Carrier AquaEdge 19DV series Operating instructions

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.
Catalog No. 04-53190083-01 Printed in U.S.A. Form 19DV-CLT-5T Pg 1 5-21 Replaces: 19DV-CLT-4T
Controls Operation and Troubleshooting
SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . 1
GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Abbreviations Used in This Manual . . . . . . . . . . . . . . 2
HARDWARE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Main Control Board . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
SIOB (Starfire Input/Output Board) . . . . . . . . . . . . . . 2
IOB (Input/Output Board) . . . . . . . . . . . . . . . . . . . . . . 2
Communication Cables . . . . . . . . . . . . . . . . . . . . . . . 11
Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Controls Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
USER INTERFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Web Connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
General Interface Features . . . . . . . . . . . . . . . . . . . . 12
CONTROL OPERATION . . . . . . . . . . . . . . . . . . . . . . . 16
Start-Stop Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Compressor Run Status . . . . . . . . . . . . . . . . . . . . . . 16
Chiller Start-Up Sequence. . . . . . . . . . . . . . . . . . . . . 16
Chiller Shutdown Sequence . . . . . . . . . . . . . . . . . . . 17
Refrigerant Lubrication Control . . . . . . . . . . . . . . . . 17
Control Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Displaying Data Trends . . . . . . . . . . . . . . . . . . . . . . . 26
Hydraulic Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
DIAGNOSTICS AND TROUBLESHOOTING . . . . . . . 27
Alarm/Alert Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Displaying Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Resetting Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Event States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
CONTROLLER SETTINGS . . . . . . . . . . . . . . . . . . . . . 42
Unit IP Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
System Configuration . . . . . . . . . . . . . . . . . . . . . . . . 43
COMMUNICATION PROBLEMS . . . . . . . . . . . . . . . . 43
Hardware Problems . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Web Interface Problems . . . . . . . . . . . . . . . . . . . . . . 43
Ethernet/IP Connection Problems . . . . . . . . . . . . . . 44
APPENDIX A —PIC6 SCREEN AND TABLE
STRUCTURE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
APPENDIX B —IOB AND HMI DIP SWITCH
SETTINGS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
APPENDIX C —INPUT/OUTPUT BOARD (IOB)
STATUS INDICATORS . . . . . . . . . . . . . . . . . . . . . . 83
APPENDIX D —NETWORK CONFIGURATION . . . . 84
SAFETY CONSIDERATIONS
Installing, starting up, and servicing this equipment can be haz-
ardous due to system pressures, electrical components, and
equipment location (roof, elevated structures, etc.). Only trained,
qualified installers and service mechanics should install, start up,
and service this equipment. When working on this equipment,
observe precautions in the literature, and on tags, stickers, and
labels attached to the equipment, and any other safety precau-
tions that apply. Follow all safety codes. Wear safety glasses and
work gloves. Use care in handling, rigging, and setting this
equipment, and in handling all electrical components.
DANGER
ELECTRICAL SHOCK HAZARD
Failure to follow this warning will result in personal injury
or death.
Before performing service or maintenance operations on
unit, turn off main power switch to unit and install lock(s)
and lockout tag(s). Ensure electrical service to rooftop unit
agrees with voltage and amperage listed on the unit rating
plate. Unit may have more than one power switch.
WARNING
Electrical currents cause components to get hot either tempo-
rarily or permanently and may cause burns. Handle power
cable, electrical cables and conduits, terminal box covers,
and motor frames with great care.
CAUTION
This unit uses a microprocessor control system. Do not
short or jumper between terminations on circuit boards or
modules; control or board failure may result.
Be aware of electrostatic discharge (static electricity) when
handling or making contact with circuit boards or module con-
nections. Always touch a chassis (grounded) part to dissipate
body electrostatic charge before working inside control center.
Use extreme care when handling tools near boards and
when connecting or disconnecting terminal plugs. Circuit
boards can easily be damaged. Always hold boards by the
edges and avoid touching components and connections.
This equipment uses, and can radiate, radio frequency energy.
If not installed and used in accordance with the instruction
manual, it may cause interference to radio communications.
The PIC6 control boards have been tested and found to com-
ply with the limits for a Class A computing device pursuant to
International Standard in North America EN 61000-2/3 which
are designed to provide reasonable protection against such in-
terference when operated in a commercial environment. Oper-
ation of this equipment in a residential area is likely to cause
interference, in which case the user, at his own expense, will
be required to take whatever measures may be required to cor-
rect the interference.
Always store and transport replacement or defective boards
in anti-static shipping bag.
AquaEdge®
19DV Two-Stage High-Efficiency
Semi-Hermetic Centrifugal Liquid Chillers
with PIC6 Controls

2
GENERAL
This publication contains operation and troubleshooting infor-
mation for PIC (Product Integrated Control) 6, a system for
controlling 19DV semi-hermetic centrifugal liquid chillers.
This publication is based on 19DVPIC6.
The PIC6 control system monitors and controls all operations
of the chiller. The microprocessor control system matches the
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 or minus the dead band by sensing the
water or brine temperature and regulating the inlet guide vane
via a mechanically linked actuator motor, and regulating VFD
(variable frequency drive) speed of the compressor. The guide
vane is a variable flow pre-whirl assembly that controls the re-
frigeration effect in the evaporator 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
control center protects the chiller by monitoring the digital and
analog inputs and executing capacity overrides or safety shut-
downs as necessary.
The PIC6 control system also provides access to a Control Test
function covering all outputs except compressor relay outputs.
NOTE: This software is shared between multiple product families
and therefore not all points indicated in the tables are applicable to
19DV or 19XR as configured. For instance 19DV is not an oil lu-
bricated machine, so any reference to oil in the software tables
would not be applicable for 19DV.
Abbreviations Used in This Manual
The following abbreviations are used in this manual:
HARDWARE
The PIC6 control system consists of one main control board,
an input/output board (IOB) for purge control, and four IOB
modules. All boards communicate via an internal Local Equip-
ment Network (LEN) bus.
Main Control Board
The main control board is supplied from a 24 VAC supply refer-
ence to earth ground. In the event of a power supply interrupt,
the unit restarts automatically without the need for an external
command. However, any faults active when the supply is inter-
rupted are saved, and may in certain cases prevent a circuit or
unit from restarting. Figure 1 shows the main control interface
and connectors.
NOTES:
1. Either BACnet/MSTP or BACnet/IP can be enabled and either
Modbus/RTU or Modbus/TCP/IP can be enabled. Controller does
not allow both to be enabled at the same time.
2. Modbus RTU can be configured simultaneously with BACnet IP.
3. BACnet MS/TP can be configured simultaneously with Modbus TCP/IP.
Fig. 1 — PIC6 Connectors
SIOB (Starfire Input/Output Board)
The SIOB is the purge control module, supplied from a 24VAC
supply reference to earth ground.
IOB (Input/Output Board)
The IOB is supplied from a 24 VAC supply reference to earth
ground.
IOB CONFIGURATION
The input/output boards can be configured for different types
of input/output. If an input or output type is supported for the
specific channel then it can be modified in the Configuration
Menu as shown in Table 1.
AWG —American Wire Gage
CCM —Chiller Control Module
CCN mode —Operating mode: CCN
CCN —Carrier Comfort Network®
DHCP —Dynamic Host Configuration Protocol
DSH —Discharge Superheat
EC —Envelope Control (Hot Gas Bypass)
ECDW —Entering Condenser Water
ECW —Entering Chilled Water
EWT —Entering Water Temperature
HGBP —Hot Gas Bypass
HMI —Human Machine Interface
I/O —Input/Output
IOB —Input/Output Board
LCDW —Leaving Condenser Water
LCW —Leaving Chilled Water
LED —Light-Emitting Diode
LEN —Local Equipment
MCB —Main Control Board
NIC —Network Interface Card
PIC —Product Integrated Control
RLA —Rated Load Amps
RTD —Resistance Temperature Detector
SIOB —Starfire Input/Output Board
TFT —Thin Film Transistor
UI —User Interface
VFD —Variable Frequency Drive
CAUTION
Maintain the correct polarity when connecting the power sup-
ply to the boards. Otherwise, the boards may be damaged.
LEGEND
J1 — USB CONNECTOR
J5 — USB CONNECTOR
J6 — LEN CONNECTOR
J7 — CCN CONNECTOR
J8 — RS485, BACnet MS/TP OR Modbus RTU
J9 — RNET (future)
J10 — RS485
J11 — USB CONNECTOR
J14 — POWER SUPPLY CONNECTOR (24 VAC)
J15 —ETHERNET CONNECTOR, PORT 0 (DEFAULT
IP: 169.254.1.1, Mask: 255.255.0.0)
J16 — ETHERNET CONNECTOR, PORT 1 (DEFAULT
IP: 192.168.100.100, mask: 255.255.255.0)

