Unit installation

54
Variable Frequency Drive (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. Fig. 21 and Table 21 show the
VFD terminals and connections.
TERMINALS
10 – 16
TERMINALS
28 – 31
U1 V1 W1 U2 V2 W2
POWER
LED
FAULT
LED
C12225
Fig. 21 -- Variable Frequency Drive (VFD) Terminals and
Connections -- unit shown 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 connections
are necessary. While the basic VFD retains all of its standard
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 (PNO CRDISKIT001A00) for
field—installation or expanded service access to VFD parameter
and troubleshooting tables. The VFD used has soft start capabilities
to slowly ramp up the speeds, eliminating any high inrush of air
volume during speed changes.
Table 21 – VFD Connections
POINT DESCRIPTION TYPE OF I/O
TERMINAL
NUMBER
TERMINAL
NAME
LOW VOLTAGE INPUTS
Low Voltage Power
(jumped to DI1 & DI4)
24vdc 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
Vo l t a g e L e g f r o m C --- 1 1 Voltage Input U1 MAINS
Vo l t a g e L e g f r o m C --- 1 3 Voltage Input V1 MAINS
Voltage Leg from IFTB V oltage Input W1 MAINS
Vo l t a g e L e g t o I F M --- 3 Voltage Output U2 MOTOR
Vo l t a g e L e g t o I F M --- 2 Voltage Output V2 MOTOR
Vo l t a g e L e g t o I F M --- 1 Voltage Output W2 MOTOR
EQUIPMENT DAMAGE/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 desired
on these applications.
CAUTION
!
The VFDs communicate to the ComfortLink MBB over the local
equipment network (LEN). The VFD speed is controlled directly
by the ComfortLink controls over the LEN. The VFD parameters
required to allow the VFD to communicate on the LEN are shown
in Table 22. These are factory set and would only need to be
adjusted if replacing the drive. Table 23 shows VFD parameters
that are set by the ComfortLink controls, and sent to the VFD over
the LEN at power up of the VFD. These are hard-coded to be set as
listed. The parameters listed in Table 24 have corresponding
ComfortLink configurations (Configuration →I.FAN → S.VFD).
The factory sets these parameters per motor installed in the unit and
these should not be adjusted in the field. These are only provided
for drive or motor replacement or future adjustments. These
parameters in Table 24 require the drive to be off or 0% to change
them. Table 25 lists the status information the VFD sends to the
ComfortLink controls. This table is updated at every scan the
ComfortLink controls perform of the LEN. This occurs
approximately once every second.
EQUIPMENT DAMAGE HAZARD
Failure to follow this warning could result in equipment
damage.
The VFD motor parameters shown in Table 26 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
48/50LC