144
APPENDIX C — VFD INFORMATION
On variable air volume units with optional VFD, the supply
fan speed is controlled by a 3-phase VFD. The VFD is located
in the supply fan section behind a removable panel. The VFD
speed is controlled directly by the
Comfort
Link™ controls
through a 4 to 20 mA signal based on a supply duct pressure
sensor. The VFD has a display, which can be used for service
diagnostics, but setup of the building pressure and control loop
factors should be done through the Scrolling Marquee display.
The VFD is powered during normal operation to prevent
condensation from forming on the boards during the off mode
and is stopped by driving the speed to 0 (by sending a 4 mA
signal to the VFD).
The A series units use ABB VFDs. The interface wiring for
the VFDs is shown in Fig. A. The VFD connects through
an isolation board to the 4 to 20 mA RCB board. Terminal
designations are shown in Table A. Configurations are shown
in Table B.
Table A — VFD Terminal Designations
TERMINAL
FUNCTION
U1
V1
W1
Three-Phase Main Circuit Input Power Supply
U2
V2
Three-Phase AC Output to Motor, 0 V to
W2
Maximum Input Voltage Level
X1-11 (GND)
X1-12 (COMMON)
Factory-supplied jumper
X1-10 (24 VDC)
X1-13 (DI-1)
Run (factory-supplied jumper)
X1-10 (24 VDC)
Start Enable 1 (Factory-supplied jumper). When
X1-16 (DI-4)
opened the drive goes to emergency stop.
X1-2 (AI-1)
X1-3 (AGND)
Factory wired for 4 to 20 mA remote input
Fig. A — VFD Wiring
A48-7712
Summary of Contents for WEATHERMAKER 48AJ020
Page 95: ...95 Fig 13 Typical Main Control Box Wiring Schematic A48 7787 ...
Page 96: ...96 TO NEXT PAGE Fig 14 Auxiliary Control Box Wiring Schematic A48 7294 ...
Page 98: ...98 Fig 15 Typical 2 Stage Gas Heat Wiring Schematic Size 051 and 060 Units Shown A48 6866 ...
Page 102: ...102 TO NEXT PAGE Fig 18 Typical Power Schematic Size 051 and 060 Units Shown A48 7298 ...
Page 104: ...104 Fig 19 Controls Option Wiring Schematic A48 7810 ...
Page 105: ...105 Fig 20 Small Chassis Component Location Size 020 035 Units A48 7301 ...
Page 106: ...106 Fig 21 Large Chassis Component Locations Size 036 060 Units A48 7302 ...