3
Table 1 — IOB Configuration 19DV IOB COMPONENTS AND WIRING
The components listed in Tables 2-5 are available at the user’s
terminal block on the IOB. Some are available only if the unit
is operating in Remote mode. Table 6 lists SIOB inputs and out-
puts. Figures 2-4 show IOB wiring diagrams and Fig. 5 is the
legend. Figures 6-9 show additional control wiring.
Table 2 — 19DV IOB1 Connections
NOTES:
1. See Fig. 2 for IOB1 wiring diagram.
2. For pressure readings, only Vout (output) terminal is indicated. See Fig. 2 for
Vin (+) and ground (–).
3. Defaults are shown. In some cases the IOB can be configured differently
depending on job requirements.
Table 3 — 19DV IOB2 Connections
NOTES:
1. See Fig. 3 for IOB2 wiring diagram.
2. For pressure readings, only Vout (output) terminal is indicated. See Fig. 3 for
Vin (+) and ground (–).
3. Defaults are shown. In some cases the IOB can be configured differently
depending on job requirements.
ANALOG INPUT ANALOG OUTPUT
0Disable 0Disable
10 to 5 VDC 14 to 20 mA
24 to 20 mA 20 to 10 VDC
310 k(thermistor)
45 k(thermistor)
5Ohm (Shift_Dis)
6100 Ohm RTD
DESCRIPTION CHANNEL TERMINAL TYPE OPTIONAL
Entering Chilled Water Temperature AI1 J16-1,5 5 k—
Leaving Chilled Water Temperature AI2 J16-2,6 5 k—
Entering Condenser Water Temperature AI3 J16-3,7 5 k—
Leaving Condenser Water Temperature AI4 J16-4,8 5 k—
Evaporator Refrigerant Liquid Temperature AI5 J15-6,12 5 k—
Discharge Gas Temperature AI6 J15-5,11 5 k—
Condenser Pressure AI7 J15-4,10 5 VDC —
Evaporator Pressure AI8 J15-3,9 5 VDC —
Economizer Pressure AI9 J15-2,8 5 VDC Yes
Chiller Status Output (ON=20mA, OFF=4mA, TRIPOUT=8mA,
Not Off and Compressor not running=12mA) AO1 J14-1,4 4 to 20 mA Yes
Evaporator Flow Switch DI1 J13-5 (5TB-9,10) 24 VAC Yes, NO (dry contact); closed indicates Flow
Condenser Water Flow Switch DI2 J13-6 (5TB-11,12) 24 VAC Yes, NO (dry contact); closed indicates Flow
Remote Contact DI3 J13-7 (5TB-13,14) 24 VAC Yes, NO (dry contact);
closed indicates start chiller signal
Remote Emergency Stop Input DI4 J13-8 (5TB-15, 16) 24 VAC Yes, NO (dry contact);
closed indicates stop chiller signal
Economizer Bypass Valve DO1 J12-7 24 VAC Yes
Refrigerant Pump DO2 J12-10 24 VAC —
Chiller Alarm Relay DO3 J12-2 (5TB-3,4) 24 VAC Yes
Free Cooling Valve DO4 J12-5 24 VAC Yes
LEGEND
IOB —Input/Output Board
NO —Normally Open
SV —Solenoid Valve
DESCRIPTION CHANNEL TERMINAL TYPE OPTIONAL
Condenser Refrigerant Vapor Temp AI2 5 KOhm Yes
Motor Winding Temperature 1 AI1 J16-1,5 5 k—
EC/HGBP Valve Feedback AI3 J16-3,7 4 to 20 mA Yes
Pump Output Pressure AI5 J15-6,12 5 VDC —
Bearing Outlet Pressure AI6 J15-5,11 5 VDC —
Bearing Inlet Pressure AI7 J15-4,10 5 VDC —
Auto Demand Limit Input AI8 J15-3,9 (5TB-23,24) 4 to 20 mA Yes
Refrigerant Leak Sensor AI9 J15-2,8 (5TB,25,26) 4 to 20 mA Yes
Pump Input Pressure AI10 J15-1,7 5 VDC —
Guide Vane 1 Output AO1 J14-1,4 4 to 20 mA —
EC/HGBP Modulating Output AO3 J14-3,6 4 to 20 mA Yes
Liquid Level Switch DI2 J13-6 24 VAC —
High Pressure Switch DI3 J13-7 24 VAC —
Ice Build Contact DI4 J13-8,4, (5TB-17,18) 24 VAC Yes, NO (dry contact)
Condenser Control Valve DO1 J12-7 24 VAC —
Evaporator Control Valve DO2 J12-10 24 VAC —
VFD Run/Stop Interlock DO3 J12-2 24 VAC Yes
Economizer Isolation Valve (Liquid Bypass Option) DO4 J12-5 24 VAC —
LEGEND
EC —Envelope Control
HGBP —Hot Gas Bypass
IOB —Input/Output Board
NO —Normally Open

