York YCAV0267E Owner's manual

MODELS YCAV0267-0527, 60 HZ
STYLE A
(290-515 TONS)
AIR-COOLED SCREW LIQUID CHILLERS
E/V HIGH EFFICIENCY AND S/P STANDARD EFFICIENCY
50075
AIR-COOLED SCREW
LIQUID CHILLERS
INSTALLATION, OPERATION, MAINTENANCE Supersedes 201.21-NM3 (315) Form 201.21-NM3 (616)
035-20994-000
R134a
Issue Date:
June 30, 2016

2JOHNSON CONTROLS
FORM 201.21-NM3 (616)
This equipment is a relatively complicated apparatus.
During rigging, installation, operation, maintenance,
or service, individuals may be exposed to certain com-
ponents or conditions including, but not limited to:
heavy objects, refrigerants, materials under pressure,
rotating components, and both high and low voltage.
Each of these items has the potential, if misused or
handled improperly, to cause bodily injury or death. It
is the obligation and responsibility of rigging, instal-
lation, and operating/service personnel to identify and
recognize these inherent hazards, protect themselves,
and proceed safely in completing their tasks. Failure
to comply with any of these requirements could result
in serious damage to the equipment and the property in
IMPORTANT!
READ BEFORE PROCEEDING!
GENERAL SAFETY GUIDELINES
which it is situated, as well as severe personal injury or
death to themselves and people at the site.
This document is intended for use by owner-authorized
rigging, installation, and operating/service personnel. It
is expected that these individuals possess independent
training that will enable them to perform their assigned
tasks properly and safely. It is essential that, prior to
performing any task on this equipment, this individual
shall have read and understood the on-product labels,
this document and any referenced materials. This in-
dividual shall also be familiar with and comply with
all applicable industry and governmental standards and
regulations pertaining to the task in question.
SAFETY SYMBOLS
The following symbols are used in this document to alert the reader to specific situations:
Indicates a possible hazardous situation
which will result in death or serious injury
if proper care is not taken.
Indicates a potentially hazardous situa-
tion which will result in possible injuries
or damage to equipment if proper care is
not taken.
Identies a hazard which could lead to
damage to the machine, damage to other
equipment and/or environmental pollu-
tion if proper care is not taken or instruc-
tions and are not followed.
Highlights additional information useful
to the technician in completing the work
being performed properly.
External wiring, unless specied as an optional connection in the manufacturer’s product line, is not
to be connected inside the control cabinet. Devices such as relays, switches, transducers and controls
and any external wiring must not be installed inside the micro panel. All wiring must be in accor-
dance with Johnson Controls’ published specications and must be performed only by a qualied
electrician. Johnson Controls will NOT be responsible for damage/problems resulting from improper
connections to the controls or application of improper control signals. Failure to follow this warn-
ing will void the manufacturer’s warranty and cause serious damage to property or personal injury.

3
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
The Control/VSD Cabinet contains lethal High AC and DC voltages. Before
performing service inside the cabinet, remove the AC supply feeding the chiller
and verify using a non-contact voltage sensor.
The DC Voltage on the VSD DC Bus will take 5 minutes to bleed off, after AC
power is removed. Always check the DC Bus Voltage with a Voltmeter to assure
the capacitor charge has bled off before working on the system.
• NEVER short out the DC Bus to discharge the lter capacitors.
• NEVER place loose tools, debris, or any objects inside the Control Panel/VSD
Cabinet.
• NEVER allow the Control Panel VSD Cabinet doors to remain open if there is
a potential for rain to enter the panel. Keep doors closed and assure all latches
are engaged on each door unless the unit is being serviced.
• ALWAYS lockout the disconnect supplying AC to the chiller.
• The 1L Line Inductor will reach operating temperatures of over 300° F. DO
NOT open panel doors during operation. Assure the inductor is cool whenever
working near the inductor with power off.
WARNING!
CHANGEABILITY OF THIS DOCUMENT
In complying with Johnson Controls’ policy for con-
tinuous product improvement, the information con-
tained in this document is subject to change without
notice. Johnson Controls makes no commitment to
update or provide current information automatically
to the manual or product owner. Updated manuals, if
applicable, can be obtained by contacting the nearest
Johnson Controls Service office or accessing the John-
son Controls QuickLIT website at http://cgproducts.
johnsoncontrols.com.
