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then Lo Cool Mode mechanical stages = 2 and Hi Cool
Mode mechanical stages = 2.
5. If the economizer position is greater than
Configuration
ECON
EC.MX
– 5% for more than 8 minutes but
less than 11.5 minutes and mechanical cooling has started
then:
Lo Cool Mode mechanical stages = 2
Hi Cool Mode mechanical stages = 3
6. If the economizer position is greater than
Configuration
ECON
EC.MX
– 5% for more than 11.5 minutes and
mechanical cooling has started then:
Lo Cool Mode mechanical stages = 2
Hi Cool Mode mechanical stages = 3 (for 020 to 027
units only)
Hi Cool Mode mechanical stages = 4 (for 030 to 060
units only)
NOTE: If some compressors are not available due to being
faulted, the Hi Cool Mode number of compressors are affected
before the Lo Cool Mode number of compressors. For exam-
ple, if a 4 compressor unit has one compressor faulted, and the
economizer is not active, then an HVAC mode Hi Cool
requested number of compressors is changed from 4 to 3. If
another compressor faults, then both Lo Cool and Hi Cool
requested number of compressors are set to 2. In addition,
compressors cannot be brought on faster than one every
30 seconds. If the control needs to bring on 2 compressors at
once, the first compressor will come on followed by the second
compressor 30 seconds later.
Staging of compressors is shown in Tables 49-60.
EDT Low Override
— There is an override if EDT drops too
low based on an alert limit that will lock out cooling. If the
supply air/evaporator discharge temperature (EDT) falls below
the alert limit (
Configuration
ALLM
SA.L.O
) cooling will
be inhibited. There is a 20-minute hold off on starting cooling
again once the following statement is true: EDT minus (
Run
Status
COOL
SUMZ
ADD.R
) has risen above
SA.L.O
.
The variable
ADD.R
is one of the SumZ cooling algorithm
control variables dedicated mainly for multi-stage control.
2-Stage Control and the Economizer
— The 2-stage logic will
first check for the availability of the economizer. If free cooling
can be used, then the control will first attempt to use the free
cooling.
If no mechanical cooling is active, and the economizer is
active, the economizer will first attempt to control to a cooling
control point of either the supply air set point high (
SA.HI
) or
supply air set point low (
SA.LO
) plus any reset applied,
depending on whether High Cool or Low Cool mode is in ef-
fect, respectively.
If one stage of mechanical cooling is on, and the economiz-
er is active, then the economizer will attempt to control to 53 F.
Also If HVAC mode = LOW COOL, the second stage of
mechanical cooling will be locked out.
If the set point cannot be satisfied or the economizer is not
active, then cooling will be brought on one stage at a time
when the evaporator discharge temperature (EDT) is greater
the 1.5° F above the current cooling control point. A start-up
time delay of 10 minutes and steady state delay after a com-
pressor is energized of 5 minutes is enforced.
If both circuits of mechanical cooling are running, then the
economizer will attempt to control to 48 F. If the economizer is
active and the outside-air temperature (OAT) is less than the
cooling control point + 0.5 F, the compressors will be locked
off. When mechanical cooling is on, the control may also use
the economizer to trim the leaving-air temperature to prevent
unnecessary cycles of the compressor stages.
See the Economizer Integration with Mechanical Cooling
section on page 50 for more information on the holding off of
mechanical cooling as well as the economizer control point.