4
Table 4 — 19DV IOB3 Connections
NOTES:
1. See Fig. 3 for IOB3 wiring diagram.
2. For pressure readings, only Vout (output) terminal is indicated. See Fig. 3 for
Vin (+) and ground (–).
3. Defaults are shown. In some cases the IOB can be configured differently
depending on job requirements.
Table 5 — 19DV IOB4 Connections
NOTES:
1. See Fig. 4 for IOB4 wiring diagram.
2. For pressure readings, only Vout (output) terminal is indicated. See Fig. 4 for
Vin (+) and ground (–).
3. Defaults are shown. In some cases the IOB can be configured differently
depending on job requirements.
Table 6 — SIOB Input/Output Descriptions
DESCRIPTION CHANNEL TERMINAL TYPE OPTIONAL
1st Stage Bearing Temperature AI1 J16-1,5 5 k—
2nd Stage Bearing Temperature AI2 J16-2,6 5 k—
Guide Vane 2 Actual Position AI4 J16-4,8 4 to 20 mA —
Remote Reset Temperature AI5 J15-6,12 (5TB-27,28) 5 kYes
Guide Vane 1 Actual Position AI6 J15-5,11 4 to 20 mA —
Common Chilled Water Supply (CHWS) Temperature AI7 J15-4, 10 (5TB,29,30) 5 kYes
Auto Water Temperature Reset AI8 J15-3,9 (5TB-31,32) 4 to 20 mA Yes
Common Chilled Water Return (CHWR) Temperature AI9 J15-2, 8 (5TB-37,38) 5 kYes
Head Pressure Output AO1 J14-1,4 4 to 20 mA Yes
Head Pressure Output2 AO2 HDPV_OU2 4 to 20 mA Yes
Guide Vane 2 Output AO3 J14-3, 6 (5TB-5,6) 4 to 20 mA No
Spare Safety DI3 J13,7 (5TB-19,20) 24 VAC Yes, NO (dry contact)
Chiller Run Status Output (OFF=0V, ON, ON=24 VAC) DO1 J13-7 24 VAC Yes
Chilled Water Pump DO3 J12-2 (5TB-5,6) 24 VAC Yes
Condenser Water Pump DO4 J12-5 (5TB-7,8) 24 VAC Yes
LEGEND
IOB —Input/Output Board
NO —Normally Open
DESCRIPTION CHANNEL TERMINAL TYPE OPTIONAL
Entering Evaporator Water Pressure /
Chilled Water Delta P AI3 J16-7(5TB51, 52) 5 VDC Yes
Leaving Evaporator Water Pressure /
Condenser Water Delta P AI4 J16-8(5TB-48, 49) 5 VDC Yes
Entering Condenser Water Pressure AI5 J15-6(5TB-45, 46) 5 VDC Yes
Leaving Condenser Water Pressure AI6 J15-5(5TB-42, 43) 5 VDC Yes
Evaporator Water Flow Measurement AI8 J15-3, 9(5TB-53, 54) 4 to 20 mA Yes
Condenser Water Flow Measurement AI9 J15-2, 8(5TB-55, 56) 4 to 20 mA Yes
Chilled Water Pump (Variable) AO1 J14-1, 4 (5TB-57, 58) 4 to 20 mA —
Condenser Water Pump (Variable) AO2 J14-2, 5 (5TB-59, 60) 4 to 20 mA —
Tower Fan (Variable) AO3 J14-3, 6 (5TB-61, 62) 4 to 20 mA —
Customer Alert DI3 J13-3, 7 (5TB-63,64) 24 VAC Yes, NO (dry contact)
Free Cooling Start Switch DI4 J13-4, 8 (5TB-65,66) 24 VAC Yes, NO (dry contact)
Free Cooling Mode DO1 J12-7 (5TB-67) 24 VAC —
Power Request Output DO2 J12-10 (5TB-68) 24 VAC —
Tower Fan High DO3 J12-2 (5TB-69) 24 VAC Yes
Tower Fan Low DO4 J12-5 (5TB-70) 24 VAC Yes
LEGEND
IOB —Input/Output Board
NO —Normally Open
DESCRIPTION CHANNEL TERMINAL TYPE OPTIONAL
Purge Compressor Suction Temperature AI1 J25-1,2 5 k—
Purge Level Switch Low Relay DI1 J1-1, 2 24 VAC —
Purge Level Switch High Relay DI2 J1-3, 4 24 VAC —
Purge Condenser Valve DO1 J2-2 24 VAC —
Purge Compressor Valve DO2 J2-1 24 VAC —
Purge Pumpout Valve DO3 J6-2 24 VAC —
Purge Drainage Valve DO4 J6-1 24 VAC —
Purge Regeneration Valve DO5 J23-2 24 VAC —
Purge Discharge Valve DO6 J22-2 24 VAC —
Purge Vacuum Pump Relay DO7 J7-7, 8 24 VAC —
Purge Compressor Contactor DO8 J7-5, 6 24 VAC —
Purge Idle Drain Control Valve DO9 J7-2,4 24 VAC —
Purge Heater Contactor DO10 J7-1, 2 24 VAC —

5
Fig. 2 — IOB 1
19XV05005503 BASE DIMENSIONS
(REFERENCE)
DIMENSIONS IN INCHES [MM]
A19-2265
NOTE: A suitable 24 VAC relay is Carrier part number
19XV05005503. Carrier recommends using a relay with
a contact rating of 10 amp sealed RMS or greater.
LEGEND FOR FIG. 2-6
Molex Connector Assembly
MOLEX CONNECTOR
ASSEMBLY PART NO.
(SHORT WIRE INCLUDED
NO.
OF
PINS
19XF04003501 2
19XF04003502 4
19XF04003503 6
19XF04003504 8
19XF04003505 10
19XF04003506 12

6
Fig. 3 — IOB2 and IOB3

7
Fig. 4 — IOB 4

8
Fig. 5 — 19DV Control Panel Abbreviations

9
Fig. 6 — 19DV Control Wiring
FROM
NOTE: Jumper wires installed only on 60 Hz units.
When jumper wires are installed, the power wiring
from the VFD to PP1 and PP2 is not installed.

10
Fig. 7 — HMI Panel
Fig. 8 — 19DV Control Panel
Fig. 9 — 19DV Purge Panel
a19-2251
7TB IN HMI PANEL
FOR CUSTOMER
COMMUNICATION
CCN CONNECTION
A (+)
C (G)
B (-)
REFRIG PUMP POWER
CTL POWER
ECONOMIZER VENT POWER
GUIDE VANE 1
HMI GROUND
HMI COMMUNICATION
HMI POWER
INTERLOCK -
VFD/CONTROL PANEL
COMMUNICATION -
VFD/CONTROL PANEL
PURGE POWER
FREE COOLING
ENVELOPE CONTROL (HGBP)
REFRIGERANT PUMP POWER
ECONOMIZER BYPASS
GUIDE VANE 2

