Carrier 19XL specifications Load Surge Prevention Occurs TOO Soon Occurs TOO Late

MODIFY CONTROLLER IDENTIFICATION IF NECES- SARY Ð The controller identi®cation screen is used to change the PSIO module address. Change this address for each chiller if there is more than one chiller at the jobsite. Write the new address on the PSIO module for future reference.

Change the LID address if there is more than one chiller on the jobsite. Access the LID con®guration screen to view or modify this address.

INPUT EQUIPMENT SERVICE PARAMETERS IF NEC- ESSARY Ð The Equipment Service table has three service tables: Service1, Service2, and Service3.

Con®gure SERVICE1 Table Ð Access Service1 table to modify/view the following to jobsite parameters:

Chilled Medium	Water or Brine?
Brine Refrigerant Trippoint	Usually 3° F (1.7° C) below
	design refrigerant temperature
Surge Limiting or Hot Gas	Is HGBP installed?
Bypass (HGBP) Option
Minimum Load Points	Per job data Ð
(T1/P1)	See Modify Load Points section
Maximum Load Points	Per job data Ð
(T2/P2)	See Modify Load Points section
Amps Correction Factor	See Table 6
Motor Rated Load Amps	Per job data
Motor Rated Line Voltage	Per job data
Motor Rated Line kW	Per job data
	(if kW meter installed)
Line Frequency	50 or 60 Hz
Compressor Starter Type	Reduced voltage or full?

NOTE: Other values are left at the default values. These may be changed by the operator as required. Service2 and Service3 tables can be modi- ®ed by the owner/operator as required.

Modify Minimum and Maximum Load Points (DT1/P1;

DT2/P2) If Necessary ÐThese pairs of chiller load points, located on the Service1 table, determine when to limit guide vane travel or to open the hot gas bypass valve when surge prevention is needed. These points should be set based on individual chiller operating conditions.

If, after con®guring a value for these points, surge pre- vention is operating too soon or too late for conditions, these parameters should be changed by the operator.

Example of con®guration: Chiller operating parameters

Refrigerant used: HCFC-22

Estimated Minimum Load Conditions:

44 F (6.7 C) LCW

45.5 F (7.5 C) ECW

43 F (6.1 C) Suction Temperature

70 F (21.1 C) Condensing Temperature

Estimated Maximum Load Conditions:

44 F (6.7 C) LCW

54 F (12.2 C) ECW

42 F (5.6 C) Suction Temperature

98 F (36.7 C) Condensing Temperature

Calculate Maximum Load Ð To calculate maximum load points, use design load condition data. If the chiller full load cooler temperature difference is more than 15° F (8.3 C),

estimate the refrigerant suction and condensing tempera- tures at this difference. Use the proper saturated pressure and temperature for the particular refrigerant used.

Suction Temperature:

42 F (5.6 C) = 71.5 psig (521 kPa) saturated refrigerant pressure (HCFC-22)

Condensing Temperature:

98 F (36.7 C) = 190 psig (1310 kPa) saturated refrigerant pressure (HCFC-22)

Maximum Load DT2:

54 ± 44 = 10° F (12.2 ± 6.7 = 5.5° C)

Maximum Load DP2:

190 ± 71.5 = 118.5 psid (1310 ± 521 = 789 kPad)

To avoid unnecessary surge prevention, add about 10 psid

(70 kPad) to DP2 from these conditions:

DT2 = 10° F (5.5° C)

DP2 = 130 psid (900 kPad)

Calculate Minimum Load Ð To calculate minimum load con- ditions, estimate the temperature difference that the cooler will have at 10% load, then estimate what the suction and condensing temperatures will be at this point. Use the proper saturated pressure and temperature for the particular refrig- erant used.

Suction Temperature:

43 F (6.1 C) = 73 psig (503 kPa) saturated refrigerant pressure (HCFC-22)

Condensing Temperature:

70 F (21.1 C) = 121 psig (834 kPa) saturated refrigerant pressure (HCFC-22)

Minimum Load DT1:

45.5 ± 44 = 1.5° F (7.5 ± 6.7 = 0.8° C)

Minimum Load DP1:

121 ± 73 = 45 psid (834 ± 503 = 331 kPad)

Again, to avoid unnecessary surge prevention, add 10 psid

(70 kPad) at DP1 from these conditions: DT1 = 1.5 F (0.8 C)

DP1 = 60 psid (410 kPad)

If surge prevention occurs too soon or too late:

LOAD	SURGE PREVENTION	SURGE PREVENTION
	OCCURS TOO SOON	OCCURS TOO LATE
At low	Increase P1 by	Decrease P1 by
loads
	10 psid (70 kPad)	10 psid (70 kPad)
(,50%)
At high	Increase P2 by	Decrease P2 by
loads
	10 psid (70 kPad)	10 psid (70 kPad)
(.50%)

Modify Amp Correction Factors Ð To modify the amp cor- rection factor, use the values listed in Table 6. Enter the appropriate amp correction factor in the Service1 table of Equipment Service.

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