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SERVICE
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution will result in equipment damage.
DO NOT exceed the recommended minimum Hz or cfm
settings. Operating these units at a Hz setting below 40 Hz or
at a cfm below the minimums listed in Tables 2-10 (page 4)
will result in damage to the unit.
Figures 6-23 show the location of the VFD option in the various
units covered by this document.
SAV™ Option Components
The SAV factory option is comprised of three major components
and related connecting harnesses:
1.
Fan Speed Relay Board
2.
Variable Frequency Drive
3.
Indoor Fan Motor, designed for use with VFD
Fan Speed Relay Board
This board (Part Number: HK50ZA002) is designated as the VFD
Fan Board on the unit wiring diagram labels. It is a small (3.0 x
3.12 in., 76 x 79 mm) printed circuit board with four SPDT con-
trol relays. See Fig. 26. There is no software on this board. The
relay board is located in the unit's main control box; refer to unit
label diagram for Component Location view.
Fig. 26 — VFD Fan Board
The board is arranged in two separate circuits with individual pin
connectors. Connector J1 is connected to the 24-vac input signal
circuit with the four relay coils. Connector J2 is connected to the
24-VDC output circuit that connects to the VFD's terminal strip.
See Fig. 28 (on page 19) for a simplified connection schematic for
Fan Speed Relay board and the VFD.
In this SAV application, there are three inputs to the relay board,
originating from the space thermostat's G, Y2 and W1 terminals.
An input from terminal G (for continuous fan operation for venti-
lation or from a Y1 call) will result in the VFD starting the indoor
fan motor and running the motor at LOW speed. An input from ei-
ther Y2 or W1 will result in the VFD running the indoor fan motor
at HIGH speed. See Table 11 for relay operation for each unit
mode. Relay K4 is not used in this 2-speed application.
Table 11 — Two-Speed Configuration Logic
(Thermostat Control)
RELAY COIL STATUS CONTROLLING
INPUT
K1
K2
G
Off
Off
Y1
Off
Off
Y2
Off
On
W1
On
On
Configuration Jumpers
The relay board has two configuration jumpers, marked JW1
and JW2. For this 2-speed motor application, both jumpers
must be cut and open (see Fig. 27). Factory-installed boards
will have these jumpers cut. Service replacement boards have
these jumpers intact; servicer must cut both jumpers when in-
stalling a new service board. Failure to cut these jumpers will
cause continuous fan motor operation.
Fig. 27 — Jumpers JW1 and JW2 Cut for
Two-Speed Fan Board Configuration
Variable Frequency Drive
The VFD switches the indoor fan motor speed between full/high
speed (60 Hz motor operation) and reduced/low speed (40 Hz
motor operation) as required by ASHRAE 90.1-2016 and
IECC-2015 requirements for two-stage HVAC units. The VFD
is factory-configured to match the current and power require-
ments 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, the
SAV 2-speed application uses only a limited portion of these fea-
tures to provide two discrete output speeds to the motor. Conse-
quently the VFD is not equipped with a keypad. A keypad is avail-
able as an accessory (Part Number: CRDISKIT001A00)
ACH550/ACS320
or
ACH580 for field-installation or expanded service access to VFD
parameter and troubleshooting tables.
CONFIGURATION OVERRIDE HAZARD
Do not use ABB or Carrier start-up assistant on this VFD
application. Use of start-up assistant will override the factory
VFD configurations.
The SAV control circuit inputs to the VFD are 24-VDC signals.
•
For ACS320 VFDs the voltage is sourced from the VFD at
its terminal 9 (+24 V). SAV speed inputs are received at
terminals 13 (DI-2) for low speed (40 Hz) motor operation
and 14 (DI-3) for high speed (60 Hz) motor operation. See
Table 12 and Fig. 29 (on page 20).
18
FAN MOTOR
OUTPUT
SPEED
K3
On
K3
Low (40 Hz)
On
K3
Low (40 Hz)
On
K2
High (60 Hz)
On
K1
High (60 Hz)
Cut Jumper JW2
- as shown
Cut Jumper JW1
- as shown
(Part
Number: CRDISKIT003A00)
CAUTION
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