11
Communication Cables
The communication transmission cables have the following
electrical characteristics:
• 2 signal conductors and one ground conductor of 20 AWG
or larger, 100% shielded
• One tinned copper braid (65% coverage)
Recommended cables are shown below:
To avoid potential interference, route communication cables
between the starter and the chiller control panels as far away as
possible from high voltage cable and other likely disturbances.
Always separate communication cables from other cables and
always run wiring as directly as possible.
Sensors
PRESSURE TRANSDUCERS
Pressure transducers measure and control the pressures in the
unit. These electronic sensors deliver 0 to 5 VDC. The trans-
ducers can be calibrated through the controller. The pressure
transducers are connected to the IOBs. See Table 7.
TEMPERATURE SENSORS
The system uses electronic sensors to measure and control the
temperatures in the unit. There are three types of temperature
sensors: 5K thermistor, 10K thermistor, and RTD (resistance
temperature detector, 100 ohm, 3-wire) based on IOB channel
configurations. The temperature sensor range is –40°F (–40°C)
to 245°F (118°C). See Table 8.
Controls Outputs
EVAPORATOR/CONDENSER WATER PUMP
The controller regulates the evaporator/condenser water pump.
Note that Carrier requires full or parallel pump control.
INLET GUIDE VANE
The inlet guide vane adjusts the refrigerant vapor flow into the
compressor to adapt to change in the operating conditions of the
machine. To adjust the refrigerant flow, the guide vane opens or
closes to vary the cross-section of the refrigerant path. The high
degree of accuracy with which the guide vane is positioned en-
sures that the flow of refrigerant is precisely controlled.
ECONOMIZER ISOLATION VALVE (OPTION)
The economizer is an on/off valve that shuts off the economiz-
er gas vent line leading to the second stage of the compressor.
ECONOMIZER LIQUID BYPASS VALVE (OPTION)
The economizer liquid bypass valve is opened if lift difference
between condenser and evaporator is small. When the valve is
open liquid refrigerant can bypass the economizer and flow di-
rectly from the condenser to the evaporator and thereby avoid
the pressure loss associated with the economizer.
ENVELOPE/HGBP CONTROL VALVE
The modulating Envelope Control valve artificially loads the
chiller and keeps it running under low load conditions or helps
to prevent surge conditions. Since this function can also reduce
the operating efficiency of the machine, this is a user-selectable
and configurable option.
VFD
The VFD modifies motor frequency to allow compressor start-up
and capacity control. The VFD controls continually monitor pa-
rameters to ensure compressor protection. If a problem occurs, the
controller triggers an alarm and the compressor is stopped.
FREE COOLING VALVE (OPTION)
The free cooling control allows the chiller to provide cooling
without running the compressor. The free cooling vent valve is
opened, allowing the refrigerant to bypass the compressor and
go straight from the evaporator to the condenser. This control
mode can only be used when the chiller is OFF and the external
air temperature is low enough to support this operation.
TOWER FAN HIGH/LOW
The controls provide optional fan tower control by a 24 VAC
output for tower fan low and another for tower fan high speed.
Table 7 — Pressure Transducers
Table 8 — Temperature Sensors
* Separate inputs used when the chiller is in network mode.
NOTE: Text in parentheses indicates applicable product.
USER INTERFACE
The PIC6 Human Machine Interface (HMI) is a color 10.4-in.
TFT touch screen. Navigation is either direct from the touch
screen interface or by connecting to a web interface at the
Ethernet IP port of the controller. The navigation menus are the
same for both connection methods.
Web Connection
Two web connections may be authorized at the same time. When
two users are connected simultaneously, there is no priority be-
tween users; that is, the last modification is in effect regardless
USAGE CABLE
Intra-Building Belden 8772
High Temperature Belden 85240
Plenum Belden 89418
PRESSURE
TRANSDUCER PURPOSE
Pump Input
Pressure
Measures the pressure at the input of the refrigerant
pump
Pump Output
Pressure
Measures the pressure at the output of the refrigerant
pump
Bearing Inlet
Pressure
Measures the pressure at the bearing inlet
Bearing Outlet
Pressure
Measures the pressure at the bearing outlet
Evaporator Measures evaporator pressure
Condenser Measures condenser pressure
Economizer Measures economizer pressure
Evaporator Water
Pressure Difference
(Optional) Measures pressure difference between entering
and leaving water.
Condenser Water
Pressure Difference
(Optional) Measures pressure difference between entering
and leaving water.
Evaporator Entering
Water
(Optional) Measures pressure of evaporator entering
water
Evaporator Leaving
Water
(Optional) Measures pressure of evaporator leaving water
Condenser Entering
Water
(Optional) Measures pressure of condenser entering
water
Condenser Leaving
Water
(Optional) Measures pressure of condenser leaving water
TEMPERATURE SENSOR PURPOSE
Entering Chilled Water Measures entering evaporator water temperature
Leaving Chilled Water Measures leaving evaporator water temperature
Entering Condenser Water Measures entering condenser water temperature
Leaving Condenser Water Measures leaving condenser water temperature
Evaporator Refrigerant
Liquid
Measures evaporator refrigerant liquid temperature
Compressor Discharge Measures compressor discharge temperature
1st Stage Bearing Measures the temperature of the bearings in the
first stage of the compressor
2nd Stage Bearing Measures the temperature of the bearings in the
second stage of the compressor
Bearing Refrigerant Supply
(available for older software
only)
Measures the temperature of the refrigerant sup-
ply for the bearings
Chilled Water Supply
(Optional)*
Measures the temperature of the chilled water
supply
Chilled Water Return
(Optional)*
Measures the temperature of the chilled water
return
Motor Winding Measures the temperature of each phase of the
compressor motor

12
of the user. Connection is from a personal computer using a
Java-enabled web browser. See “CONTROLLER SETTINGS”
on page 42 for configuration instructions.
The minimum browser configuration includes:
• Microsoft Internet Explorer (version 8 or higher) or Mozilla
Firefox (version 3.5.2 or higher). In the advanced connection
options, add the unit address to the address list. Do not use a
proxy server.
• Java platform (version 6 or higher). In the control panel,
deselect (uncheck) the option that allows storing tempo-
rary internet files and use a direct connection.
To access the PIC6 user interface, enter the IP address of the
unit in the address bar of the web browser. The IP address can
be viewed or changed from the PIC6 interface. For more infor-
mation on the web browser and Java platform configuration,
see the Diagnostics and Troubleshooting section.
General Interface Features
ICONS
Table 9 shows general interface icons.
Table 9 — Interface Icons
SCREENS
The Human Machine Interface includes the following screens:
• Home screen, which displays the main parameters
• Menu screens for navigation
• Data/configuration screens, which list the parameters by type
• Operating mode selection screen
• Password entry and language selection screen
• Parameter modification screen
• Time schedule screen
If the interface is not used for a long period, it goes into screen-
saver mode and displays a black screen. However, the control
is always active and the unit operating mode remains un-
changed. When the user presses the black screen, the Home
screen is displayed.
System Overview (Home) Screen
Figure 10 shows the system overview screen. Press a compo-
nent image to see current status. For details, see Status Display
Screens on page 15.
Messages
The Set Point screen, On/Off screen, User Login screen, and
Main Menu screens described in the next sections may display
status messages at the bottom of the screen. See Table 10.
Fig. 10 — System Overview (Home) Screen
Table 10 — Status Messages
ICON MEANING
Green: Indicates unit is running
Gray: Indicates unit is off
Home
Main menu
Indicates user is logged off
Indicates user is logged in
Gray: Indicates no alarm or alert is active
Red: Indicates alarm or alert
Back (not visible in main menu)
Previous and next screen
MESSAGE STATUS
COMMUNICATION FAILURE! Equipment controller did not respond while
reading the table content.
ACCESS DENIED! Equipment controller does not allow access to
one of the table data blocks.
LIMIT EXCEEDED! The value entered exceeds the table limits.
Save changes? Modifications have been made. The interface
waits to confirm exit; press Save or Cancel.
HIGHER FORCE IN EFFECT! Equipment controller rejected a Force or Auto
command because the interface force level is
lower than that of the equipment controller.
LEGEND
1—Home Screen Access Button
2—Main Menu Access Button
3—Globe Button
4—User Login Screen Access Button
5—Unit Start/Stop Access Button
6—Alarm Menu Access Button
7—Condenser Saturated Pressure and Temperature
8—VFD Status
9—Evaporator Saturated Pressure and Temperature
10 —Guide Vane 1 Position Percentage
11 —Motor Load Current Percentage
12 —Guide Vane 2 Position Percentage
13 —Evaporator Water Inlet and Outlet Temperature
14 —Second Stage Bearing Temp
15 —Refrigerant Pressure Differential
16 —First Stage Bearing Temp
17 —Condenser Water Inlet and Outlet Temperature
23456
1
7
8
9
1011
12
13
14
15
16
17

