Carrier AquaEdge 19XR Series Start-up, Operation And Maintenance Instructions Manual

Also see for AquaEdge 19XR series: Installation instructions Start-up, operation and maintenance instructions

Contents

20Unit-Mounted StartersThe 19XR2-E chiller offers unit-mounted wye-delta and solidstate starters. See Carrier Specification Z-415 for specific starterrequirements.Typically three separate circuit breakers are inside the starter. Thisincludes (1) the main compressor motor circuit breaker, (2) a cir-cuit breaker which provides power to chiller controls and the oilheater (provided at 115 vac), and (3) a circuit breaker which pro-vides power at line voltage to the oil pump. The latter two are typ-ically wired in parallel with the first so that power is provided tothose services when the main breaker is open. The disconnectswitch on the starter front cover is connected to the main breaker.Solid-State StarterThe 19XR chiller may be equipped with a solid-state, reducedvoltage starter. This starter’s primary function is to provide on-offcontrol of the compressor motor. This type of starter reduces thepeak starting torque, controls the motor inrush current, and de-creases mechanical shock. This capability is summed up by thephrase “soft starting.” Consult E-Cat for full information aboutstarter offerings. The solid-state starter manufacturer’s name is lo-cated inside the starter access door.A solid-state, reduced-voltage starter operates by reducing thestarting voltage. The starting torque of a motor at full voltage istypically 125% to 175% of the running torque. When the voltageand the current are reduced at start-up, the starting torque is re-duced as well. The object is to reduce the starting voltage to adjustthe voltage necessary to develop the torque required to get the mo-tor moving. The voltage is reduced by silicon controlled rectifiers(SCRs). The voltage and current are then ramped up in a desiredperiod of time. Once full voltage is reached, a bypass contactor isenergized to bypass the SCRs.The display on the front of the solid-state or wye-delta starteris useful for troubleshooting and starter checkout. The dis-play indicates:• line voltage• control voltage status• power indication• proper phasing for rotation• start circuit energized• ground fault• current unbalance• run stateWye-Delta StarterThe 19XR chiller may be equipped with a wye-delta startermounted on the unit. This starter is used with low-voltage motors(under 600 v). It reduces the starting current inrush by connectingeach phase of the motor windings into a wye configuration. Thisoccurs during the starting period when the motor is accelerating upto speed. Once the motor is up to speed, the starter automaticallyconnects the phase windings into a delta configuration. When con-nected in delta the currents through the motor windings is 1/√(3)(57.7%) of line current.Additional information about current unit-mounted starters can belocated as follows:Benshaw MX3 (TM) Low Voltage Solid-State Starter Manual -HVACPartners Form Number = 890003-06-00)Benshaw MX3 (TM) Low Voltage Wye-Delta Starter Manual -HvacPartners Form Number = 890003-07-01)Free-Standing Starters/VFDsIn addition to unit-mounted starters the 19XR product line offersfree-standing starter types of Across the Line, Solid State, Auto-Transformer and VFD. 19XR6-7 are only offered with free-stand-ing starters/VFDs. For free-standing starters/VFDs refer to jobsubmittal drawings.CONTROLSDefinitionsANALOG SIGNALAn analog signal varies in proportion to the monitored source. Itquantifies values between operating limits. (Example: A tem-perature sensor is an analog device because its resistance chang-es in proportion to the temperature, generating many values.)DISCRETE SIGNALA discrete signal is a 2-position representation of the value of amonitored source. (Example: A switch produces a discrete signalindicating whether a value is above or below a set point or bound-ary by generating an on/off, high/low, or open/closed signal.)GeneralThe 19XR centrifugal liquid chiller contains a microprocessor-based control center that monitors and controls all operations ofthe chiller. The microprocessor control system matches the cool-ing capacity of the chiller to the cooling load while providingstate-of-the-art chiller protection. The system controls coolingload within the set point plus the deadband by sensing the leavingchilled water or brine temperature and regulating the inlet guidevane via a mechanically linked actuator motor. The guide vane is avariable flow pre-whirl assembly that controls the refrigeration ef-fect in the cooler by regulating the amount of refrigerant vaporflow into the compressor. An increase in guide vane opening in-creases capacity. A decrease in guide vane opening decreases ca-pacity. Additionally if a unit is equipped with VFD then the con-troller will control both compressor speed and guide vane for opti-mum efficiency at a particular load. The microprocessor-basedcontrol center protects the chiller by monitoring the digital and an-alog inputs and executing capacity overrides or safety shutdowns,if required.PIC 6 System ComponentsThe chiller control system is called the PIC 6 (Product IntegratedControl 5). See Table 2. As with previous PIC versions, the PIC6 system controls the operation of the chiller by monitoring alloperating conditions. The PIC 6 control system can diagnose aproblem and let the operator know what the problem is and whatto check. It positions the guide vanes to maintain leaving chilledwater temperature. It interfaces with auxiliary equipment such aspumps and cooling tower fans to turn them on when required. Itcontinually checks all safeties to prevent unsafe operating condi-tions. It also regulates the oil heater while the compressor is offand regulates the envelope control (HGBP) and any other auto-matic valves, if installed. The PIC 6 controls provide critical pro-tection for the compressor motor and control the motor starter.WARNINGThe main circuit breaker on the front of the starter disconnectsthe main motor power only. Power is still energized for twoother circuits. Two additional circuit breakers inside of thestarter must be turned off to disconnect power to the oil pump,PIC 6 controls, and the oil heater. Failure to disconnect powerwill result in personal injury.WARNINGWhen voltage is supplied to the solid-state circuitry (CB1 isclosed), the heat sinks in the starter as well as the wires leadingto the motor and the motor terminal are at line voltage. Do nottouch the heat sinks, power wiring, or motor terminals whilevoltage is present or serious injury will result.