Carrier AquaEdge 19XR Series Start-Up, Operation And Maintenance Instructions Manual page 35

CALC REF DELTA TSAT + ENVELOPE LINE OFFSET surge
prevention will occur.
If ACTUAL GUIDE VANE POSITION is less than 30%, then in-
crease SURGE DELTA TSMIN in steps of 2ºF (1.2ºC) until one
of the three conditions listed above no longer applies. Do not
change SURGE DELTA TSMAX.
If ACTUAL GUIDE VANE POSITION is greater than 60%, then
increase SURGE DELTA TSMAX in steps of 2ºF (1.2ºC) until
cooling capacity is reached or one of conditions listed above no
longer applies. Do not change SURGE/HGBP DELTA TSMIN.
If ACTUAL GUIDE VANE POSITION is more than 30% AND
less than 60%, then:
1. Increase SURGE DELTA TSMIN in steps of 2ºF (1.2ºC).
Alternatively if Pressure Ratio Method is used for surge
protection increase PR at Minimum Opening.
2. Increase SURGE DELTA TSMAX in steps of 2ºF (1.2ºC).
Alternatively if Pressure Ratio Method is used for surge
protection increase PR at Full Load Opening.
3. Repeat Steps 1 and 2 until one of the conditions listed
above no longer applies.
NOTE: DELTA TSMIN should seldom need to be increased more
than 10 degrees above the selection program value. Likewise,
DELTA TSMAX rarely requires more than a 2ºF (1.2ºC) increase.
If surge is encountered then the controls surge prevention algo-
rithm surge line is probably too optimistic or high. Note following
parameters from HMI at surge:
• EVAPORATOR REFRIGERANT TEMP
• EVAPORATOR PRESSURE
• CONDENSER REFRIG TEMP
• CONDENSER PRESSURE
• ACTUAL GUIDE VANE POSITION
• AVERAGE LINE CURRENT
40
35
30
25
20
15
10
5
0
0 10 20 30 40 50
GV_POS
Fig. 36 — Effect of SURGE DELTA TSMIN on
Surge Prevention
Tsmin=30
Tsmin=40
Tsmin=50
60 70 80 90 100 110
a19-1959
45
40
35
30
25
20
15
10
5
0
0 10 20 30 40
Fig. 37 — Effect of SURGE DELTA TSMAX on
Surge Prevention
60.00
55.00
50.00
45.00
40.00
35.00
30.00
25.00
20.00
15.00
10.00
5.00
0.00
0 10 20 30 40
Fig. 38 — Effect of SURGE LINE SHAPE FACTOR on
Surge Prevention
40
35
30
25
20
15
10
5
0
0 10 20 30 40
Fig. 39 — Effect of SURGE LINE SPEED FACTOR on
Surge Prevention
If ACTUAL GUIDE VANE POSITION is less than 30%, go to
Step 1. If ACTUAL GUIDE VANE POSITION is greater than
60%, then go to Step 3.
1. Do not change SURGE LINE SHAPE FACTOR from the
value selected by Chiller Builder (ECAT). Decrease
SURGE DELTA TSMIN or PR at Minimum Opening.
Monitor chiller for surge.
2. If ACTUAL GUIDE VANE POSITION is still less than
30% and Step 1 failed, increase the value of SURGE LINE
35
50 60 70 80 90 100 110
a19-1960
GV_POS
50 60 70 80 90 100 110
GV_POS
50 60 70 80 90 100 110
GV_POS
a19-1962
Tsmax=60
Tsmax=70
Tsmax=80
Shape factor
= -0.020
Shape factor
= -0.040
Shape factor
= -0.050
Speed Factor
=1.60
Speed Factor
=1.85
Speed Factor
=2.00