13
Set Point Screen
The Set Point screen displays the current set point table. See
Fig. 11. For more information about these settings, see the Set
Point section on page 18.
Fig. 11 — Set Point Screen
Unit Start/Stop Screen
The Unit Start/Stop screen allows the user to select the unit op-
erating mode.
For unit start-up, with the unit in Local Off mode, press the
gray Off icon to display the list of operating modes. Select
the required mode to start up the chiller. See Fig. 12.
Fig. 12 — Unit Start/Stop Screen
When a start-up mode is selected, a status screen displays the
progress of the start-up sequence (Fig. 13).
Fig. 13 — Start-Up Sequence Progress
To stop the unit, press the green On icon . Then press Con-
firm Stop to stop the unit, or press the Back icon to cancel the
stop and return to the previous screen. See Fig. 14.
Fig. 14 — Confirm Stop
User Login Screen
Use this screen to login or log off and to set interface language and
measurement system. There are three levels of password access:
• Basic access allows the user to view all data without a
password.
• User access gives the user the additional ability to view
and change many configuration settings, including set
points and schedules. The default User password is 1111.
• Service access can be granted through Carrier Smart Ser-
vice by an administrator. Password is good for 7 days and
gives access to all Service tables.
• Factory access (located under Service Login icon) allows
access to critical factory configuration settings and only
authorized users will have access to these menus using
Carrier Smart Service.
From the Home screen, touching the Globe icon displays
the Language and Units Selection screen. See Fig. 15.
Fig. 15 — User Login Screen — Language and Units
Selection
The Lock icon on the Home screen allows access to the pass-
word menu and displays current software version. See Fig. 16.
NOTE: The active language is bracketed by arrows.

14
Fig. 16 — User Login Screen — Password Menu
Main Menu Screen
To access the Main Menu screen, press the Main Menu icon
. Press the icons on the screen to access the appropriate ta-
ble or menu. Press the arrows at the bottom right corner, if
present, to navigate through pages of tables. The options
shown on the Main Menu screen depend on the user’s level of
access (see the section User Login Screen on page 13). Figures
17 and 18 shows the Main Menu screen as it appears for the
User level of access.
Fig. 17 — Main Menu Screen, Page 1 (User Access)
Fig. 18 — Main Menu Screen, Page 2 (User Access)
Configuration Screen
To access the Configuration menu, press the Configuration icon
on page 2 of the Main Menu (User, Service, or Factory ac-
cess level). The Configuration menu opens. Then press the Gen-
eral Configuration icon on the Configuration menu. Press
the arrows at the bottom right corner to navigate through pages.
See Fig. 19. (Certain configuration settings are available only for
Service or Factory access levels.) Refer to Appendix A, page 54,
for more information about Configuration options.
Fig. 19 — General Configuration Screen
After changing a value, press Return. The Save and Cancel
icons are displayed. Press the Save icon to save the changed
value. Figure 20 shows an example.
Fig. 20 — Saving a Change
(General Configuration)
Schedule Menu Screen
To access the Schedule menu screen, press on the Configura-
tion menu screen. Select Local Schedule, Ice Build Schedule, or
Network Schedule as applicable. Press the arrows at the bottom
right corner to navigate through the time periods. See Fig. 21.
Fig. 21 — Local Schedule Menu Screen

15
Status Display Screens
Figure 22 shows the system status overview (home) screen.
Press any component on the screen to see the status of that
component. Press the arrows at the bottom right corner to navi-
gate through the component status displays. Figures 23-29
show the component status displays.
Fig. 22 — System Overview (Home) Screen
Fig. 23 — Condenser Status
Fig. 24 — Evaporator Status
Fig. 25 — Envelope Control Status
Fig. 26 — Compressor Status
Fig. 27 — Motor Status
Fig. 28 — VFD Status

16
Fig. 29 — Purge Status
CONTROL OPERATION
Start-Stop Control
This function controls the chiller START-STOP command. The
four selectable control modes are as follows: LOCAL, LOCAL
SCHEDULE, REMOTE, or NETWORK. See Unit Start/Stop
Screen on page 13. Specific control sources are valid to start or
stop the chiller for each control mode.
LOCAL
When the control mode is LOCAL, the chiller can be started by
the “Local ON” button on the PIC6 interface screen, and can
be shut down by the Confirm Stop button on the screen or by
the EMSTOP software point.
LOCAL SCHEDULE
When the control mode is LOCAL SCHEDULE, the chiller
will be started automatically if the configurable local schedule
is Occupied. The chiller can be shut down by the unoccupied
schedule, the Stop button on the PIC6 interface screen, or by
the EMSTOP software point.
REMOTE
When the control mode is REMOTE, the chiller will be started
by the remote discrete input (REM_CON) located on the I/O
board. The chiller can be shut down by the remote discrete in-
put, the Stop button on the PIC6 interface screen, or by the
EMSTOP software point.
NETWORK
When the control mode is NETWORK, the chiller can be start-
ed and stopped by the CHIL_S_S and CHIL_OCC software
points, which are written by other equipment through network
commands and network schedule (both must be TRUE for
chiller to start). To shut down the chiller, use the EMSTOP
software point or stop using the HMI.
NOTE: There is a STOP OVERRIDE point in the GENUNIT ta-
ble. If this point is enabled the chiller cannot be started.
Compressor Run Status
Compressor run status is shown at the top of the system over-
view (home) screen. Table 11 lists chiller status numbers,
names, and descriptions.
Chiller Start-Up Sequence
PRE-START CHECK
Once start-up begins, the controller performs a series of pre-start
tests to verify that all pre-start alerts and safeties are within limits.
Progress is shown on the Startup Sequence screen (see Fig. 30).
This screen can be accessed by touching the mode title (top blue
bar) of the home screen. Table 12 lists pre-start alert and alarm
conditions.
The compressor RUN STATUS parameter on the default
screen line now reads PRESTART. If a test is not successful,
the start-up is delayed or aborted. If all tests are successful, the
chilled water pump relay energizes, and the main screen line
now reads STARTUP.
Table 11 — Compressor Run Status
Fig. 30 — Start-Up Sequence Screen
STATUS
NO.
STATUS
NAME DESCRIPTION
0 OFF STATSTOP is STOP, no alarm.
1 CTLTEST Controls Test is active.
2 PUMPDOWN Pumpdown is active.
3 LOCKOUT Lockout is active.
4 RECYCLE
Recycle shutdown completed on low load
in effect until the need for cooling resumes;
non-fault condition.
5 TRIPOUT Shutdown completed due to alarm fault
condition.
6 TIMEOUT
The controller is delaying the start
sequence until the Start to Start or Stop to
Start timers have elapsed.
7 PRESTART
The chiller is in the process of system
checking before energizing the compressor
motor.
8 STARTUP Normal start-up in progress.
9 AUTORST Auto Restart in progress.
10 RAMPING
Ramp loading in progress. The chiller has
started and is gradually increasing its load
to control electrical demand charges.
11 RUNNING
The chiller has completed ramp loading fol-
lowing start-up. Normal running mode, no
override or demand limit.
12 OVERRIDE Running with Override active.
13 DEMAND
Running with Demand Limit active. The chiller
is prevented from loading further because it
has reached an AVERAGE LOAD CUR-
RENT limit or a MOTOR KILOWATTS limit.
14 SHUTDOWN Compressor shutdown in progress.
15 FREECOOL Free Cooling in Progress
16 CONDFLSH Condenser Flush in Progress
(Note: Available for “Marine Option” only).

