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Table 18 — Compressor Stage and Circuit Cycling, Example 3
LEGEND
NOTES:
1. Total Cap. (Total Unit Capacity) and Cir. Cap. (Circuit Capacity)
are approximate percentage values.
2. Example is to determine minimum load control, staged circuit
loading, and automatic circuit select.
Table 19 — Compressor Stage and Circuit Cycling, Example 4
LEGEND
NOTES:
1. Total Cap. (Total Unit Capacity) and Cir. Cap. (Circuit Capacity)
are approximate percentage values.
2. Example is to determine minimum load control, staged circuit
loading, and automatic circuit select.
The capacity control algorithm runs every 30 seconds. The
algorithm attempts to maintain the Control Point at the desired
set point. Each time it runs, the control reads the entering and
leaving fluid temperatures. The control determines the rate at
which conditions are changing and calculates 2 variables based
on these conditions. Next, a capacity ratio (SM2) is calculated
using the 2 variables to determine whether or not to make any
changes to the current stages of capacity. This ratio value
ranges from –100 to +100%. If the next stage of capacity is a
compressor, the control starts (stops) a compressor when the
ratio r100% (–100%). If the next stage of capacity
is the Minimum Load Control, the control energizes (deener-
gizes) the Minimum Load Control when the ratio reaches
+60% (–60%). If installed, the minimum load valve solenoid
will be energized with the first stage of capacity. The control
will also use the minimum load valve solenoid as the last stage
of capacity before turning off the last compressor. If the close
control feature (
Configuration
UNIT
HGBP
=
2
) is en-
abled the control will use the minimum load valve solenoid
whenever possible to fine tune leaving fluid temperature con-
trol. A delay of 90 seconds occurs after each capacity step
change with Minimum Load Control. A delay of 3 minutes oc-
curs after each compressor capacity step change.
BRINE CHILLER OPERATION — For chiller sizes 120 to
390 with the factory-installed brine option, discharge and liq-
uid line solenoids are added to all circuits (Circuit B only for
size 120). The control system must be correctly configured for
proper operation. The minimum load valve option must be en-
abled (
Configuration
UNIT
HGBP
=1
) and the fluid type
must be set to medium temperature brine (
Configuration
SERV
FLUD
=2
). The discharge and liquid line solenoid
valves are wired in parallel so they will both open and close at
the same time. The main function of the solenoid valves is to
isolate a portion of the condenser section when only a single
compressor is running to allow for proper oil return to the com-
pressors. A chart showing solenoid operation is shown below:
CAPACITY CONTROL OVERRIDES — The following ca-
pacity control overrides (
Run Status
VIEW
CAP.S
) will
modify the normal operation routine. If any of the following
override conditions listed below is satisfied, it will determine the
capacity change instead of the normal control.
Override #1: Cooler Freeze Protection — This override at-
tempts to avoid the freeze protection alarm. If the Leaving
Water Temperature is less than Brine Freeze Set Point
STAGE
TOTAL
CAP.
CIRCUIT A
CIRCUIT B
CIRCUIT C
Cir. Cap.
MLC
A1
A2
A3
Cir. Cap.
MLC
B1
B2
B3
Cir. Cap.
MLC
C1
C2
C3
0
0
0
0
0
1
8
0
X
24
X
X
0
2
11
0
33
X
0
3
22
33
X
33
X
0
4
33
33
X
33
X
33
X
5
44
33
X
66
X
X
33
X
6
55
66
X
X
66
X
X
33
X
7
66
66
X
X
66
X
X
66
X
X
8
77
66
X
X
100
X
X
X
66
X
X
9
88
100
X
X
X
100
X
X
X
66
X
X
10
100
100
X
X
X
100
X
X
X
100
X
X
X
MLC —
Minimum Load Control
STAGE
TOTAL
CAP.
CIRCUIT A
CIRCUIT B
CIRCUIT C
Cir. Cap.
MLC
A1
A2
A3
Cir. Cap.
MLC
B1
B2
B3
Cir. Cap.
MLC
C1
C2
C3
0
0
0
0
0
1
8
0
0
24
X
X
2
11
0
0
33
X
3
22
0
0
66
X
X
4
33
0
0
100
X
X
X
5
44
33
X
0
100
X
X
X
6
55
66
X
X
0
100
X
X
X
7
66
100
X
X
X
0
100
X
X
X
8
77
100
X
X
X
33
X
100
X
X
X
9
88
100
X
X
X
66
X
X
100
X
X
X
10
100
100
X
X
X
100
X
X
X
100
X
X
X
MLC —
Minimum Load Control
CIRCUIT CAPACITY
DISCHARGE/LIQUID SOLENOID
VALVE OPERATION
All compressors off
Solenoids energized
One compressor starting
Solenoids deenergized after
30-second delay
Two or more compressors
running
Solenoids energized
Reduction from two to one
compressor running
Solenoids deenergized with no
delay
Summary of Contents for AQUASNAP 30RBA315
Page 77: ...77 Fig 37 Control Schematic 30RB060 080 a30 4619...
Page 78: ...78 Fig 38 Control Schematic 30RB090 150 a30 4620...
Page 79: ...79 Fig 39 Control Schematic 30RB160 190 a30 4622...
Page 80: ...80 Fig 40 Control Schematic 30RB210 300 a30 4622...
Page 81: ...81 Fig 41 Heat Reclaim Control Schematic a30 4622...