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APPENDIX G — OPTIONAL GREENSPEED/LOW AMBIENT CONTROL (cont)
Configure Greenspeed/Low Ambient Control
The Greenspeed/low ambient control is configured for propor-
tional integral (PI) control mode. The VFDs control varies the
condenser fan motor speed to maintain a setpoint of discharg-
ing head pressure.
The following
Comfort
Link control configurations must be set
when using a Greenspeed/low ambient device:
•
Configuration
COOL
OV.EN
= YES
Test Greenspeed/Low Ambient Control
To test the control and motor in the test mode, run compressor
no. 1. The Greenspeed/low ambient electronic control adjusts
the fan speed based on the discharge line pressure input. En-
sure that fans are rotating clockwise (as viewed from above). If
rotation is backward, lock out all power then swap 2 leads AF-
TER the VFDs control.
For A series units, fan stages react to discharge pressure trans-
ducers (DPT) (
Pressures
REF.P
DP.A
and
DP.B
) which
are connected to the compressor discharge piping in circuit A
and B. The control converts the pressures to the corresponding
saturated condensing temperatures (
Temperatures
REF.T
SCT.A
and
SCT.B
).
Unit size (
Configuration
UNIT
SIZE
), refrigerant type
(
Configuration
UNIT
RFG.T
), and condenser heat ex-
changer type (
Configuration
UNIT
CND.T
) are used to
determine if the second stage fans are configured to respond to
a particular refrigerant circuit (independent control) or both re-
frigerant circuits (common control). The 48/50A060 units with
microchannel (MCHX) condenser heat exchangers are the only
units that utilize independent fan controls.
There are configurations provided for head pressure and low
ambient control that can be found at the local display under
Configuration
COOL
.
Greenspeed/Low Ambient (OV)
[OUTDOOR_VFD] The condenser fan staging control for the
unit will be managed directly by the
Comfort
Link controls
through the use of VFDs. There will be no VFDs installed in
the standard unit. This configuration must be set to YES if the
optional condenser fan VFDs are installed on the unit. Setting
this configuration to YES alters the condenser fan staging se-
quence to accommodate the Greenspeed/low ambient control
algorithm.
The standard unit is capable of mechanical cooling operation
down to 32°F outdoor temperature. With the addition of optional
Greenspeed/low ambient speed control on the stage 1 condenser
fans, mechanical cooling operation down to –20°F outdoor tem-
perature is possible.
This configuration will have a range of NO/YES and will de-
fault to NO.
Head Pressure Setpoint (HPSP)
[HPSP] This is the head pressure setpoint used by the
Com-
fort
Link control during condenser fan, head pressure control.
This configuration will have a range of 80 to 150°F and a de-
fault of 100°F.
Compressor Lockout Temperature (MC.LO)
[OATLCOMP] This configuration defines the outdoor air tem-
perature below which mechanical cooling is locked out. To
make proper use of Motormaster control, it will be necessary
for an operator to manually change this setting. This configura-
tion will have a range of –20 to 55°F and a default of 40°F.
Fig. T — Greenspeed/Low Ambient VFD Control Location — 48/50A060 Units
Summary of Contents for WEATHERMAKER 48A2020
Page 112: ...112 Fig 20 Typical Main Control Box Wiring Schematic 48 50A Units ...
Page 113: ...113 Fig 21 Typical Auxiliary Control Box Wiring Schematic ...
Page 114: ...114 Fig 22 Typical 2 Stage Gas Heat Wiring Schematic Size 060 Units Shown ...
Page 115: ...115 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown TO NEXT PAGE ...
Page 116: ...116 Fig 23 Typical Staged Gas Heat Wiring Schematic Size 060 Units Shown cont ...
Page 117: ...117 Fig 24 Typical Electric Heat Control Schematic 50 Series Size 060 Units Shown ...
Page 118: ...118 Fig 25 Typical Controls Option Wiring Schematic SW1 SW2 OR DEHUMIDIFY SWITCH ...
Page 119: ...119 Fig 26 Typical Power Schematic 48 50A2 A3 A4 A5 060 Unit Shown ...
Page 120: ...120 Fig 27 Typical Power Schematic of Greenspeed Low Ambient Option 48 50A 060 Unit Shown ...
Page 121: ...121 Fig 28 Typical Small Chassis Component Location Size 020 035 Units ...
Page 122: ...122 Fig 29 Typical Large Chassis Component Locations Size 040 060 Units ...
Page 185: ...185 APPENDIX C VFD INFORMATION cont Fig F Internal Enclosure Fan Replacement A48 7716 ...