Carrier 48/50AJ specifications Appendix C VFD Information, Table a VFD Terminal Designations, 161

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 ComfortLink™ 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

A48-7712

Fig. A — VFD Wiring

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