Carrier 040-420 Example 5 Using Return Water Temperature Reset, Keypad Display Comments, CRST2

Page 40

I. Maximum Reset Amount (CRST2) - allowable range 0” to 20” F (0” to 11” C). This is maximum amount leav- ing chilled water set point is to be increased.

2.Maximum Reset Reference (CREF2) - allowable range 0” to 20” F (0” to 11” C). This is the cooler temperature drop at which reset reaches its maximum value.

3.Minimum Reset Amount (CRSTl) - allowable range 0” to 20” F (0” to 1 I” C). This is minimum amount leav- ing chilled water set point is to be increased when reset is initiated.

4.Minimum Reset Reference (CREFl) - allowable range 0” to 20” F (0” to 11” C). This is the cooler temperature drop at which reset is at its minimum value. (Reset be- gins here .)

NOTE: Reset set points are not accessible unless the reset function is enabled first. This is done as a field configura- tion. Select one of the 3 choices for type of reset: Return Fluid Reset, External Temperature Reset, or 4-20 mA Ex- ternal Signal (with a loop isolator) Reset.

If dual set point control is enabled (see Field Wiring sec- tion on page 7 1), the amount of reset is applied to which- ever set point is in effect at the time.

Example 5 demonstrates how to activate reset. Example 6 demonstrates how to change the type of reset. Assume that reset is to be based on return water temperature, the desired reset range is to be 2” to 10” F (1” to 5.5” C) and full load is a 10” F (5.5” C) drop across the cooler. See Fig. 4.

Activating reset based on external temperature or 4-20 mA signal is done the same way, except the reference set point range is 20” to 125” F (-6.6” to 5 1.6” C), or 4 to 20 mA depending on which method was selected at the field configuration step.

Example 5 - Using Return Water

Temperature Reset

 

KEYPAD

DISPLAY

 

COMMENTS

 

ENTRY

RESPONSE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Field

configuration

 

 

 

FLD CFG

 

subfunction of

 

 

 

 

 

 

service

 

function

 

 

 

CSPTYP X

Scroll

past single/dual

 

 

CRTYP 0

 

Display shows no reset

 

 

 

type has been selected

 

 

 

 

 

 

 

CRTYP

1

 

Return water temperature

 

 

 

is selected and activated

 

 

 

 

 

 

 

SET POINT

System set points

 

 

 

CPSl 44.0

Present

occupied

chilled

 

 

water set point

 

 

 

 

 

 

 

 

 

CPSl 45 6

Enter

new chilled

water

 

 

set point

 

 

 

 

 

 

 

 

 

RESET

 

 

Reset set points

 

 

 

CRST2

0

0

F;li;g

 

maximum reset

 

 

0

 

 

 

 

 

CRST2

10

0

Cooling

maximum

reset

 

 

is 10 F

 

 

 

 

CREF2 0.0

Cooling

maximum

reset

 

 

reference is 0” F

 

 

 

 

 

 

 

 

 

CREF2 1.0

Cooling

maximum

reset

 

 

reference is 1 F

 

 

 

 

 

 

 

 

 

CRSTI

0 0

Cooling

minimum

reset

 

 

is 0” F

 

 

 

 

 

 

 

 

 

 

 

 

 

CRSTI 2.0

Cooling

minimum

reset

 

 

is 2 F

 

 

 

 

 

 

 

 

 

 

 

 

 

CREFl

0.0

Cooling

minimum

reset

 

 

reference is 0” F

 

 

 

 

 

 

 

 

 

CREFl

8 0

Cooling

minimum

reset

 

 

reference is 8 F

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

IO

9

8

7

f73c=) --/ 35.3

18

16

MIN RESET REFERENCE

(CREF I ) q 13

100

8 0

6 0

0

2

3

4

5

6

7

8

9

IO

RESET REFERENCE TEMPERATURE (COOLER EWT-LWT)

