Specifications

45
Table 34 — Capacity Control Overrides
Override #22: Minimum On Time Delay
— In addition to
Override #13 Minimum On/Off and Off/On Time Delay, for
compressor capacity changes, an additional 90-second delay
will be added to Override #13 delay. No compressor will be
deenergized until 3 minutes have elapsed since the last com-
pressor has been turned ON. When this override is active, the
capacity control algorithm calculations will be performed, but
no capacity reduction will be made until the timer has expired.
A control with higher precedence will override the Minimum
On Time Delay.
Override #23: Circuit A Low Saturated Suction Tempera-
ture in Cooling
Override #24: Circuit B Low Saturated Suction Tempera-
ture in Cooling — If the circuit is operating close to the opera-
tional limit of the compressor, the circuit capacity will remain at
the same point or unload to raise the saturated suction tempera-
ture. This algorithm will be active if at least 1 compressor in the
circuit is on and one of the following conditions is true:
1. Saturated Suction Temperature is less than the Brine
Freeze Setpoint (Brine Freeze Setpoint, LOSP) –6º F
(3.3º C).
2. Saturated Suction Temperature is less than the Brine
Freeze Setpoint (Brine Freeze Setpoint, LOSP) and the
circuit approach (Leaving Water Temperature – Saturated
Suction Temperature) is greater than 15º F (8.3º C) and
the Circuit Superheat (Discharge Gas Temperature – Sat-
urated Discharge Temperature) is greater than 25º F
(13.9º C).
NOTE: The freeze set point is 34 F (1.1 C) for fresh
water systems (Cooler Fluid Type, FLUD=1). The
freeze set point is Brine Freeze Set Point (Brine Freeze
Setpoint, LOSP), for Medium Temperature Brine
systems (Cooler Fluid Type, FLUD=2).
If any of these conditions are met, the appropriate operating
mode, 21 (Circuit A) or 22 (Circuit B) will be in effect.
Override #34: Circuit A Low Refrigerant Charge
Override #35: Circuit B Low Refrigerant Charge — The ca-
pacity override attempts to protect the compressor from start-
ing with no refrigerant in the circuit. This algorithm runs only
when the circuit is not operational (compressors is OFF). There
are several criteria that will enable this override:
1. The saturated suction temperature or saturated discharge
temperature is less than –13 F (–25 C).
2. Both of these conditions must be true:
a. The saturated suction temperature or saturated
discharge temperature is less than leaving fluid
temperature by more than 5.4º F (3.0º C).
b. Saturated suction temperature or saturated dis-
charge temperature is less than 41 F (5 C).
3. All of these conditions must be true:
a. The saturated suction temperature or saturated
discharge temperature is less than leaving fluid
temperature by more than 5.4º F (3.0º C).
b. Saturated suction temperature or saturated dis-
charge temperature is less than 41 F (5 C).
c. Saturated suction temperature or saturated dis-
charge temperature is less than the brine freeze
point (Brine Freeze Setpoint, LOSP) by more
than 6º F (3.3º C).
NOTE: The freeze set point is 34 F (1.1 C)
for fresh water systems (Brine Freeze Setpoint,
FLUD=1). The freeze set point is brine freeze set
point (Brine Freeze Setpoint, LOSP), for medium
temperature brine systems (Cooler Fluid Type,
FLUD=2).
4. Both of these conditions must be true:
a. The saturated suction temperature or saturated
discharge temperature is less than leaving fluid
temperature by more than 5.4º F (3.0º C).
CAPACITY CONTROL OVERRIDES
1 Cooler Freeze Protection
2 Circuit A Low Saturated Suction Temperature in Cooling
3 Circuit B Low Saturated Suction Temperature in Cooling
4 —
5 Low Temperature cooling and High Temperature Heating (LWT)
6 Low Temperature cooling and High Temperature Heating (EWT)
7 Ramp Loading
8 Service Manual Test Override
9 Demand Limit
10 Cooler Interlock Override
11 High Temperature Cooling and Low Temperature Heating
12 High Temperature Cooling and Low Temperature Heating
(minimum load control in effect)
13 Minimum On/Off and Off/On Time Delay
14 Slow Change Override
15 System Manager Capacity Control
16 Circuit A High Pressure Override
17 Circuit B High Pressure Override
18 —
19 Standby Mode
20 —
21 —
22 Minimum On Time Delay
23 Circuit A Low Saturated Suction Temperature in Cooling
24 Circuit B Low Saturated Suction Temperature in Cooling
25 —
26 —
27 —
28 —
29 —
30 —
31 —
32 —
33 —
34 Circuit A Low Refrigerant Charge
35 Circuit B Low Refrigerant Charge
36 —
37 —
38 —
39 —
40 —
41 Circuit A High Current Override
42 Circuit B High Current Override
43 —
44 Circuit A High Suction Superheat at Part Load
45 Circuit B High Suction Superheat at Part Load
46 —
47 —
48 —
49 —
50
—
51 —
52 —
53 Circuit A Delay for Unloading the Slide Valve
54 Circuit B Delay for Unloading the Slide Valve
55 —
56 —
57 —
58 —
59 Circuit A Low Oil Level
60 Circuit B Low Oil Level
61 —
62 Circuit A High Motor Temperature Override
63 Circuit B High Motor Temperature Override
64 —
65 —
66 Circuit A High Discharge Gas Override
67 Circuit B High Discharge Gas Override
69 Water-Cooled Heating Mode Low Entering Water Temperature
70 Water-Cooled Max Condenser LWT = 133 F (45 C)
71 Wait Until Pump Turns On Override
77 Boostload Function Active
80 Circuit A, 81 Circuit B: Long Time Minload Run