17
Table 12 — Pre-Start Alerts and Alarms
* Evap trip point = 33°F (0.6°C) (water) or EVAP REFRIG TRIPPOINT
(brine).
START-UP
One second after the successful pre-start check, the chilled wa-
ter and condenser water pump relays are energized.
Five seconds later, the control monitors the chilled water and
condenser water flow devices and waits until the WATER
FLOW VERIFY TIME (service-configured, default 5 minutes)
expires to confirm water flow.
After water flow is verified, the water temperature is compared to
CONTROL POINT + 1/2 CHILLED WATER DEADBAND. If
the temperature is less than or equal to this value, the control turns
off the condenser pump relay and goes into RECYCLE mode.
If the RECYCLE condition is not satisfied, the start-up se-
quence continues and checks the guide vane position. The
guide vanes are opened to the initial position specified with
GV1 Closure at Startup in the Option Configuration menu.
If an EC/HGBP or economizer damper valve is equipped and
enabled, the control checks that the position of these valves is
fully closed.
If the vanes and valves positions are verified and the refriger-
ant pump pressure difference is less than 2.5 psi (17.2 kPa), the
refrigerant pump relay is energized.
The control then waits the operator-configured verification time
(default 40 seconds) for the refrigerant pressure difference to reach
12 psi. After the refrigerant pressure is verified, the control waits
20 seconds for prelube, and after achieving and maintaining the
refrigerant pressure, the compressor start relay energizes to start
the compressor.
Chiller Shutdown Sequence
Chiller shutdown begins if any of the following occurs:
• Local OFF button is pressed
• A RECYCLE condition is present (see the previous section)
• The time schedule has gone into unoccupied mode when in
either Network or Local Schedule control mode
• The chiller protective limit has been reached and chiller is
in alarm
• The start/stop status (CHIL_S_S) is overridden to stop
from the network when in Network mode
If the chiller is normally shut down from running, a soft-stop
shutdown will be performed. The soft-stop feature closes the
guide vanes of the compressor automatically if a non-alarm
stop signal occurs before the compressor motor is deenergized.
Any time the compressor is directed to STOP (except in the
cases of a fault shutdown), the guide vanes are directed to close
and VFD will be commanded to minimum speed for a variable
speed compressor. The compressor shuts off when any of the
following is true:
• PERCENT LOAD CURRENT (%) drops below the SOFT
STOP AMPS THRESHOLD
• ACTUAL GUIDE VANE POSITION drops below 4%
• Four minutes have elapsed since the stop was initialized
When any of these conditions is true, the shutdown sequence
stops the compressor by deactivating the compressor start re-
lay. The guide vanes are then commanded to the fully closed
position. The refrigerant pump relay will be turned off after
120 seconds post-lube.
Finally, the chilled water/brine pump and condenser water
pump are shut down.
Refrigerant Lubrication Control
The lube sled assembly under the 19DV condenser barrel man-
ages the lubricating refrigerant supply to the compressor bear-
ings. As part of startup/shutdown, 19DV goes through the stages
identified in Table 13.
Essentially the evaporator and condenser control valves are po-
sitioned to charge the high side float chamber with liquid re-
frigerant from the cooler or to supply liquid refrigerant to the
bearings from the high side float chamber.
For startup the refrigerant pump delta difference must at least
be 8 psig (55.2 kPa).
If it is the first time that the unit is being started, then the con-
trols will perform a 30 minute pre-lubrication. Status flag for
this is found in the Quick Calibration menu.The refrigerant
pump relay is always ON when the compressor is running.
PRE-START ALERT CONDITION STATE NO. ALARM OR ALERT
STARTS IN 12 HOURS >= 8 100 Alert
CONDENSER PRESSURE >= COND PRESS OVERRIDE – 20 psi 102 Alert
Number of recycle restart in the last 4 hours is greater than 5 103 Alert
COMP BEARING TEMP >= COMP BEARING ALERT – 10°F (5.5°C) 230 Alarm
COMP MOTOR WINDING TEMP >= MOTOR TEMP OVERRIDE – 10°F (5.5°C) 231 Alarm
COMP DISCHARGE TEMP >= COMP DISCHARGE ALERT– 10°F (5.5°C) 232 Alarm
EVAP_SAT < Evap trip point* + EVAP OVERRIDE DELTA T
or
EVAP REFRIG LIQUID TEMP < Evap trip point* + EVAP OVERRIDE DELTA T
233 Alarm
ACTUAL LINE VOLTAGE <= UNDERVOLTAGE THRESHOLD 234 Alarm
ACTUAL LINE VOLTAGE >= OVERVOLTAGE THRESHOLD 235 Alarm
Guide vane 1 has not been calibrated successfully 236 Alarm
Prestart Failure - No Power Supply (If Water Verification Time has passed after Request To Start
has been sent and there has not been received a Permission To Start) 237 Alarm
Guide vane 2 has not been calibrated successfully 238 Alarm

