Carrier AquaEdge 19XRV series Operation, Maintenance And Installation Manual page 76

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 50
GV_POS
Fig. 43 — Effect of SURGE LINE SHAPE FACTOR
on Surge Prevention
40
35
30
25
20
15
10
5
0
0 10 20 30 40 50
GV_POS
Fig. 44 — Effect of SURGE LINE SPEED FACTOR
on Surge Prevention
Fine Tuning VPF Surge Prevention — Figures 41-44 show
how the parameters defined below will affect the configured
surge line.
NOTE: Before tuning surge prevention check for VFD speed
limitation or capacity overrides. If the source of low capacity is
found in one of these places, do not proceed with an attempt to
tune the Surge Prevention configurations.
If capacity is not reached
and
1. ACTUAL GUIDE VANE POSITION < GUIDE VANE
TRAVEL RANGE
and
2. SURGE PREVENTION ACTIVE = YES
and
3. PERCENT LINE CURRENT < 100%
then the surge line is probably too conservative.
Note the following parameters from ICVC when maximum
AVERAGE LINE CURRENT achieved:
• EVAPORATOR REFRIGERANT TEMP
• EVAPORATOR PRESSURE
• CONDENSER REFRIG TEMP
• CONDENSER PRESSURE
Shape factor
= -0.020
Shape factor
= -0.040
Shape factor
= -0.050
60 70 80 90 100 110
a19-1961
Speed Factor
=1.60
Speed Factor
=1.85
Speed Factor
=2.00
60 70 80 90 100 110
a19-1962
• ACTUAL GUIDE VANE POSITION
• AVERAGE LINE CURRENT
The ACTIVE DELTA Tsat and the SURGE LINE DELTA
TSAT can be monitored on the VPF_STAT screen. When DEL-
TA TSAT exceeds SURGE LINE DELTA TSAT surge preven-
tion will occur.
If ACTUAL GUIDE VANE POSITION is less than 30%,
then increase SURGE/HGBP DELTA TSMIN in steps of 2º F
until one of the three conditions listed above no longer applies.
Do not change SURGE/HGBP DELTA TSMAX.
If ACTUAL GUIDE VANE POSITION is greater than
60%, then increase SURGE/HGBP DELTA TSMAX in steps of
2º F until cooling capacity is reached or one of conditions listed
above no longer applies. Do not change SURGE/HGBP DEL-
TA TSMIN.
If ACTUAL GUIDE VANE POSITION is more than 30%
AND less than 60%, then:
1. Increase SURGE/HGBP DELTA TSMIN in steps of 2º F.
2. Increase SURGE/HGBP DELTA TSMAX in steps of
F.
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. Like-
wise, DELTA TSMAX rarely requires more than a 2 degree
increase.
If surge is encountered then the surge line is probably too
optimistic or high. Note following parameters from ICVC at
surge:
• EVAPORATOR REFRIGERANT TEMP
• EVAPORATOR PRESSURE
• CONDENSER REFRIG TEMP
• CONDENSER PRESSURE
• ACTUAL GUIDE VANE POSITION
• AVERAGE LINE CURRENT
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/HGBP DELTA TSMIN in 1° F steps up to 5
times. Monitor chiller for surge.
2. If ACTUAL GUIDE VANE POSITION is still less than
30 and step 1 failed, then increase the value of SURGE
LINE SHAPE FACTOR in steps of 0.01 up to 2 times. For
example, if surge is encountered when shape factor is –
0.06, increase the SURGE LINE SHAPE FACTOR to –
0.05. If this does not solve the problem, go to Step 5, even
if ACTUAL GUIDE VANE POSITION is less than 30%.
3. Do not change SURGE LINE SHAPE FACTOR from the
value selected by Chiller Builder (ECAT). Decrease
SURGE/HGBP DELTA TSMAX by 1°F Steps up to 5
times. Monitor chiller for surge.
4. If ACTUAL GUIDE VANE POSITION is greater than
60% and Step 3 failed to eliminate surge, then set
SURGE/HGBP DELTA TSMAX to 5° F below the value
specified by Chiller Builder (ECAT). Increase the value
of the SURGE LINE SHAPE FACTOR in steps of 0.01 up
to 2 times. For example, if surge is encountered when the
SURGE LINE SHAPE FACTOR is –0.06, increase the
SURGE LINE SHAPE FACTOR to –0.05. If this does not
solve the problem, go to Step 5, even if ACTUAL
GUIDE VANE POSITION is greater than 60%.
5. If ACTUAL GUIDE VANE POSITION is greater than
30% but less than 60% or if Step 2 failed (with ACTU-
AL GUIDE VANE POSITION less than 30) or if Step
4 failed (with ACTUAL GUIDE VANE POSITION
76
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