It is the responsibility of rigging, lifting, and operating/
service personnel to verify the applicability of these
documents to the equipment. If there is any question
regarding the applicability of these documents, rig-
ging, lifting, and operating/service personnel should
verify whether the equipment has been modified and
if current literature is available from the owner of the
equipment prior to performing any work on the chiller.
CHANGE BARS
Revisions made to this document are indicated with a
line along the left or right hand column in the area the
revision was made. These revisions are to technical in-
formation and any other changes in spelling, grammar
or formatting are not included.

4JOHNSON CONTROLS
FORM 201.21-NM3 (616)
TABLE OF CONTENTS
SECTION 1 - GENERAL CHILLER
INFORMATION & SAFETY
INTRODUCTION ......................................................9
WARRANTY..............................................................9
SAFETY......................................................................9
Standards for Safety................................................9
RESPONSIBILITY FOR SAFETY..........................10
ABOUT THIS MANUAL.........................................10
MISUSE OF EQUIPMENT......................................10
Suitability for Application ....................................10
Structural Support.................................................10
Mechanical Strength.............................................10
General Access .....................................................10
Pressure Systems ..................................................11
Electrical...............................................................11
Rotating Parts .......................................................11
Sharp Edges ..........................................................11
Refrigerant & Oils ................................................11
High Temperature & Pressure Cleaning ...............11
Emergency Shutdown...........................................11
SECTION 2 - PRODUCT DESCRIPTION
INTRODUCTION ....................................................12
General System Description .................................12
Compressor...........................................................13
Evaporator ............................................................14
Condensor.............................................................14
Flash Tank Feed / Drain Valve..............................15
Oil Separator / Oil System....................................15
Relief Valves.........................................................15
Oil Cooling ...........................................................16
Capacity Controls .................................................16
Power and Control Panel ......................................16
Microprocessor & VSD Controls .........................16
Display..................................................................17
Keypad..................................................................17
Unit Switch...........................................................17
Variable Speed Drive (VSD) ................................18
ACCESSORIES & OPTIONS..................................19
Single Point Circuit Breaker.................................19
Building Automation System (BAS) Interface.....19
Condensor Coil Protection....................................19
DX COOLER OPTIONS..........................................20
SERVICE VALVE OPTION .....................................20
UNIT ENCLOSURES ..............................................20
FANS.........................................................................20
SOUND REDUCTION OPTIONS...........................20
VIBRATION ISOLATION .......................................20
UNIT NOMENCLATURE .......................................21
PRODUCT IDENTIFICATION NUMBER .............22
SECTION 3 - RIGGING, HANDLING AND
STORAGE
DELIVERY AND STORAGE ..................................26
INSPECTION ...........................................................26
MOVING THE CHILLER........................................26
Lifting Weights .....................................................26
UNIT RIGGING .......................................................27
SECTION 4 - INSTALLATION
LOCATION REQUIREMENTS...............................29
OUTDOOR INSTALLATION..................................29
INDOOR INSTALLATION......................................29
LOCATION CLEARANCES ...................................30
VIBRATION ISOLATORS ......................................30
Installation ............................................................30
SHIPPING BRACES................................................30
CHILLED LIQUID PIPING.....................................30
General Requirements ..........................................30
WATER TREATMENT.............................................32
CONNECTION TYPES & SIZES............................32
COOLER CONNECTIONS .....................................32
Option Flanges......................................................32
REFRIGERANT RELIEF VALVE PIPING .............33
DUCTWORK CONNECTION ................................33
General Requirements ..........................................33
ELECTRICAL CONNECTION ...............................33
POWER WIRING.....................................................34
115 VAC CONTROL SUPPLY TRANSFORMER ..34
CONTROL PANEL WIRING...................................34
VOLTS FREE CONTACTS .....................................35
Chilled Liquid Pump Starter.................................35
Run Contact ..........................................................35
Alarm Contact.......................................................35
SYSTEM INPUTS....................................................35
Flow Switch..........................................................35
Remote Run/Stop..................................................35
Optional Remote Setpoint Offset Temp. ..............35
Optional Remote Setpoint Offset Sound Limit ....35

