Controls; Definitions; Analog Signal; Discrete Signal - Carrier 19XRV Start-Up, Operation And Maintenance Instructions Manual

COOLER CHARGING
VALVE (HIDDEN)
COOLER
PRESSURE
TRANSDUCER
WATER
SENSOR
CABLES
CONDENSER
PRESSURE
TRANSDUCER
CONDENSER
3-WAY SHUTOFF
VALVE
CONDENSER CHARGING
VALVE (HIDDEN)

CONTROLS

Definitions

ANALOG SIGNAL — An analog signal varies in proportion
to the monitored source. It quantifies values between operating
limits. (Example: A temperature sensor is an analog device be-
cause its resistance changes in proportion to the temperature,
generating many values.)
DISCRETE SIGNAL — A discrete signal is a 2-position rep-
resentation of the value of a monitored source. (Example: A
switch produces a discrete signal indicating whether a value is
above or below a set point or boundary by generating an on/off,
high/low, or open/closed signal.)
The 19XRV hermetic centrifugal liquid chiller
General —
contains a microprocessor-based control panel that monitors
and controls all operations of the chiller. See Fig. 8 and 9. The
microprocessor control system matches the cooling capacity of
the chiller to the cooling load while providing state-of-the-art
chiller protection. The system controls the cooling load within
the set point plus the deadband by sensing the leaving chilled
water or brine temperature and regulating the inlet guide vane
via a mechanically linked actuator motor. The guide vane is a
variable flow pre-whirl assembly that controls the refrigeration
effect in the cooler by regulating the amount of refrigerant
vapor flow into the compressor. An increase in guide vane
opening increases capacity. A decrease in guide vane opening
decreases capacity. The microprocessor-based controls protect
the chiller by monitoring the digital and analog inputs and
executing capacity overrides or safety shutdowns, if required.
PIC III System Components —
system is called the PIC III (Product Integrated Control III).
See Table 1. The PIC III controls the operation of the chiller by
monitoring all operating conditions. The PIC III can diagnose a
problem and let the operator know what the problem is and
what to check. It promptly positions the guide vanes to
maintain leaving chilled water temperature. It can interface
with auxiliary equipment such as pumps and cooling tower
GUIDE VANE
CONTROL ACTUATOR
PANEL
EVAPORATOR SATURATION
TEMPERATURE SENSOR
(ON BOTTOM OF COOLER)
Fig. 8 — Chiller Controls and Sensor Locations
The chiller control
14
SPLIT RING
OIL SUMP
DIFFUSER
PRESSURE
ACTUATOR
TRANSDUCER
(OPTIONAL)
VFD COOLING
SOLENOID
VFD ENCLOSURE
fans to turn them on when required. It continually checks all
safeties to prevent any unsafe operating condition. It also regu-
lates the oil heater while the compressor is off and regulates the
hot gas bypass valve, if installed. The PIC III controls provide
critical protection for the compressor motor and controls the
VFD. The PIC III can interface with the Carrier Comfort
Network® (CCN) system if desired. It can communicate with
other PIC I, PIC II, or PIC III equipped chillers and other CCN
devices.
The PIC III consists of 3 modules housed inside 3 major
components. The component names and corresponding control
voltages are listed below (also see Table 1):
• control panel
— all extra low-voltage wiring (24 v or less)
• power panel
— 115 vac control voltage (per job requirement)
— 115 vac power for oil heater and actuators
— up to 460 vac for oil pump power
• VFD cabinet
— chiller power wiring (per job requirement)
Table 1 — Major PIC III Components and
Panel Locations*
PIC III COMPONENT
International Chiller Visual Controller
(ICVC) and Display

Chiller Control Module (CCM)

Control Transformer Circuit Breakers
CB1, CB2

Oil Heater Contactor (1C)

Oil Pump Contactor (2C)

Hot Gas Bypass Relay (3C) (Optional)
Control Transformers (T1, T2, T3)
Temperature Sensors
Pressure Transducers
*See Fig. 5-11.
OIL SUMP
TEMPERATURE
POWER
SENSOR
PANEL
OIL PUMP
DISCHARGE
PRESSURE
WATER
SENSOR
CABLES
HGBP
ACTUATOR
(OPTIONAL)
a19-1730
PANEL LOCATION
Control Panel
Control Panel
Control Panel
Power Panel
Power Panel
Power Panel
Power Panel
See Fig. 8.
See Fig. 8.