65
LC 07--26 Variable Frequency Drive (Danfoss VFD)
The indoor fan motor is controlled by a VFD. The supply fan VFD
is located in the supply fan section behind the access door. The
VFD varies the frequency of the AC voltage supplied to the indoor
fan. This allows the variation 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. Fig. 38 and Table 34 show the VFD
terminals and connections.
TERMINALS
61, 68, 69
TERMINALS
18, 19, 27, 29
TERMINALS
12, 20, 55
TERMINALS
U, V, W
TERMINALS
L1, L2, L3
C14334
Fig. 38 -- 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 are necessary.
The VFD used has soft start capabilities to slowly ramp up the
speeds, eliminating any high inrush of air volume during speed
changes. While the basic VFD retains all of its standard
capabilities, the LC unit uses only a limited portion of these
features to provide discrete output speeds to the motor. The VFD is
not equipped with a keypad. A keypad is available as an accessory
(P/N: CRDISKIT002A00) for field installation or expanded
service access to VFD parameter and troubleshooting tables.
Table 34 – VFD Connections
POINT DESCRIPTION TYPE OF I/O
TERMINAL
NUMBER
TERMINAL
NAME
LOW VOLTAGE INPUTS
Low Voltage Power
(jumped to 18 & 27)
24vdc 12 +24v
Discrete Inputs Common Ground 20 GND
Analog Inputs Common Ground 55 GND
Te rminal 18 Discrete Input
(jumped from 24v)
Switch Input 18 DIG IN
Not Used Switch Input 19 DIG IN
Te rminal 27 Discrete Input
(jumped from 24v)
Switch Input 27 DIG IN
Not Used Switch Input 29 DIG IN
LEN communication + LEN+ 68 P
LEN communication --- L E N --- 69 N
LEN Communication
Common
LEN C 61 COMM. GND
HIGH VOLTAGE
Vo l t a g e L e g f r o m C --- 1 1 Voltage Input L1 MAINS
Vo l t a g e L e g f r o m C --- 1 3 Voltage Input L2 MAINS
Voltage Leg from IFTB Voltage Input L3 MAINS
Vo l t a g e L e g t o I F M --- 3 Voltage Output U MOTOR
Vo l t a g e L e g t o I F M --- 2 Voltage Output V MOTOR
Vo l t a g e L e g t o I F M --- 1 Voltage Output W MOTOR
The VFD communicate to the MBB over the local equipment
network (LEN). The VFD speed is controlled directly by the
controller over the LEN. The VFD parameters required for the
VFD to communicate on the LEN are shown in Table 35. Table 36
shows VFD parameters that are hard-coded by the SystemVut
controller. The parameters listed in Table 37 have corresponding
SystemVu controller configurations (SETTINGS UNIT
CONFIGURATIONS INDOOR FAN IFD VFD
PARAMETERS). The factory sets these parameters per the motor
installed in the unit and these should not be adjusted in the field.
These are only provided for drive or motor replacement. These
parameters in Table 37 require the drive to be off or 0% to change
them.
EQUIPMENT DAMAGE HAZARD
Failure to follow this warning could result in equipment
damage.
The VFD motor parameters shown in Table 39 should never be
changed in the field unless authorized by Carrier Corporation.
Damage could occur to the motor or unit if these are set to
anything besides what is shown in the table. These are only
provided for drive or motor replacement or future adjustments.
!
WARNING
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