5
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
SECTION 5 - COMMISSIONING
PREPARATION........................................................36
PREPARATION - GENERAL..................................36
Inspection..............................................................36
Refrigerant Charge ...............................................36
Service and Oil Line Valves .................................36
Compressor Oil.....................................................36
Fans.......................................................................36
Isolation / Protection.............................................36
Control Panel ........................................................36
Power Connections...............................................37
Grounding.............................................................37
Water System ........................................................37
Flow Switch..........................................................37
Temperature Sensor(s)..........................................37
Programmed Options............................................38
Programmed Settings............................................38
Date & Time .........................................................38
Start / Stop ............................................................38
Setpoint & Remote Offset ....................................38
FIRST TIME STARTUP...........................................38
Interlocks ..............................................................38
Unit Switch...........................................................38
Start-Up ................................................................38
Oil Pressure...........................................................38
Refrigerant Flow...................................................39
Loading.................................................................39
Condensor & Fan Rotation...................................39
Suction Super Heat ...............................................39
Sub-Cooling..........................................................39
General Operation.................................................39
SECTION 6 - TECHNICAL DATA
WATER PRESSURE DROP CHARTS ....................40
GLYCOL CORRECTION FACTORS......................42
WATER TEMP. AND FLOWS .................................43
PHYSICAL DATA....................................................44
OPERATING LIMITATIONS AND
SOUND POWER .................................................48
ELECTRICAL DATA - COMPR. WIRING .............49
ELECTRICAL NOTES ............................................60
WIRING DIAGRAMS - 3 COMPRESSOR.............62
WIRING DIAGRAMS - 4 COMPRESSOR.............74
DIMENSIONS..........................................................90
TECHNICAL DATA (CLEARANCES) .................156
WEIGHT DISTRIBUTION &
ISOLATOR MOUNTING .................................158
ISOLATOR MOUNTING POSITIONS .................159
SEISMIC ISOLATOR INSTALLATION ...............163
NEOPRENE ISOLATOR POSITION ....................164
1" DEFLECTION ISOLATOR INSTALLATION..165
REFRIGERANT FLOW DIAGRAM.....................167
PROCESS & INSTRUMENTATION
DIAGRAM .........................................................168
COMPONENT LOCATIONS ................................169
EQUIPMENT START-UP CHECK SHEET...........188
Unit Checks (NO power)....................................188
Panel Checks
(Power ON-both system switches OFF).............190
Programmed Values............................................191
Chilled Liquid Setpoint ......................................191
Date/Time, Daily Schedule, & Clock Jumper ....191
Initial Start-Up....................................................192
Check Subcooling & Superheat..........................192
Leak Checking....................................................193
CHILLER ELECTRONIC COMPONENTS..........194
Keypad................................................................194
Display................................................................195
Chiller Control Board .........................................196
Relay Output Boards ..........................................197
VSD (Variable Speed Drive) ..............................197
AC to DC Rectier .............................................197
SCR Trigger Board .............................................198
DC Link Filter ....................................................198
1L Line Inductor .................................................199
AC to DC Inverter ..............................................199
Laminated Bus Structure ....................................199
VSD Logic Board ...............................................200
Control Panel to VSD Communications.............200
IGBT Gate Driver Boards...................................201
Current Transformers..........................................201
DV/DT Output Suppression Network ................202
Flash Tank Feed/Drain Valve Controller ............202
DC Bus Voltage Isolation Board.........................203
Chiller Circuit Breaker .......................................203
Autotransformer..................................................203
CHILLER CONFIGURATION JUMPERS............204
Number of Compr. Conguration Jumpers ........204
VSD LOGIC TO CHILLER MICROPROCESSOR
BOARD RS-485 COMMUNICATION
CONFIGURATION JUMPERS .........................204
MAX VSD FREQUENCY .....................................205
TABLE OF CONTENTS (CONT’D)

6JOHNSON CONTROLS
FORM 201.21-NM3 (616)
SECTION 7 - OPERATION
OPERATING CONTROLS ....................................206
BASIC OPERATING SEQUENCE........................208
NUMBER OF COMPRESSORS TO START ........209
General................................................................209
Standard IPLV.....................................................209
Optional Optimized IPLV...................................209
MINIMUM VSD COMPRESSOR
START/STOP FREQUENCY.............................210
Minimum VSD Start Frequency.........................210
