Carrier 48LC Series Controls, Start-up, Operation And Troubleshooting

Also see for 48LC 05: Controls, Start-Up, Operation and Troubleshooting Service and maintenance instructions Service and maintenance instructions

Contents

Carrier 48LC Series Controls, Start-up, Operation And Troubleshooting Manual pdf 65 page image

65LC 07--26 Variable Frequency Drive (Danfoss VFD)The indoor fan motor is controlled by a VFD. The supply fan VFDis located in the supply fan section behind the access door. TheVFD varies the frequency of the AC voltage supplied to the indoorfan. This allows the variation in the speed of the fan. The VFD isalways powered during normal operation and the fan is stopped bydriving the speed to 0. Fig. 38 and Table 34 show the VFDterminals and connections.TERMINALS61, 68, 69TERMINALS18, 19, 27, 29TERMINALS12, 20, 55TERMINALSU, V, WTERMINALSL1, L2, L3C14334Fig. 38 -- Variable Frequency Drive (VFD) Terminals andConnections -- unit shown with front cover removedThe VFD is factory–configured to match the current and powerrequirements for each motor selection and all wiring connectionsare completed by the factory; no field adjustments are necessary.The VFD used has soft start capabilities to slowly ramp up thespeeds, eliminating any high inrush of air volume during speedchanges. While the basic VFD retains all of its standardcapabilities, the LC unit uses only a limited portion of thesefeatures to provide discrete output speeds to the motor. The VFD isnot equipped with a keypad. A keypad is available as an accessory(P/N: CRDISKIT002A00) for field installation or expandedservice access to VFD parameter and troubleshooting tables.Table 34 – VFD ConnectionsPOINT DESCRIPTION TYPE OF I/O TERMINALNUMBERTERMINALNAMELOW VOLTAGE INPUTSLow Voltage Power(jumped to 18 & 27) 24vdc 12 +24vDiscrete Inputs Common Ground 20 GNDAnalog Inputs Common Ground 55 GNDTerminal 18 Discrete Input(jumped from 24v) Switch Input 18 DIG INNot Used Switch Input 19 DIG INTerminal 27 Discrete Input(jumped from 24v) Switch Input 27 DIG INNot Used Switch Input 29 DIG INLEN communication + LEN+ 68 PLEN communication --- LEN--- 69 NLEN CommunicationCommon LEN C 61 COMM. GNDHIGH VOLTAGEVoltage Leg from C--- 11 Voltage Input L1 MAINSVoltage Leg from C--- 13 Voltage Input L2 MAINSVoltage Leg from IFTB Voltage Input L3 MAINSVoltage Leg to IFM--- 3 Voltage Output U MOTORVoltage Leg to IFM--- 2 Voltage Output V MOTORVoltage Leg to IFM--- 1 Voltage Output W MOTORThe VFD communicate to the MBB over the local equipmentnetwork (LEN). The VFD speed is controlled directly by thecontroller over the LEN. The VFD parameters required for theVFD to communicate on the LEN are shown in Table 35. Table 36shows VFD parameters that are hard-coded by the SystemVutcontroller. The parameters listed in Table 37 have correspondingSystemVu controller configurations (SETTINGS  UNITCONFIGURATIONS  INDOOR FAN  IFD VFDPARAMETERS). The factory sets these parameters per the motorinstalled in the unit and these should not be adjusted in the field.These are only provided for drive or motor replacement. Theseparameters in Table 37 require the drive to be off or 0% to changethem.EQUIPMENT DAMAGE HAZARDFailure to follow this warning could result in equipmentdamage.The VFD motor parameters shown in Table 39 should never bechanged in the field unless authorized by Carrier Corporation.Damage could occur to the motor or unit if these are set toanything besides what is shown in the table. These are onlyprovided for drive or motor replacement or future adjustments.! WARNING