Carrier 30GTN - Page 9

9
Demand Limit (4 to 20 mA) —
A field-supplied 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 TB6-1/5 (positive/
negative). This is a simple linear function which requires only
two configuration changes. Follow the steps outlined in Table 3
to enable the function and configure a demand limit of 60% for
the 20 mA signal.
The configuration is now complete. There will be no de-
mand limit for a 4 mA signal. If the signal was 20 mA, the
chiller capacity (CAP) would be limited to 60%. Similarly, a
12 mA demand limit signal would limit chiller capacity to
80%. The actual 4 to 20 mA demand limit signal seen by the
control can be viewed by accessing the item DMND, located
under the Inputs mode, submode 4-20.
Table 3 — Menu Configuration of Demand Limit Mode
MODE
(RED LED)
KEYPAD
ENTRY
SUBMODE
KEYPAD
ENTRY
ITEM DISPLAY ITEM EXPANSION COMMENTS
CONFIGURATION
DISP
UNIT
OPT1
OPT2
RSET CRST 0
CRT1 125
CRT2 0
DGRC 0
DMDC 0
DEMAND LIMIT
SELECT
0
SCROLLING
STOPS
0 FLASHING ‘0’
2 SELECT ‘2’
2
CHANGE
ACCEPTED
DMDC 2
DEMAND LIMIT
SELECT
ITEM/VALUE/UNITS
SCROLLING RETURNS
DM20 100
DEMAND LIMIT AT
20 MA
100
SCROLLING
STOPS
100 FLASHING ‘100’
60 SELECT ‘60’
60
CHANGE
ACCEPTED
DM20 60
DEMAND LIMIT AT
20 MA
ITEM/VALUE/UNITS
SCROLLING RETURNS
ENTER
ENTER
ENTER
ENTER
ENTER
ESCAPE
ENTER
ENTER
ENTER
ESCAPE