Minimum VSD Run Frequency..........................210
ACCELERATION/DECELERATION RATE
WHEN STARTING & STOPPING
COMPRESSORS ...............................................211
VSD Acceleration/ Deceleration Rates...............211
STANDARD IPLV CAPACITY CONTROL........212
Fuzzy Logic Control...........................................213
Hot Water Starts..................................................214
Lag Compressor Operation in Load Limiting ....214
OPTIONAL IPLV CAPACITY CONTROL...........215
Fuzzy Logic ........................................................216
Hot Water Starts..................................................217
LOAD LIMITING CONTROL ..............................218
FLASH TANK DRAIN/FEED VALVE
CONTROLLER ......................................................221
Valve Controller & Control Algorithm ..............221
ECONOMIZER CONTROL...................................224
CONDENSER FAN CONTROL ............................224
VSD TEMPERATURE CONTROL/FAN
CONTROL OPERATION.......................................227
REMOTE TEMPERATURE RESET CONTROL..229
Local Current Limit Control..............................229
Pulldown Current Limit Setpoint .......................229
REMOTE CURRENT LIMIT RESET ..................230
Sound Limit Controls .........................................232
SECTION 8 - MICROPANEL
VSD OPERATION & CONTROLS .......................234
VSD Cooling and Cooling Loop ........................236
VSD SAFETIES .....................................................240
IGBT Gate Driver (Hardware) Fault ..................243
Power Supply (Hardware) Fault.........................245
UNIT WARNINGS .................................................248
UNIT SAFETIES....................................................252
SYSTEM SAFETIES..............................................254
STATUS KEY.........................................................260
UNIT DATA KEY...................................................264
SYSTEM DATA KEY.............................................266
VSD DATA KEY ....................................................270
OPERATING HOURS & START KEYS ...............272
HISTORY KEY.......................................................273
Unit Data.............................................................274
VSD Data............................................................275
System Data........................................................276
Compressor Operating Hours & Starts...............278
Chilled Liquid & Cooling Setpoints..................278
Options................................................................278
Program Values...................................................279
SETPOINTS KEY ..................................................281
PROGRAM KEY....................................................283
OPTIONS KEY.......................................................286
DATE/TIME & SCHEDULE KEY ........................290
Date/Time Key....................................................290
Schedule Key......................................................291
Unit Operating Schedule ....................................292
Sound Limit Schedule ........................................293
MANUAL OVERRIDE KEY.................................294
PRINT KEY............................................................295
Operating Data Printout......................................296
History Data Printout..........................................297
SERVICE KEY .......................................................298
SYSTEM SWITCHES KEY...................................304
SERIAL NUMBER PROGRAMMING .................305
ENABLING OPTIMIZED HIGH IPLV MODE ....307
UNIT SETUP MODE .............................................308
DEFAULT PROGRAMMABLE VALUES ............310
SERIAL PORT CONNECTIONS...........................311
ANALOG INPUT CONNECTIONS......................310
DIGITAL INPUT CONNECTIONS.......................314
ANALOG OUTPUT CONNECTIONS..................316
DIGITAL OUTPUT CONNECTIONS...................318
ISN COMMUNICATIONS
& TRANSMITTED DATA .....................................320
TABLE OF CONTENTS (CONT’D)

7
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
SECTION 9 - MAINTENANCE
R-134A CONVERSION TABLES .........................328
MAINTENANCE ...................................................329
General Requirements ........................................329
MAINTENANCE REQUIREMENTS ...................330
TROUBLESHOOTING GUIDE ............................332
EVACUATING A SYSTEM ...................................334
WARRANTY POLICY...........................................335
New Equipment ..................................................335
Reconditioned or Replacement Materials...........335
All Warranties are VIOD if.................................335
CHILLED LIQUID & SUCTION TEMP
SENSOR INPUT VOLTAGE TABLE....................336
OUTSIDE AIR TEMP SENSOR INPUT
VOLTAGE TABLE.................................................337
PRESSURE TRANSDUCER OUTPUT
VOLTAGE TABLE.................................................338
MOTOR TEMPERATURE SENSOR
RESISTANCE TABLE ...........................................339
COMPRESSOR MOTOR OVERLOAD SETTINGS
& MAXIMUM VSD FREQUENCY..................340
PRINTER WIRING ................................................341
Okidata 184.........................................................342
Weigh-Tronix IMP Model 2600 .........................342
Seiko ...................................................................342
OPERATING LOG .................................................343
Site and Chiller Info ...........................................343
Programmed Values............................................343
Unit Operating Temperature, Pressures,
& Currents .......................................................344
System Operating Conditions.............................345
Water System Conditions ...................................346
Condensor Conditions ........................................346
