Keypad entry allows the operator to make the
following checks by using :
·LID display check. Proper display is 8.8.8.8.8.8.8.8.
·Operation of alarm relay.
·Operation of condenser fans.
·Operation of chilled ¯uid pump.
·Operation of liquid line solenoids.
·Operation of the hot gas bypass relays.
·Operation of EXVs. To drive EXV fully open, enter
(100% open). To drive EXV fully closed, en-
ter (0% open).
·Operation of each remote alarm.
·Operation of Motormaster signals.
Keypad entry accesses the compressor and compressor unloader operational tests.
During compressor operational tests, compressor starts and runs for 10 seconds. Compressor service valves must be open. Energize crankcase heaters 24 hours prior to performing compressor tests.
Since test function checks only certain outputs, it is good practice to also check all inputs and outputs accessible
through the status function. These are located at | , | |
, and | (see Table 9). If keypad is not used |
for 10 minutes, unit automatically leaves test function and resumes rotating display. See Example 3.
Example 3 Ð Using Test Function
KEYPAD | DISPLAY | COMMENTS |
| |
ENTRY | RESPONSE |
| ||
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| |||
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| ||
| COMP | Factory/®eld test of compressors | ||
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| subfunction of test function |
|
| CPA 1 | OFF | Circuit A, Compressor 1A test |
|
| CPA 1 | ON | Pressing ENTR starts the test: |
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|
|
| when the compressor should be running | |
|
|
| the display shows CPA1 on |
|
| CPA 1 | OFF | If the test is allowed to time out (10 sec- | |
|
|
| onds) the display will show CPA1 off | |
| CPA 2 | OFF | Pressing the down arrow key advances the | |
|
|
| system to Circuit A, compressor 2 test | |
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|
|
| |
NOTE: Once a compressor has been run using the | function, |
it is not allowed to run again for 30 seconds.
accesses the transducer calibration subfunction.
All transducers must be calibrated in order for the unit to operate. Refer to Pressure Transducers section on page 60 for calibration procedure.
HISTORY FUNCTION Ð Pressing and dis-
plays total unit run time, total run time for each circuit, and total run time for each compressor.
Pressing and displays total unit starts, the total starts for each circuit, and total starts for each com-
pressor. Pressing | and | displays the last 10 alarms |
along with a description of each alarm.
SET POINT FUNCTION Ð Set points are entered through the keypad. Set points can be changed within the upper and lower limits, which are ®xed. The ranges are listed below.
Chilled Fluid Set Point
Water:
38 to 86 F (3.3 to 30 C)
Medium Brine:
14 to 86 F (±10 to 30 C)
Pulldown Set Point
0.2 to 2.0 F (0.11 to 1.1 C)/min.
Reset Set Points
Maximum Reset Range:
±30° to 30° F (±17° to 17° C)
External Temperature Reset ±40 to 240 F (±40 to 118 C)
Chiller Fluid DT: 0° to 15° F (0° to 8° C)
External Signal Reset 4 to 20 mA
Demand Limit Set Points
Switch Input:
Step 1 Ð 0 to 100% Capacity Reduction
Step 2 Ð 0 to 100% Capacity Reduction
External Signal:
Maximum Demand Limit 4 to 20 mA
Minimum Demand Limit 4 to 20 mA
Loadshed Demand Delta: 0 to 60%
Maximum Loadshed Time: 0 to 120 min.
Set points are grouped in subfunctions as follows:
Subfunction displays chiller ¯uid set points.
a.The ®rst value shown is the occupied chilled ¯uid set point.
b.The next value displayed depends on how the sched- ule function has been programmed. (See pages 44- 47.) If dual set point has been selected, the next set
point after has been pressed is the second chilled ¯uid set point. If single set point or inactive sched-
ule | has been | selected in | the | schedule | function, |
then | when | is pressed, | the | display | shows the |
head pressure set points, one for each circuit. These are utilized only if the set point controlled method of
head pressure control is selected in .
c. The ®nal value displayed when the is pressed
is the cooling ramp loading rate. This is the maximum rate at which the leaving chilled ¯uid is allowed to drop, and can be ®eld set from 0.2 to 2.0 F (.11° to 1.1° C)/minute. This value is not displayed unless the function is enabled (see Adjustable Field Con®gura- tions on page 44).
Reading and Changing Set Points Ð Example 4 shows how to read and change the chilled ¯uid set point. Other set points can be changed by following the same procedure. Refer to Table 9 for the sequence of display of set points in each sub- function.
38