Carrier 48/50AJ specifications 123, Terminal Function

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	A48-7709

Fig. 31 — VFD Wiring

Table 121 — 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

POWER EXHAUST — The units can be equipped with an optional power exhaust system. The power exhaust fans are forward-curved fans with direct-drive motors. The motors are controlled directly by the ComfortLink™ controls through the ECB1 board. On the 48/50A020-050 units there are 4 fans. On the 48/50A051 and 060 units there are 6 fans. The fan sequenc- es are controlled to provide 4 stages on the 48/50A020-050 units and 6 stages on the 48/50A051 and 060 units. There are two control methods. For CV applications the fans can be configured for 2 stages based on adjustable economizer damper positions. For VAV applications and CV units with the building pressure control option, the fans are sequenced to maintain a building pressure set point based on a building pressure transducer.

ECONOMIZER MOTOR — The economizer outside air and return air dampers are gear-driven dampers without linkage. A digitally controlled economizer motor controls their position. The motor position is controlled by the ECB1 board by means of a digital two-way communication signal. This allows for

accurate control of the motors as well as feedback information and diagnostics information. The control has a self-calibration routine that allows the motor position to be configured at initial unit start-up. The motor is located on the economizer and can be reached through the filter access door.

THERMISTORS AND PRESSURE TRANSDUCERS — The 48/50AJ,AK,AW,AY units are equipped with thermistors and pressure transducers. These units have two thermistors connected to the condenser coil and two pressure transducers that are connected to the low side of the system.

The 48/50A2,A3,A4,A5 units are equipped with four pres- sure transducers. These units have two pressure transducers connected to the low side of the system and two pressure trans- ducers connected to the high side of the system.

By using either temperature sensors or transducers, the ComfortLink controller displays the high and low side pres- sures and saturation temperatures. A normal gage set is not required.

SMOKE DETECTOR — The units can be equipped with an optional smoke detector located in the return air. The detector is wired to the ComfortLink controls and, if activated, will stop the unit by means of a special fire mode. The smoke detector can also be wired to an external alarm system through TB5 terminals 10 and 11. The sensor is located in the return air sec- tion behind the filter access door.

FILTER STATUS SWITCH — The units can be equipped with an optional filter status switch. The switch measures the pressure drop across the filters and closes when an adjustable pressure set point is exceeded. The sensor is located in the return air section behind the filter access door.

RETURN AIR CO2 SENSOR — The unit can also be equipped with a return air IAQ CO2 sensor that is used for the demand control ventilation. The sensor is located in the return air section and can be accessed from the filter access door.

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