RECOMMENDED SPARE PARTS .......................347
LIST OF TABLES
Table 1 - Compressors and the Appropriate Jumper
Positions ..................................................204
Table 2 - VSD Logic Board Address Jumper..........204
Table 3 - Maximum Frequency Jumper ..................205
Table 4 - Fuzzy Logic Loading/Unloading
vs. Error...................................................214
Table 5 - Fuzzy Logic Loading/Unloading
vs. Error...................................................217
Table 6 - Current Load Limiting/Unloading...........218
Table 7 - Discharge Pressure Load Limiting/
Unloading .................................................218
Table 8 - Suction Pressure Load Limiting/
Unloading .................................................219
Table 9 - VSD Internal Ambient Load Limiting/
Unloading ................................................219
Table 10 - VSD Baseplate Temperature Load
Limiting/Unloading...............................220
Table 11 - Fan Stages & Corresponding Outputs....225
Table 12 - VSD Operating Display Parameters ......239
Table 13 - Low Differential Oil Pressure Cutout ...256
Table 14 - Start Inhibit Sensor Thresholds..............258
Table 15 - Sensor Min./Max. Outputs.....................268
Table 16 - Setpoint Limits.......................................282
Table 17 - Programmable Operating Parameters ....285
Table 18 - Printout Types ........................................295
Table 19 - Unit Setup Programmable Values..........308
Table 20 - Serial Port Connections .........................311
Table 21 - Analog Input Connections .....................312
Table 22 - Digital Input Connections......................314
Table 23 - Analog Output Connections...................316
Table 24 - Digital Output Connections ...................318
Table 25 - Mustang Chiller YORK Talk
Control Data ..........................................320
Table 26 - DXST/ISN Transmitted Data.................321
Table 27 - Fault Inhibit Codes ................................325
Table 28 - Operational Status Codes.......................327
Table 29 - R-134a Pressure to Saturated
Temperature Conversion .......................328
Table 30 - Temperature Input Voltage Sensor.........336
Table 31 - Outside Air Temperature Input Voltage .337
Table 32 - Pressure Transducer Input Voltage.........338
Table 33 - Motor Temperature Sensor Resistance ..339
Table 34 - Compressor Motor Overload Settings &
Max. VSD Frequency............................340

8JOHNSON CONTROLS
FORM 201.21-NM3 (616)
General Chiller Information & Safety
Fig 1 - PWM Current Waveform ..............................18
Fig 2 - PWM Voltage Waveform...............................18
Fig 3 - Pipework Arrangement..................................32
Fig 4 - Victaulic Groove............................................32
Fig 5 - Flange Attachment.........................................32
Fig 6 - Single Point Power Supply Connection
W/Circuit Breaker Protection (3 Compr) ......49
Fig 7 - Single Point Power Supply Connection
W/Terminal Block (3 Compr) .......................49
Fig 8 - Single Point Power Supply Connection
W/Circuit Breaker Protection (4 Compr) ......50
Fig 9 - Single Point Power Supply Connection
W/Terminal Block (4 Compr) .......................50
Fig 10 - Multi-Point Power Supply Connection
W/Circuit Breaker Protection (4 Compr) ....49
Fig 11 - Multi-Point Power Supply Connection
W/Terminal Block (4 Compr) .....................49
Fig 12 - Sample Printout Supplied in the Isolator
Package & Chiller Panel
Literature Packet .......................................158
Fig 13 - Refrigerant Flow Diagram ........................167
Fig 14 - Processes and Instrumentation ..................168
Fig 15 - Component Locations ...............................169
Fig 16 - Control and VSD Cabinet Locations.........170
Fig 17 - Chiller Control Board, Relay Boards,
Microgateway, and Optional
Circuit Breaker ..........................................171
Fig 18 - Chiller Control Board, Relay Boards, and
Microgateway............................................172
Fig 19 - VSD Logic Board......................................173
Fig 20 - VSD Logic Board......................................173
Fig 21 - Power Components ...................................175
Fig 22 - Power Components ...................................175
Fig 23 - Fan Contactors...........................................177
Fig 24 - VSD Components......................................178
Fig 25 - VSD Components......................................179
Fig 26 - VSD Components......................................180
Fig 27 - VSD Components......................................181
Fig 28 - Inverter Power Components......................182
Fig 29 - Inverter Power Components......................183
Fig 30 - Inverter Power Components......................184
Fig 31 - Inverter Power Components......................184
Fig 32 - Glycol Pump & Fill Tube Locations .........185
Fig 33 - Glycol Piping & Fill Tube Locations ........186
Fig 34 - Compressor Components ..........................187
Fig 35 - Chiller Control (Cooling) Range...............208
Fig 36 - Number of Compressors to Start...............209
Fig 37 - Minimum VSD Start Frequency ...............210
Fig 38 - Minimum VSD Run ..................................210
Fig 39 - LED Locations ..........................................222
Fig 40 - Power, Comms LED's ...............................223
Fig 41 - Power, Comms & System Open/Close
LED's.........................................................223
Fig 42 - Standard IPLV Fan Control.......................226
Fig 43 - High IPLV Fan Control .............................226
Fig 44 - Print Cable Chiller to Serial Printer ..........341
LIST OF FIGURES

9
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
1
GENERAL CHILLER INFORMATION & SAFETY
INTRODUCTION
YORK YCAV0267-0527 chillers are manufactured to
the highest design and construction standards to ensure
high performance, reliability and adaptability to all types
of air conditioning installations.
