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Variable Frequency Drive (VFD)
VFDs are available as a factory-installed option for 48/50LC
series units. 04-06 units use ABB VFDs, while 07-26 units use
Danfoss VFDs. For details on 07-26 units with VFDs, see “48/
50LC 07-26 Variable Frequency Drive (Danfoss VFD)” on
page 77.
48/50LC 04-06 VARIABLE FREQUENCY DRIVE (ABB VFD)
On units equipped with supply fan VFDs, the indoor fan motor
is controlled by a 3-phase VFD. The supply fan VFD is located
in the supply fan section behind the access door. These units use
ABB VFDs. The VFD varies the frequency of the AC voltage
supplied to the indoor fan. This allows the variance in the speed
of the fan. The VFD is always powered during normal operation
and the fan is stopped by driving the speed to 0. Figure 41 and
Table 30 show the VFD terminals and connections.
Fig. 41 — 48/50LC 04-06 Variable Frequency Drive
(VFD) Terminals and Connections
(Unit shown with front cover removed)
The VFD is factory-configured to match the current and power
requirements for each motor selection and all wiring connections
are completed by the factory; no field adjustments or connec-
tions are necessary. While the basic VFD retains all of its stan-
dard capabilities, this application uses only a limited portion of
these features to provide discrete output speeds to the motor.
Consequently, the VFD is not equipped with a keypad. A keypad
is available as an accessory (P/N: CRDISKIT001A00) for field
installation or expanded service access to VFD parameter and
troubleshooting tables. The VFD has soft start capabilities to
slowly ramp up the speeds, eliminating any high inrush of air
volume during speed changes.
The VFDs communicate to the MBB over the local equipment
network (LEN). The VFD speed is controlled directly by the
SystemVu™ controller over the LEN. The VFD parameters re-
quired to allow the VFD to communicate on the LEN are
shown in Table 31. Table 32 shows VFD parameters that are
hard-coded by the SystemVu controller. The parameters listed
in Table 32 have corresponding SystemVu configurations
(SETTINGS UNIT CONFIGURATIONS INDOOR
FAN IFD VFD PARAMETERS). The factory sets these pa-
rameters per motor installed in the unit and these should not be
adjusted in the field. These are only provided for drive or mo-
tor replacement. These parameters in Table 32 require the drive
to be off or 0% to change them. See Tables 33 and 34 for VFD
parameters through the SystemVu controller.
TERMINALS
10 – 16
TERMINALS
28 – 31
U1 V1 W1 U2 V2 W2
POWER
LED
FAULT
LED
Table 30 — 48/50LC 04-06 VFD Connections
POINT
DESCRIPTION
TYPE OF I/O
TERMINAL
NUMBER
TERMINAL
NAME
Low Voltage Inputs
Low Voltage Power
(jumped to DI1 & DI4)
24 vdc 10 24v
Low Voltage Common
(jumped to DCOM)
Ground 11 GND
Discrete Inputs Common
(jumped from GND)
Ground 12 DCOM
Discrete Input 1
(jumped from 24v)
Switch Input 13 DI1
Not Used Switch Input 14 DI2
Not Used Switch Input 15 DI3
Discrete Input 4
(jumped from 24v)
Switch Input 16 DI4
Shielded Cable Ground Shield 28 SCR
LEN communication LEN 29 B+
LEN communication LEN 30 A–
LEN communication LEN 31 AGND
High Voltage
Voltage Leg from C-11 Voltage Input U1 MAINS
Voltage Leg from C-13 Voltage Input V1 MAINS
Voltage Leg from IFTB Voltage Input W1 MAINS
Voltage Leg to IFM-3 Voltage Output U2 MOTOR
Voltage Leg to IFM-2 Voltage Output V2 MOTOR
Voltage Leg to IFM-1 Voltage Output W2 MOTOR
CAUTION
EQUIPMENT DAMAGE AND PERFORMANCE
HAZARD
Failure to follow this caution may result in damage to the
unit or in degradation of unit performance.
Do not run the Carrier Assistant through the VFD keypad.
This will cause parameters to change value that are not de-
sired on these applications.
IMPORTANT: If the VFD appears to be communicating
(the VFD software version can be read in SERVICE
UNIT INFORMATION VERSIONS) but the loss of
communications fault persists, place the keypad in the Off
state. If communication is reestablished, the VFD had to be
in the Off state to save the configurations being sent. This
can occur after a VFD is replaced.
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