Fig. 4 - Cooling Return Water Reset

40

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Contents Contrc Unit Sizes and Modular Combinations Unit ModelKeypaddisplay Ground Fault Interrupter Source PSIRELAY, B FieldLOCAL/ENABLE-STOP-CCN Switch Positions and Operation Compressor Protection Control Module CpcsThermistor and Transducer Locations ThermistorsCapacity Control StepsLoading Sequence a Loading Sequence B Unit Control Steps060A\~**Hz Capacity Control Steps, 040-070 cantLoading Sequence a Loading Sequence B Unit Oy&ya Capacity Control Steps, 040-070 cantFBI 08Aqy,y AitiA4l&pi’ Steps BP’Loading Loading Sequence B Unit Control Altt Bitt Wtf2Z$’Altt Loading Sequence a Loading Equence B Unit’tt Amrox$-t&Z3 Loading Sequence a Quence B Unit Control Displacement Compressors UWrW Arwox A2.p $#l 110 50 HzAlt,Blv Loading Equence a Displacement Compressors MvroxEquence B Awrox Drt,t 130, 24OA130,24OA 130, 240AAttll’ Loading Equence a UnitT3g A2.pLoading Sequence a Sequence B Unit $$V LOAD11 Control Size StepsLoadin Sequence B Unit Displacement Compressors UVvW PWprox 8514wB2,B3 Al% Al’,BILoading Sequence B Unit Capacity Control Steps, 225, 250,280 30GT Displacement Compressors AwoxLoac \IG Sequence a Loading Sequence B Unit Loac Capacity Control Steps, 225, 250,280 cant30GT Capacity Control Steps, 225, 250, 280 cant 2501G Sequence a Loading Sequence B Unit ControlCondenser Fan Sequence FAN Arrangement FAN Numbers Contactor ControlledCondenser Fan Sequence cant FAN Arrangement FAN Numbers~jACToR 30GT250 60 HzKeypad and Display Module Also Called Hsio Keypad and Display Module UsageAccessing Functions and Subfunctions Functions and SubfunctionsFunctions Operation Keypad Display Description Entry ResponseKeypad Directory Keypad Directory cant Status cant Subfunction Keypadentry Display CommentPressure AnalogSubfunction Outputs Display Subfunction Keypad Entry Display Comment OutputsOutputs HgbraKeypad Directory cant Test cant Subfunction Keypad Entry Display Comment OverrideClock Select QzqKeypad Directory Schedule cant Keypad Directory cant Service cord Keypad Directory cant Example 1 Reading Alarm Codes Operationat and Mode Display CodesExample 2 Reading Current Operating Modes Local on Cool Alarms Modes Local on M O D EKeypad Display Example 4 Reading and Changing Chilled Water Set Point Example 3 Using Test FunctionKeypad Display Comments Entry Response Example 5 Using Return Water Temperature Reset Keypad Display CommentsCRST2 CrstiExample 6 Changing Reset Type Reset Reference Temperature Outdoor AIR 1OR Space TempEKE FLD CFG Ertyp Lstyp Demand Keypad Display Entry ResponsePpiq Demand Limiting Example 8 Setting Time of Day Day of WeekMAX Demand Kimax = Factory Configuration Keystrokes Adjustable Field ConfigurationsExample 9 Using the Schedule Function DisplayExample 9 Using the Schedule Function cant Example 10 Holiday Schedule FunctionTypical Stoppage Faults and Reset Types Complete Unit Stoppage Complete unit stopAlarm Codes Action Taken Probable Cause N T R O LPage Page ’ Sl R ’ STnanz Switch CGFCompressor Contactor Relay SNBFig. IOD 24-V Safety Circuit Wiring 225, 250, and 280 Units Electronil c Expansion Valve EXV Page Thermistor and Pressure Transducer Locations Suction Refrigerant Temperature Sensor T7, T8 040-210Associated Modular Units Pressure Transducer 2i.b Voltage Drop Voltage Resistance DropEqualizer OIL Pressure Suction Pressure Sight Glass Line Transducer Each CompressorControl Modules PSIO, SIO Address SelectorSensor Bus Wiring Communications Processor Module PsioComm Troubleshooting 1NO. of Accessory Standard and Accessory UnloadersCircuit Circuit B Or2 30GN190-210 3OGT225,250,280 Accessory Unloader Control Wiring 080-110 SO/SO Hz and 130 60 HzHgbpr TLNContactor Switch Circuit Breaker Transformer LmyTEF4Module STAGE2Module J7-15Thermistor ElJ7-16Installation Remote Dual Set Point ControlPage Page Copyright 1994 Carrier Corporation

040-420 specifications

The Carrier 040-420 is a highly regarded commercial HVAC unit specifically designed for efficient heating and cooling in medium- to large-sized buildings. Known for its reliability and advanced technology, this system is ideal for a variety of applications ranging from offices to industrial spaces.

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