The unit is intended for cooling water or glycol solu-
tions and is not suitable for purposes other than those
specied in this manual.
Rigging and lifting should only be done by a profes-
sional rigger in accordance with a written rigging and
lifting plan. The most appropriate rigging and lifting
method will depend on job specific factors, such as the
rigging equipment available and site needs. Therefore,
a professional rigger must determine the rigging and
lifting method to be used, and it is beyond the scope of
this manual to specify rigging and lifting details.
This manual contains all the information required for
correct installation and commissioning of the unit, to-
gether with operating and maintenance instructions. The
manuals should be read thoroughly before attempting
to operate or service the unit.
All procedures detailed in the manuals, including in-
stallation, commissioning and maintenance tasks must
only be performed by suitably trained and qualied
personnel.
The manufacturer will not be liable for any injury or
damage caused by incorrect installation, commission-
ing, operation or maintenance resulting from a failure
to follow the procedures and instructions detailed in
the manuals.
WARRANTY
YORK warrants all equipment and materials against
defects in workmanship and materials for a period of
eighteen months from date of shipment, unless labor
or extended warranty has been purchased as part of the
contract.
The warranty is limited to parts only replacement and
shipping of any faulty part, or sub-assembly, which has
failed due to poor quality or manufacturing errors. All
claims must be supported by evidence that the failure
has occurred within the warranty period, and that the
unit has been operated within the designed parameters
specied.
All warranty claims must specify the unit model, serial
number, order number and run hours/starts. Model and
serial number information is printed on the unit identi-
cation plate.
The unit warranty will be void if any modication to the
unit is carried out without prior written approval from
YORK International.
For warranty purposes, the following conditions must
be satised:
• The initial start of the unit must be carried out by
trained personnel from an Authorized YORK Ser-
vice Center. See Commissioning (Page 36).
• Only genuine YORK approved spare parts, oils,
coolants, and refrigerants must be used. Recom-
mendations on spare parts stocking can be found
on Page 345.
• All the scheduled maintenance operations detailed
in this manual must be performed at the specied
times by suitably trained and qualied personnel.
See Maintenance Section, Page 326-344.
•Failure to satisfy any of these conditions will automati-
cally void the warranty. See Warranty Policy (Page 333).
SAFETY
Standards for Safety
YCAV chillers are designed and built within an ISO
9002 accredited design and manufacturing organization.
The chillers comply with the applicable sections of the
following Standards and Codes:
• ANSI/ASHRAE Standard 15, Safety Code for Me-
chanical Refrigeration.
• ANSI/NFPA Standard 70, National Electrical Code
(N.E.C.).
• ASME Boiler and Pressure Vessel Code, Section
VIII Division 1.
• ARI Standard 550/590-98, Water Chilling Packages
Using the Vapor Compression Cycle.
• ASHRAE 90.1 Energy Standard for Building Except
Low-Rise Residential Buildings.
• ARI 370 Sound Rating of Large Outdoor Refrigera-
tion and Air Conditioning Equipment.
In addition, the chillers conform to Underwriters Labo-
ratories (U.L.) for construction of chillers and provide
U.L./cU.L. Listing Label.