18
NOTES:
1. Upon competition of post-lube the chiller is off and the sequence
can be started over.
2. Evaporator Control Valve:
Close = source refrigeration pump from high side float chamber
Open = source refrigeration pump from evaporator
3. Condenser Control Valve:
Close = refrigerant pump discharge to compressor bearings
Open = refrigerant pump discharge to high side float chamber
Control Points
SET POINT
The set point can be configured at the Setpoint menu (“USER”
access level).
The set point is determined by the heat/cool mode, EWT (en-
tering water temperature) option, and ice build option. See
Table 14.
Table 14 — Set Point Determination
NOTES:
1. The ice build option is disabled when heat/cool mode is set to
Heating.
2. When the ice build option is enabled and ice build is active, the
control point is the Ice Build Set Point and the controlled water tem-
perature is the leaving chilled water temperature.
CONTROL POINT TEMPERATURE
Capacity control is based on achieving and maintaining a control
point temperature, which is the sum of a valid set point (from the
SETPOINT screen) and a temperature reset value. In Cooling
mode, the control point temperature is equal to the set point plus
temperature reset. In Heating mode, the control point temperature
is equal to the set point minus temperature reset.
The control point can be viewed directly on the main screen or
the General Parameters menu.
TEMPERATURE RESET
Three types of chilled water or brine reset are available and can
be viewed or modified on the Reset Configuration screen.
The default screen indicates when the chilled water reset is ac-
tive. The control point Reset on the General Parameters screen
indicates the amount of reset.
To activate a reset type, access the Reset Configuration
(RESETCFG) screen and input all configuration informa-
tion for that reset type.
Reset Type 1: 4 to 20 mA Temperature Reset
Reset Type 1 is an automatic reset utilizing a 4 to 20 mA analog
input signal provided from any external sensor, controller, or
other device which is appropriately configured. For this type,
Degrees Reset At 20 mA is configured in the RESETCFG table.
Reset Type 2: Remote Temperature Reset
Reset Type 2 is an automatic water temperature reset based on
a remote temperature sensor input signal. This function can be
accessed by setting the following configurations:
1. Configure the remote temperature at which no reset occurs
(Remote temp
 NO RESET).
2. Configure the remote temperature at which full reset
occurs (Remote temp
 FULL RESET).
3. Enter the amount of reset (Deg Reset Water DT Full).
Reset Type 3: Controlled Water Temp Delta Reset
Reset Type 3 is an automatic controlled water temperature re-
set based on heat exchanger temperature difference. This func-
tion can be accessed by setting the following configurations:
1. Configure the controlled water temperature delta T at which
no reset occurs (Controlled Water DELTA T
 NO RESET).
2. Configure the controlled water temperature delta T at
which full reset occurs (Controlled Water DELTA T

FULL RESET).
3. Enter the amount of reset (Deg Reset Water DT Full).
CAPACITY CONTROL
Capacity control provides chilled or condenser water tempera-
ture control by modulating the position of the inlet guide vane 1
and VFD speed for variable speed compressors.
For 19DV when increased capacity is needed, the control will
first try to increase IGV TARGET POSITION if it has not
reached the travel limit; if the travel limit has been reached, the
control increases VFD TARGET SPEED. If decreased capacity
is needed, the control first tries to decrease VFD TARGET
SPEED if it has not reached the minimum VFD speed; if the
minimum VFD speed has been reached, the control decreases
IGV TARGET POSITION instead. See Fig. 31.
Table 13 — Lube Assembly Control Valve (CV)
STATUS CONTROL VALVE DESCRIPTION
EVAPORATOR CONDENSER
CHILLER OFF Close Close Chiller is off - a start is to be initiated to change state.
PRE-START Close Open Refrigerant pump turns on if pump differential pressure is less than 5 psig - if differential
pressure higher Alarm 285 will be displayed.
PRE-CHARGE Close Open
Objective is the charge the high side float with refrigerant. If high side float chamber level switch is
not closed the refrigerant will be pumped from the evaporator to the high side float chamber until
the high side float chamber level switch is satisfied. If level switch is not closed after 10 minutes
alert 163 will be active and startup will stop. Once high side float chamber switch is satisfied the
pre-charge process pumping liquid to the high side float chamber will continue for 1 minute.
PRE-LUBE Open Close
Upon completion of the pre-charge state the controls will verify that the pump refrigerant
differential pressure is greater than the limit (typically 8 psig). If not alarm 285 will be
activated. Pre-lube will provide refrigerant to the compressor bearings from the high side float
chamber. Its duration is 10-20 seconds.
COMPRESSOR RUN Open Close Refrigerant pump is continuously on and refrigerant is provided to compressor bearings from
high side float chamber.
POST-LUBE Close Close
Upon compressor stop a post-lube cycle of 30 seconds is completed before the refrigerant
pump is stopped. During post-lube the bearings are supplied with refrigerant from the
evaporator.
EWT
CONTROL
OPTION
HEAT/COOL MODE
COOLING HEATING
Disabled Cooling LCW Set Point Heating LCDW Set Point
Enabled Cooling ECW Set Point Heating ECDW Set Point

19
Fig. 31 — Guide Vane Position and VFD Speed
From the compressor relay closed point to the end of ramp
loading, the VFD TARGET SPEED is the configured VFD
start-up speed. When the chiller is running normally, the capac-
ity control determines whether and how much to change VFD
TARGET SPEED. When the chiller is in the shut-down pro-
cess, VFD TARGET SPEED will be the minimum VFD speed.
NOTE: If the VFD option is set to NO VFD, or the compressor re-
lay is not closed, VFD TARGET SPEED will be 0.
The guide vane position is determined by the Capacity Control
function under normal conditions and other functions in abnormal
conditions, which include capacity inhibit request or capacity de-
crease request. The guide vane actuator is driven by comparing the
guide vane target position and the actual position. Guide vane po-
sition is limited to a value between zero and IGV Travel Limit,
which is configured from the Service Configuration menu. When
the chiller is shutting down or off, the guide vane is always driven
to zero during normal shutdown. Guide Vane 2 is forced based on
linear interpolation of set points based on Guide Vane 1 position
(see 19DV Configuration).
RAMP LOADING
The ramp loading control slows the rate at which the compressor
loads up. This control can prevent the compressor from loading up
during the short period of time when the chiller is started and the
chilled water loop has to be brought down to CONTROL POINT
(Setpoint Table). Ramp loading helps reduce electrical demand
charges by slowly bringing the chilled water to CONTROL
POINT. The total power draw during this period remains almost
unchanged. If the power outage lasts for more than 3 hours, then
Temperature Ramp Loading will be used regardless of user con-
figuration and the minimum loading rate (1°F/min) will be used.
Two methods of ramp loading are available: temperature ramp
loading and motor load ramp loading.
Temperature Ramp Loading
Temperature ramp loading limits the rate at which the controlled
water temperature decreases for cooling and increases for heat-
ing during ramping by reducing on cooling mode or increasing
in heating mode the PULLDOWN SET POINT (Maintenance
Menu
 Capacity) at the configured rate, until the pulldown set
point is less than the cooling mode control point or greater than
the heating mode control point. The PULLDOWN RAMP
TYPE (Configuration Menu
 General Configuration) is
configured to 0 for temperature ramp loading.
Motor Load Ramp Loading
Motor load ramp loading limits the rate at which either the load
current percentage or motor kilowatt percentage increases by
incrementing the ramp demand limit at the configured rate.
The PULLDOWN RAMP TYPE (Configuration Menu

General Configuration) is configured to 1 for motor load ramp
loading.
If DEMAND LIMIT SOURCE (Configuration Menu
 Gen-
eral Configuration) is set to AMPS, then PERCENT LOAD
CURRENT is used for motor load ramp loading. If DEMAND
LIMIT SOURCE is set to kW, then MOTOR PERCENT
KILOWATTS is used for motor load ramp loading.
The motor load ramp loading algorithm shall be deactivated
when the Ramp Demand Limit is greater than or equal to the
ACTIVE DEMAND LIMIT (General Parameters). It is also
deactivated when Ramp Demand Limit is greater than or equal
to 80%. There will be a one-minute delay for the compressor to
be uploaded to target load (ramping load target 80% or AC-
TIVE DEMAND LIMIT if less than 80%) after ramping load
demand limit is set to 80% (or ACTIVE DEMAND LIMIT if
less than 80%).
GUIDE VANES AT MAX.
MODULATE VFD
GUIDE VANES
VFD AT START-UP SPEED,
MODULATE GUIDE VANES
VFD
STARTUP:
VFD TO START-UP SPEED,
GUIDE VANES CLOSED
MAX.
START
MIN.
VFD % SPEED
0TRAVEL LIMIT 100
GUIDE VANES % POSITION

