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STARTING EQUIPMENT
The 19XR chiller requires a motor starter or VFD to operate the
centrifugal hermetic compressor motor. The starter or VFD have
communication wiring between itself and Carrier power panel
(19XR3-E) or Carrier control panel (19XR6-7).
See Carrier's specifications for specific starter/VFD require-
ments. All starters/VFDs must meet these specifications in order
to properly start and satisfy mechanical safety requirements.
There may be multiple circuit breakers inside the starter. These in-
clude the main compressor motor circuit breaker, a circuit breaker
which provides power to the chiller control panel, and a possible
circuit breaker for starter specific controls. The control breaker(s)
are typically wired in parallel with the first so that power is provid-
ed to those services when the main breaker is open. The discon-
nect switch on the starter front cover is connected to the main
breaker. For 19XR3-E units it is typical that the starter provides
control power and if specified 3-phase power to the oil pump (for
medium/high voltage there is an option for a transformer). For
19XR6-7 it is typical that 3-phase power is field supplied to the
Carrier control panel which powers oil-pump, heater and controls.
Consult specific wiring diagrams for details.
WARNING
The main circuit breaker on the front of the starter/VFD
disconnects the main motor power only. Power may be still
energized for other circuits. Always check wiring diagrams
before initiating any work on the chiller and follow applicable
lock-out/tag-out procedures. Failure to disconnect power will
result in personal injury.
Unit-Mounted VFDs
The 19XR3-E starter options include a variable frequency drive
motor controller mounted on the condenser. These unit-mounted
VFDs are offered with low voltage motors between 380 and 575
vac. It reduces the starting current inrush by controlling the volt-
age and frequency to the compressor motor. Once the motor has
accelerated to minimum speed, the PIC6 modulates the compres-
sor speed and guide vane position to control chilled water
temperature.
Operational parameters and fault codes are displayed relative to
the drive. Refer to specific drive literature along with trouble-
shooting sections (consult VFD nameplate on inside of door if
uncertain of drive model). The display is also the interface for
entering specific chiller operational parameters. These parame-
ters have been preprogrammed at the factory. An adhesive-
backed label on the inside of the drive has been provided for ver-
ification of the specific job parameters. See Initial Start-Up
Checklist section for details.
NOTE: The factory offers a variety of unit-mounted VFDs. Liqui-
Flo2 is an active front end drive while PowerFlex 755, VLT
HVAC FC-102, and PowerFlex 700L are 6-pulse passive rectifier
drives. Consult Carrier Specification Z-420 and Z-417 respective-
ly, along with drive-specific literature for details.
Unit-Mounted Starters
The 19XR3-E chiller offers unit-mounted wye-delta and solid
state starters. See Carrier Specification Z-415 for specific starter
requirements.
Typically three separate circuit breakers are inside the starter. This
includes (1) the main compressor motor circuit breaker, (2) a cir-
cuit breaker which provides power to chiller controls and the oil
heater (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 to
those services when the main breaker is open. The disconnect
switch on the starter front cover is connected to the main breaker.
Solid-State Starter
The main circuit breaker on the front of the starter disconnects
the main motor power only. Power is still energized for two
other circuits. Two additional circuit breakers inside of the
starter must be turned off to disconnect power to the oil pump,
PIC6 controls, and the oil heater. Failure to disconnect power
will result in personal injury.
The 19XR chiller may be equipped with a solid-state, reduced
voltage starter. This starter's primary function is to provide on-off
control of the compressor motor. This type of starter reduces the
peak starting torque, controls the motor inrush current, and de-
creases mechanical shock. This capability is summed up by the
phrase "soft starting." Consult eCat for full information about
starter 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 the
starting voltage. The starting torque of a motor at full voltage is
typically 125% to 175% of the running torque. When the voltage
and the current are reduced at start-up, the starting torque is re-
duced as well. The object is to reduce the starting voltage to adjust
the 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 desired
period of time. Once full voltage is reached, a bypass contactor is
energized to bypass the SCRs.
When voltage is supplied to the solid-state circuitry (CB1 is
closed), the heat sinks in the starter as well as the wires leading
to the motor and the motor terminal are at line voltage. Do not
touch the heat sinks, power wiring, or motor terminals while
voltage is present or serious injury will result.
The display on the front of the solid-state or wye-delta starter
is 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 state
Wye-Delta Starter
The 19XR chiller may be equipped with a wye-delta starter
mounted on the unit. This starter is used with low-voltage motors
(under 600 v). It reduces the starting current inrush by connecting
each phase of the motor windings into a wye configuration. This
occurs during the starting period when the motor is accelerating up
to speed. Once the motor is up to speed, the starter automatically
connects 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 be
located as follows:
Benshaw MX
3
Low Voltage Solid-State Starter Manual -
HVACPartners Form Number = 890003-06-01
Benshaw MX
3
Low Voltage Wye-Delta Starter Manual -
HVACPartners Form Number = 890003-07-02
16
WARNING
WARNING
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