10 JOHNSON CONTROLS
FORM 201.21-NM3 (616)
PRODUCT DESCRIPTION
RESPONSIBILITY FOR SAFETY
Every care has been taken in the design and manufac-
ture of the unit to ensure compliance with the safety
requirements listed above. However, the individual
rigging, lifting, maintaining, operating or working on
any machinery is primarily responsible for:
• Personal safety, safety of other personnel, and
the machinery.
• Correct utilization of the machinery in ac-
cordance with the procedures detailed in the
manuals.
ABOUT THIS MANUAL
The following terms are used in this document to alert
the reader to areas of potential hazard.
A WARNING is given in this document to identify a
hazard, which could lead to personal injury. Usually an
instruction will be given, together with a brief explana-
tion and the possible result of ignoring the instruction.
A CAUTION identies a hazard which could lead to
damage to the machine, damage to other equipment
and/or environmental pollution. Usually an instruction
will be given, together with a brief explanation and the
possible result of ignoring the instruction.
A NOTE is used to highlight additional information,
which may be helpful to you but where there are no
special safety implications.
The contents of this manual include suggested best
working practices and procedures. These are issued for
guidance only, and they do not take precedence over
the above stated individual responsibility and/or local
safety regulations.
This manual and any other document supplied with the
unit are the property of YORK which reserves all rights.
They may not be reproduced, in whole or in part, without
prior written authorization from an authorized YORK
representative.
MISUSE OF EQUIPMENT
Suitability for Application
The unit is intended for cooling water or glycol solu-
tions and is not suitable for purposes other than those
specied in these instructions. Any use of the equipment
other than its intended use, or operation of the equipment
contrary to the relevant procedures may result in injury
to the operator, or damage to the equipment.
The unit must not be operated outside the design param-
eters specied in this manual.
Structural Support
Structural support of the unit must be provided as in-
dicated in these instructions. Failure to provide proper
support may result in injury to the operator, or damage
to the equipment and/or building.
Mechanical Strength
The unit is not designed to withstand loads or stresses
from adjacent equipment, pipework or structures. Ad-
ditional components must not be mounted on the unit.
Any such extraneous loads may cause structural failure
and may result in injury to the operator, or damage to
the equipment.
General Access
There are a number of areas and features, which may
be a hazard and potentially cause injury when working
on the unit unless suitable safety precautions are taken.
It is important to ensure access to the unit is restricted
to suitably qualied persons who are familiar with the
potential hazards and precautions necessary for safe
operation and maintenance of equipment containing
high temperatures, pressures and voltages.

11
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
2
Pressure Systems
The unit contains refrigerant vapor and liquid under
pressure, release of which can be a danger and cause
injury. The user should ensure that care is taken during
installation, operation and maintenance to avoid dam-
age to the pressure system. No attempt should be made
to gain access to the component parts of the pressure
system other than by suitably trained and qualied
personnel.
Electrical
The unit must be grounded. No installation or main-
tenance work should be attempted on the electrical
equipment without rst switching power OFF, isolat-
ing and locking-off the power supply. Servicing and
maintenance on live equipment must not be attempted.
No attempt should be made to gain access to the control
panel or electrical enclosures during normal operation
of the unit.
Rotating Parts
Fan guards must be tted at all times and not removed
unless the power supply has been isolated. If ductwork is
to be tted, requiring the wire fan guards to be removed,
alternative safety measures must be taken to protect
against the risk of injury from rotating fans.
Sharp Edges
The ns on the air-cooled condenser coils have sharp
metal edges. Reasonable care should be taken when
working in contact with the coils to avoid the risk of
minor abrasions and lacerations. The use of gloves is
recommended.
Frame rails, brakes, and other components may also have
sharp edges. Reasonable care should be taken when
working in contact with any components to avoid risk
of minor abrasions and lacerations.
Refrigerants and Oils
Refrigerants and oils used in the unit are generally non-
toxic, non-ammable and non-corrosive, and pose no
special safety hazards. Use of gloves and safety glasses
is, however, recommended when working on the unit.
The build up of refrigerant vapor, from a leak for ex-
ample, does pose a risk of asphyxiation in conned or
enclosed spaces and attention should be given to good
ventilation.
Use only the refrigerant specifically designated for the
unit. Any other type of refrigerant may cause damage
to the equipment and will void the warranty.
High Temperature and Pressure Cleaning
High temperature and pressure cleaning methods (e.g.
steam cleaning) should not be used on any part of the
pressure system as this may cause operation of the pres-
sure relief device(s). Detergents and solvents, which may
cause corrosion, should also be avoided.
