperature Reset Mode
KEYPAD
SUBMODE
ENTRY
DISP
UNIT
OPT1
OPT2
RSET
ENTER
ENTER
ENTER
ENTER
ESCAPE
ENTER
ENTER
ENTER
ESCAPE
The configuration is now complete. As an example, if the
cooling set point (CSP.1) is set to 44 F, the control will linearly
reset the control point (CTPT) based on the 4 to 20 mA signal.
There will be no reset for a 4 mA signal. If the reset signal was
20 mA, the CTPT would be changed to 54 F. Similarly, a
12 mA reset signal would reset CTPT to 49 F. The actual 4 to
20 mA reset signal seen by the control can be viewed by ac-
cessing the item RSET, located under the Inputs mode, sub-
mode 4-20.
ITEM DISPLAY ITEM EXPANSION
COOLING
CRST 0
RESET TYPE
0
0
1
1
COOLING
CRST 1
RESET TYPE
CRT1 125
CRT2 0
DEGREES
DGRC 0
COOL RESET
0
0
10
10
DGRC 10
8
COMMENTS
SCROLLING STOPS
FLASHING '0'
SELECT '1'
CHANGE ACCEPTED
ITEM/VALUE/UNITS
SCROLLING RETURNS
SET MAXIMUM
RESET AMOUNT
FOR 20 mA SIGNAL
SCROLLING STOPS
FLASHING '0'
SELECT '10'
CHANGE ACCEPTED
ITEM/VALUE/UNITS
SCROLLING RETURNS