
160
To connect the unit to the network:
1. Turn off power to the control box.
2. Cut the CCN wire and strip the ends of the red (+), white
(ground), and black (–) conductors. (Substitute appropriate
colors for different colored cables.)
3. Connect the red wire to (+) terminal on the COMM board,
the white wire to COM terminal on the COMM board, and
the black wire to the (-) terminal on the COMM board.
4. The RJ14 CCN connector on the COMM board can also
be used, but is only intended for temporary connection (for
example, a laptop computer running Service Tool).
Restore power to unit.
Through the Navigator display, the user can access all the inputs
and outputs to check on their values and status. Because the unit is
equipped with suction pressure transducers and discharge satura
-
tion temperature sensors, the Navigator display can also display
pressures typically obtained from gages. The control includes a
full alarm history, which can be accessed from the display. In addi
-
tion, through the Navigator display the user can access a built-in
test routine that can be used at start-up commission and to diag
-
nose operational problems with the unit. The Navigator display is
located in the control box and is standard on all units.
SUPPLY FAN
The 48/50N units are equipped with a single air-foil type supply
fan. The units have an optional high and low fan that can be select
-
ed to match the airflow requirements of the application. Addition
-
ally, the motor horsepower size for the supply fan is also selected
to match the airflow requirements of the application. The fan sleds
are spring isolated and driven by a single 3-phase motor. The fan
is controlled directly by the
Comfort
Link controls.
VARIABLE FREQUENCY DRIVE (VFD)
Supply fans are powered and controlled with VFDs. The sup
-
ply fan VFD is located in the supply fan section behind an ac
-
cess door. Units equipped with optional power exhaust or re
-
turn fans will also be powered and controlled with a VFD. The
VFD for the power exhaust or return fan is located in the return
section behind an access door.
The N Series units use ABB VFDs. The VFDs communicate to
the
Comfort
Link MBB over the local equipment network (LEN).
The VFD speed is controlled directly by the
Comfort
Link controls
over the LEN. The interface wiring for the VFDs is shown in
Fig. 38 and the terminal designations are shown in Table 108. The
VFD has a keypad display panel that can be used for service diag
-
nostics and setting the initial VFD parameters required to allow
the VFD to communicate on the LEN. Additional VFD parame
-
ters are set by the
Comfort
Link controls, and sent to the VFD over
the LEN at power up of the VFD. The VFD faults can be reset
with the VFD keypad or through the
Comfort
Link controls
(
Alarms
R.CUR
=Yes).
Table 108 —
VFD Terminal Designations
POWER EXHAUST
The units can be equipped with an optional power exhaust sys
-
tem. The power exhaust fan is a belt-driven, forward-curved
fan. For modulating (CV or VAV) applications, the fan is con
-
trolled by the
Comfort
Link controls based on building pressure
sensed by the building pressure transducer. The fan speed is
modulated to maintain the building pressure set point.
RETURN FAN
The return fan power exhaust assembly consists of one belt-
drive plenum fan. The return fan is a belt-driven backward-
curved fan. The plenum fan pressurizes the plenum fan section
so that the air can either be discharged horizontally out the
back of the unit or discharged through the return air section of
the economizer.
ECONOMIZER MOTOR(S)
The economizer outside air and return air dampers are motor
actuator-driven through linkages. Communicating economizer
motors controls their position. The motor position is controlled
by the MBB through the communication bus. This allows for
accurate control of the motors as well as feedback information
and diagnostics information. The control has a self-calibration
routine that allows the motor position to be configured at initial
unit start-up. The motors are located on the economizer and
can be reached through the filter access door.
THERMISTORS AND PRESSURE TRANSDUCERS
The unit is equipped with several thermistors for measurement
of temperatures. The thermistors are summarized in Table 109.
The units have 2 pressure transducers that are connected to the
low side of the system. These 2 pressure transducers measure
the low side pressure and are used for low pressure protection
and coil freeze protection.
The units also have 2 pressure transducers that are connected to
the high side of the system. These 2 pressure transducers mea
-
sure the discharge pressure and are used to cycle the condenser
fans to maintain head pressure.
By using the high and low side pressure transducers, the
Com
-
fort
Link controls display the high and low side pressures and
saturation temperatures and a normal gage set is not required.
IMPORTANT: A shorted CCN bus cable will prevent some
routines from running and may prevent the unit from starting.
If abnormal conditions occur, unplug the connector. If condi
-
tions return to normal, check the CCN connector and cable.
Run new cable if necessary. A short in one section of the bus
can cause problems with all system elements on the bus.
TERMINAL
FUNCTION
U1
3-phase main circuit input power supply
V1
W1
U2
3-Phase AC Output to Motor, 0 V to
Maximum Input Voltage Level
V2
W2
X1-11 (GND)
Factory-supplied jumper
X1-12 (D-COM)
X1-10 (+24 V)
Factory-supplied jumper
X1-13 (DI-1)
X1-10 (+24 V)
Start Enable 1 (Factory-supplied jumper). When
opened the drive goes to emergency stop.
X1-16 (DI-4)
X1-28 (SCR)
Factory wired for local equipment network LEN
communication
X1-29 (B+)
X1-30 (B-)
X1-31 (AGND)
X1-32 (SCR)
Summary of Contents for WeatherExpert 48N2
Page 135: ...135 Fig 18 48 50N Typical Power Schematic Nominal 075 Ton Unit Shown ...
Page 136: ...136 Fig 19 48 50N Typical Power Schematic Nominal Ton 90 150 Units Shown ...
Page 137: ...137 Fig 20 48 50N Main Base Board Input Output Connections ...
Page 138: ...138 Fig 21 48 50N RXB EXB CEM Input Output Connections a48 9307 ...
Page 139: ...139 Fig 22 48 50N EXV SCB Input Output Connections a48 9308 ...
Page 140: ...140 Fig 23 48N Typical Modulating Gas Heat Unit Control Wiring ...
Page 141: ...141 Fig 24 50N Typical Electric Heat Unit Control Wiring ...
Page 144: ...144 Fig 27 48N Typical Gas Heat Section Wiring Nominal Ton 120 to 150 Units ...
Page 145: ...145 Fig 28 48 50N Typical Power Component Control Wiring 460 v ...
Page 146: ...146 Fig 29 48 50N Component Control Wiring 575 v Nominal Ton 075 to 150 Units ...
Page 147: ...147 Fig 30 48 50N Component Arrangement Power Box ...
Page 148: ...148 Fig 31 48 50N Component Arrangement Control Box ...
Page 240: ...240 APPENDIX D VFD INFORMATION CONT Fig G VFD Bypass Wiring Diagram WHEN USED ...