20
SURGE CORRECTION CONTROL
There are two stages for surge correction: envelope control
(surge prevention) and surge protection.
Envelope Control
A surge condition occurs when the lift becomes so high that the
gas flow across the impeller reverses. This condition can even-
tually cause compressor damage. The surge prevention algo-
rithm notifies the operator that chiller operating conditions are
marginal and to take action, such as lowering entering con-
denser water temperature, to help prevent compressor damage.
If a high sound condition occurs at low guide vane position, the
EC/HGBP (Envelope Control/Hot Gas Bypass) valve is used to
decrease the sound level. The envelope control algorithm is an
operator-configurable feature that can determine if lift condi-
tions are too high for the compressor and then take corrective
action. High efficiency mode or low noise mode can be select-
ed. Lift is defined as the difference between the saturated tem-
perature at the impeller eye and at the impeller discharge. The
maximum lift a particular impeller wheel can perform varies
with the gas flow across the impeller and the size of the wheel.
If Actual Lift is higher than reference lift, a capacity inhibit
signal will be sent. If Actual Lift is higher than reference lift
plus Envelope High Deadband, a capacity decrease signal will
be sent. If Actual Lift is lower than reference lift minus Enve-
lope Low Deadband, these 2 signals will be canceled. Capacity
Control will respond to these 2 signals and make correction on
IGV1 TARGET POSITION, VFD TARGET SPEED, and EC/
HGBP actuator. To improve system performance SURGE
PROFILE OFFSET will be incremented by 1 if no surge pre-
vention has been active in the past 5 minutes. The Reference
Lift will subtract the SURGE PROFILE OFFSET prior to com-
paring to Actual Lift.
Surge Protection
The Surge Protection algorithm will run after SURGE DELAY
TIME has elapsed when compressor has been commanded to
turn on. It compares the present PERCENT LOAD CURRENT
value with the previous value once every second. If the differ-
ence exceeds the maximum AMPS change value (SURGE
DELTA % AMPS + [PERCENT LINE CURRENT / 10]), an
incidence of surge has occurred, and the surge protection signal
will be sent.
When an incidence of surge determined in this manner has oc-
curred, the SURGE COUNTS will be incremented by one. On
receiving the surge protection signal, Capacity Control will
make corrections on IGV1 TARGET POSITION, VFD TAR-
GET SPEED, and EC/HGBP actuator. When correction is in
effect, Surge Protection Count will increase by 1 when a com-
mand for either IGV decrease, VFD speed increase, or EC/
HGBP actuator activation is required for correction. Guide
vane movement will be inhibited for 1 minute after surge pro-
tection ends.
Chiller will do 259 Alarm shutdown under the following
conditions.
• If Surge Protection Counts exceed 20 within a Surge Time
Period. Note that if VFD, then VFD target speed must
equal max before this alarm is activated.
• If IGV, VFD, and HGBP cannot be further adjusted for
surge protection when Surge Protection Counts exceed 4
within a Surge Time Period.
If IGV, VFD, and HGBP control cannot correct the problem,
the chiller will initiate a shutdown alarm when the surge count
is greater than 4.
ENVELOPE/HOT GAS BYPASS (HGBP) CONTROL
This function is used to artificially load the chiller and keep it
running under low load conditions or to prevent surge condi-
tions. Since this also reduces the performance of the machine,
EC/HGBP Control is a user-selectable option.
The EC/HGBP control valve is a modulating type controlled
by a 4 to 20 mA signal.
Envelope/hot gas bypass operation has three different modes
when installed (hgbp_opt > 0) and enabled (hgbp_sel > 0):
• Envelope control and surge protection — Each compressor
has unique lift characteristics that can be plotted to deter-
mine performance. The controller will determine operating
conditions that could result in compressor surge and acti-
vate the bypass valve to prevent surge until the chiller op-
erating parameters are in a safe area on the curve where the
valve may be closed again.
• Envelope (HGBP) low load operation — In this condition,
the valve will be opened to prevent a recycle shutdown
from occurring. The valve will remain open until this min-
imal loading condition has passed and there is no surge
condition present.
• Combination for envelope control and surge correction, as
well as low load operation — When this option is selected,
both EC for envelope control/surge protection and EC for
low load operation will be performed. Surge protection
will take higher priority if both conditions are satisfied.
DEMAND LIMIT
The PIC6 controls provide a feature for limiting AVERAGE
LOAD CURRENT or MOTOR KILOWATTS by limiting ca-
pacity via guide vane control/VFD control. The limit may be
applied in two ways. The first is called ACTIVE DEMAND
LIMIT, which is equal to a BASE DEMAND LIMIT value (set
in the SETPOINT screen, default value 100%). ACTIVE DE-
MAND LIMIT may also be forced to be different from BASE
DEMAND LIMIT by manually overriding (forcing) the value
via a CCN network device. If the DEMAND LIMIT SOURCE
exceeds the ACTIVE DEMAND LIMIT by 5% or less, capaci-
ty will be inhibited. If the DEMAND LIMIT SOURCE ex-
ceeds the ACTIVE DEMAND LIMIT by more than 5%, ca-
pacity will be decreased.
Alternatively, the limit may be applied by AUTO DEMAND
LIMIT INPUT, an optional 4 to 20 mA input. This demand
limit control option (4 to 20 mA DEMAND LIMIT TYPE) is
externally controlled by a 4 to 20 mA signal. The option is set
up on the Configuration Menu
 GENERAL CONFIGURA-
TION screen. When enabled, 4 mA will set ACTIVE DE-
MAND LIMIT to 100% of the DEMAND LIMIT SOURCE
(regardless of the value of BASE DEMAND LIMIT), and 20
mA will set ACTIVE DEMAND LIMIT to the value config-
ured for DEMAND LIMIT AT 20 mA in the Configuration
Menu
 SERVICE PARAMETERS screen.
OVERRIDE CONTROL
Capacity overrides can prevent some safety shutdowns caused
by exceeding the motor amperage limit, evaporator refrigerant
low temperature safety limit, motor high temperature safety
limit, and condenser high pressure limit. In these cases there
are two stages of capacity control:
1. When the value of interest crosses the first stage set point
into the override region, the capacity is prevented from
increasing further, and the status line on the PIC6 control-
ler indicates the reason for the override. Normal capacity
control operation is restored when the value crosses back
over the first stage set point, leaving the override region.
2. When the value of interest is in the override region and
further crosses the second stage set point, the capacity is
decreased until the value meets the override termination
condition. The PIC6 controls resume normal capacity con-
trol operation after the override termination condition has
been satisfied. (In the case of high discharge superheat,
there is an intermediate stage.)
Table 15 summarizes these override parameters.