Carrier AquaEdge 19MV, Руководство по запуску, эксплуатации и техническому обслуживанию

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CONTROLS
Definitions
ANALOG SIGNAL
An
analog signal varies in proportion to the monitored source. It
quantifies values between operating limits. For example, a tem-
perature sensor is an analog device because its resistance chang-
es in proportion to the temperature, generating many values. The
signal can be either voltage or current.
DISCRETE SIGNAL
A
discrete signal is a 2-position representation of the value of a
monitored source. For example, a switch produces a discrete sig-
nal indicating whether a value is above or below a set point or
boundary by generating an on/off, high/low, or open/closed signal.
General
The 19MV centrifugal liquid chiller contains a microprocessor
based control center that monitors and controls all operations of
the chiller. The microprocessor control system matches the cool-
ing capacity of the chiller to the cooling load while providing
state-of-the-art chiller protection. The system controls cooling
load within the set point plus the dead band by sensing the leaving
chilled water or brine temperature and regulating the inlet guide
vanes and compressor speed. The guide vane is a variable flow
pre-whirl assembly that controls the refrigeration effect in the
evaporator by regulating the amount of refrigerant vapor flow into
the compressor. An increase in guide vane opening increases ca-
pacity. A decrease in guide vane opening decreases capacity. The
microprocessor-based control center protects the chiller by moni-
toring the digital and analog inputs and executing capacity over-
rides or safety shutdowns, if required. The variable frequency
drive (VFD) allows compressor start-up and capacity control by
modulating the motor frequency based on the operating condition.
PIC6 System Components
The chiller control system is called the PIC6 (Product Integrated
Control 6). See Table 1. As with previous PIC versions, the PIC6
system controls the operation of the chiller by monitoring all oper-
ating conditions. The PIC6 control system can diagnose a problem
and let the operator know what the problem is and what to check.
It positions the guide vanes and VFD speed to maintain leaving
chilled water temperature. It controls the refrigerant expansion
system for optimal chiller operation and can interface with auxilia-
ry equipment such as pumps and cooling tower fans to turn them
on when required. It communicates and interacts with the MBC
and monitors the UPS for charge level and battery health. It con-
tinually checks all safeties to prevent any unsafe operating condi-
tion. The PIC6 controls offer an operator trending function to help
the operator monitor the chiller status more easily and for critical
compressor motor protection. The PIC6 system provides open
protocols to support the competitive BMS system and can be inte-
grated into Carrier’s Lifecycle System Management for remote
monitoring and data management.
Table 1 — Major Controls Components and
Panel Locations
NOTE: For detailed information about the PIC6 HMI (human
machine interface), see the 19MV with PIC6 Controls Opera-
tion and Troubleshooting manual.
START-UP/SHUTDOWN/RECYCLE SEQUENCE
Local Start/Stop Control
Local start-up (or manual start-up) is initiated by pressing the gray
Start/Stop icon on the HMI interface. See Fig. 9.
Fig. 9 — Chiller Start/Stop Icon
This initiates the PIC6 starting sequence by displaying the list of
operating modes. Press Local On to initiate start-up. See Fig. 10.
Prior to start-up the start-to-start timer and the stop-to-start timer
must have elapsed and all alarms must be cleared (see Trouble-
shooting Guide section).
When start-up is initiated the status screen displays the start-up
progress and the Start/Stop icon
blinks green.
Fig. 10 — Local On
Once local start-up begins, the PIC6 control system performs a se-
ries of prestart tests to verify that all prestart alerts and safeties are
within acceptable limits. Table 2 shows appropriate Prestart
Alerts/Alarms conditions. If a test is not successful, the start-up is
delayed or aborted. If the prestart tests are successful, the PIC6
will perform MBC pre-start checks. After the MBC checks are
passed, the start-up will be in progress and the COMPRESSOR
RUN STATUS will be “Startup.” The system will send a com-
mand for the MBC to levitate the compressor shaft. If the com-
pressor is not ready or unable to levitate the shaft, startup will be
aborted. If successful, the control will then energize the chilled
water/brine pump relay.
Five seconds later, the condenser pump relay energizes. Thirty
seconds later the PIC6 control system monitors the chilled water
and condenser water flow devices and waits until WATER FLOW
VERIFY TIME (operator-configured, default 5 minutes) expires to
confirm flow. After flow is verified, the chilled water temperature
is compared to CONTROL POINT plus 1/2 CHILLED WATER
DEADBAND . If the temperature is less than or equal to this value,
the PIC6 control system turns off the condenser pump relay and
goes into a Recycle mode.
If the water/brine temperature is high enough, the start-up se-
quence continues and checks the guide vane position. If the guide
PIC6 COMPONENT PANEL LOCATION
Variable Frequency Drive

(Standard Tier, High Tier)
Top of condenser
Magnetic Bearing Controller (MBC) Side of compressor
Uninterrupted Power Supply (UPS) Power panel, high voltage section
Remote Monitoring Power panel, low voltage section
Power Panel On condenser, first stage end
HMI Side of cooler, first stage end