Table 49 — 2-Stage Sequence —
48/50AJ,AW020-027
Table 50 — 2-Stage Sequence —
48/50AJ,AW030-060
Table 51 — Staging Sequence without Hot Gas Bypass —
48/50AK,AY020-027 and Multi-Stage 48/50AJ,AW020-027
STAGE
SEQUENCE 1
SEQUENCE 2
0
1
2
0
1
2
Thermostat Inputs
Thermostat Inputs
Y1
OPEN CLOSED CLOSED OPEN CLOSED CLOSED
Y2
OPEN
OPEN
CLOSED OPEN
OPEN
CLOSED
COMP
Compressor Status
Compressor Status
A1
OFF
ON
ON
OFF
OFF
ON
A2
OFF
OFF
ON
OFF
ON
ON
B1
OFF
OFF
ON
OFF
OFF
ON
UNIT
Unit Capacity
Unit Capacity
020
0%
33%
100%
0%
33%
100%
025
0%
30%
100%
0%
30%
100%
027
0%
33%
100%
0%
33%
100%
STAGE
SEQUENCE 1
SEQUENCE 2
0
1
2
0
1
2
Thermostat Inputs
Thermostat Inputs
Y1
OPEN CLOSED CLOSED OPEN CLOSED CLOSED
Y2
OPEN
OPEN
CLOSED OPEN
OPEN
CLOSED
COMP
Compressor Status
Compressor Status
A1
OFF
ON
ON
OFF
ON
ON
A2
OFF
ON
ON
OFF
ON
ON
B1
OFF
OFF
ON
OFF
OFF
ON
B2
OFF
OFF
ON
OFF
OFF
ON
UNIT
Unit Capacity
Unit Capacity
030
0%
45%
100%
0%
45%
100%
035,036
0%
48%
100%
0%
48%
100%
040,041
0%
43%
100%
0%
43%
100%
050
0%
45%
100%
0%
45%
100%
051,060
0%
50%
100%
0%
50%
100%
STAGE
SEQUENCE 1
SEQUENCE 2
0
1
2
3
4
0
1
2
3
4
COMP
Compressor Status
Compressor Status
A1
OFF
ON
ON
OFF
ON
OFF
OFF
ON
ON
ON
A2
OFF
OFF
ON
ON
ON
OFF
ON
ON
OFF
ON
B1
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
ON
ON
UNIT
Unit Capacity 48/50A
Unit Capacity 48/50A
020
0%
33%
67%
67%
100%
0%
33%
67%
67%
100%
025
0%
30%
65%
70%
100%
0%
35%
65%
65%
100%
027
0%
33%
67%
67%
100%
0%
33%
67%
67%
100%
Содержание WEATHERMAKER 48/50AJ
Страница 103: ...103 Fig 15 Typical Main Control Box Wiring Schematic 48 50AJ AK AW AY Units cont a48 8355 ...
Страница 104: ...104 Fig 16 Typical Main Control Box Wiring Schematic 48 50A2 A3 A4 A5 Units a48 8355 ...
Страница 105: ...105 TO NEXT PAGE Fig 17 Typical Auxiliary Control Box Wiring Schematic A48 7294 ...
Страница 106: ...106 Fig 17 Typical Auxiliary Control Box Wiring Schematic cont a48 8356 ...
Страница 107: ...107 Fig 18 Typical 2 Stage Gas Heat Wiring Schematic Size 051 and 060 Units Shown a48 8357 ...
Страница 108: ...108 TO NEXT PAGE Fig 19 Typical Staged Gas Heat Wiring Schematic Size 051 and 060 Units Shown A48 7296 ...
Страница 109: ...109 Fig 19 Typical Staged Gas Heat Wiring Schematic Size 051 and 060 Units Shown cont A48 8358 ...
Страница 110: ...110 Fig 20 Typical Electric Heat Control Schematic 50 Series Size 051 and 060 Units Shown a50 8228 ...
Страница 111: ...111 TO NEXT PAGE Fig 21 Typical Power Schematic 48 50AJ AK AW AY051 and 060 Units Shown A48 7298 ...
Страница 112: ...112 FROM PREVIOUS PAGE Fig 21 Typical Power Schematic 48 50AJ AK AW AY051 and 060 Units Shown cont a48 8360 ...
Страница 113: ...113 Fig 22 Typical Power Schematic 48 50A2 A3 A4 A5060 Unit Shown ...
Страница 114: ...114 SW1 SW2 OR DEHUMIDIFY SWITCH Fig 23 Typical Controls Option Wiring Schematic a48 8361 ...
Страница 115: ...115 Fig 24 Typical Small Chassis Component Location Size 020 035 Units a48 8362 ...
Страница 116: ...116 Fig 25 Typical Large Chassis Component Locations Size 036 060 Units A48 7302 ...
Страница 169: ...169 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716 ...