57NOTES FOR FIG. 38I General1.0 Variable Frequency Drive (VFD) shall be designed and manu-factured in accordance with Carrier engineering requirementZ-420.1.1 All field-supplied conductors and devices must be compliantand be installed in compliance with all applicable codes andjob specifications.1.2 The routing of field-installed conduit and conductors and thelocation of field-installed devices must not interfere withequipment access or the reading, adjusting, or servicing ofany component.1.3 Equipment installation and all starting and control devicesmust comply with details in equipment submittal drawingsand literature.1.4 Contacts and switches are shown in the position they wouldassume with the circuit de-energized and chiller shut down.1.5 Warning — Do not use aluminum conductors.1.6 Warning — Remove panel above VFD main circuit breakerbefore drilling. Do not drill into any other VFD cabinet panels.II Power Wiring To VFD2.0 Provide a means of disconnecting branch feeder power toVFD. Provide short circuit protection and interrupt capacity forbranch feeder in compliance with all applicable codes.2.1 Metal conduit must be used for the power wires from VFD tobranch feeder.2.2 Line side power conductor rating must meet VFD nameplatevoltage and chiller full load amps (minimum circuit ampacity).2.3 Lug adapters may be required if installation conditions dictatethat conductors be sized beyond the minimum ampacityrequired. Circuit breaker lugs will accommodate the quantity(#) and size cables (per phase) as follows.If larger lugs are required, they can be purchased from themanufacturer of the circuit breaker.2.4 Compressor motor and controls must be grounded by usingequipment grounding lug provided inside unit-mounted VFDenclosure.III Control Wiring3.0 Field-supplied control conductors to be at least 18 AWG orlarger.3.1 Ice build start/terminate device contacts, remote start/stopdevice contacts, and spare safety device contacts (devicesnot supplied by Carrier) must have 24 vac rating. Max currentis 60 mA; nominal current is 10 mA. Switches with gold-plated bifurcated contacts are recommended.3.2 Remove jumper wire between TB1-19 and TB1-20 beforeconnecting auxiliary safeties between these terminals.3.3 Each integrated contact output can control loads (VA) forevaporator pump, condenser pump, tower fan low, tower fanhigh, and alarm annunciator devices rated 5 amps at 115 vacand up to 3 amps at 250 vac.Do not use control transformers in the VFD enclosure orpower panel as the power source for external or field-suppliedcontactor coils, actuator motors, or any other loads.3.4 Do not route control wiring carrying 30 v or less within a con-duit which has wires carrying 50 v or higher or along sidewires carrying 50 v or higher.3.5 Spare 4 to 20 mA output signal is designed for controllerswith a non-grounded 4 to 20 mA input signal and a maximuminput impedance of 500 ohms.CAUTIONTo prevent damage to machine, do NOT punch holes or drill intothe top surface of the starter enclosure for field wiring. Knock-outs are provided on the side of the starter enclosure for fieldwiring connections.VFDMAX INPUTAMPSSTANDARD 65KAICLUG CAPACITY(PER PHASE)OPTIONAL 100KAICLUG CAPACITY(PER PHASE)NO. OFCONDUCTORSCONDUCTORRANGENO. OFCONDUCTORSCONDUCTORRANGE442A 3 2/0 — 400MCM 3 2/0 — 400MCM608A 3 2/0 — 400MCM 3 2/0 — 400MCM900A 4 1/0 — 750MCM 4 1/0 — 750MCM1200A 4 1/0 — 750MCM 4 1/0 — 750MCMCAUTIONControl wiring for Carrier to start pumps and tower fan motorsand establish flows must be provided to assure machine protec-tion. If primary pump, tower fan, and flow control is by othermeans, also provide parallel means for control by Carrier. Fail-ure to do so could result in machine freeze-up or overpressure.