Emergency Shutdown
In case of emergency, the control panel is tted with
a Unit Switch to stop the unit in an emergency. When
operated, it removes the low voltage 120 VAC electri-
cal supply from the inverter system, thus shutting down
the unit.

12 JOHNSON CONTROLS
FORM 201.21-NM3 (616)
Product Description
PRODUCT DESCRIPTION
INTRODUCTION
YORK YCAV R134a chillers are designed for water
or glycol cooling. All units are designed to be located
outside on the roof of a building or at ground level.
The units are completely assembled with all intercon-
necting refrigerant piping and internal wiring, ready for
eld installation.
Prior to delivery, the unit is pressure tested, evacuated,
and fully charged with refrigerant and oil in each of the
two independent refrigerant circuits. After assembly,
an operational test is performed with water owing
through the cooler to ensure that each refrigerant circuit
operates correctly.
The unit structure is manufactured from heavy gauge,
galvanized steel. Many external structural parts are
coated with “Champagne” baked-on enamel powder
paint. This provides a nish which, when subjected to
ASTM B117, 1000 hour, 5% salt spray conditions, shows
breakdown of less than 1/8” either side of a scribed line
(equivalent to ASTM D1654 rating of “6”).
All exposed power wiring is routed through liquid-tight,
non-metallic conduit.
General System Description
The Latitude (YCAV) Air Cooled Chiller line combines
the best of modern screw compressor design with the
latest technology in variable speed drives. The result is
superior control and efciency in real world conditions.
The VSD enables slowing the speed of the compressor to
match the load on the system resulting in precise chilled
liquid control, minimized sound, maximum energy ef-
ciency, and reduced cost of ownership. The VSD also
provides soft starts with no electrical inrush. The lack
of heat build-up on start also enables required off time
between starts to be reduced to a period of 2 minutes.
The YCAV Air-Cooled Screw Chiller utilizes many
components, which are the same or nearly the same as
a standard screw chiller of a similar size. This includes
modular frame rails, condenser, fans, compressors and
evaporator.
The chiller consists of 3 or 4 screw compressors in a
corresponding number of separate refrigerant circuits,
a single shell and tube DX evaporator, an air-cooled
condenser, ash tanks, drain/feed valves, oil separators,
and compressor mufers. Oil separators utilize no mov-
ing parts and are rated for a 405 PSIG design working
pressure. Oil cooling is accomplished by routing oil
from the oil separator through several rows of tubes in
the air cooled condenser.
50074d

13
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
2
An integral liquid cooled, transistorized, PWM, Variable
Speed Drive (VSD) is controlled by the chiller micro-
processor control panel to start/stop, select compressors
to run, and select compressor speed. Power Factor is
95% at part or full load.
The chiller microprocessor communicates with the VSD
Logic Board via a 3-wire RS-485 opto coupled data link.
The VSD Logic Board runs the number of compressors
required to meet the load and the compressors to the
speed requested by the chiller microprocessor.
The basic system control architecture is shown in the
diagram below:
The chiller is designed to operate in ambient tempera-
tures of 0°F to 125°F (-18°C to 52°C). Capacity control
is capable of reducing chiller capacity to 10% of full
load without the need for hot gas bypass.
Compressor
The direct drive semi-hermetic rotary twin-screw MTS
compressor is designed for industrial refrigeration ap-
plications and ensures high operational efciencies and
reliable performance. Capacity control is achieved by
stepless VSD speed changes. No slide valve is required.
Smooth capacity control is achieved between 10%
and 100% of chiller capacity in most operating condi-
tions. The compressor is a positive displacement type
characterized by two helically grooved rotors, which
are manufactured from forged steel. The 4 pole motor
operates at speeds up to 6000 RPM to direct drive the
male rotor, which in turn drives the female rotor on a
light lm of oil.
CHILLER CONTROL SYSTEM
INPUTS
COMMUNICATIONS
OUTPUTS
VSD
MOTOR
CONTROL
PANEL
Pressure Transducers
Temperature Sensors
Level Sensor
Switches
Liquid Flow
High Pressure
Start/Stop
Customer Supplied
Contacts
(Chiller Control
Board)
Microprocessor
User Interface
Display
&
Keypad
Building Automation
Printer
Modem
VSD Logic Board
SCR Trigger Board
Power Components
PWM (Speed Control)
(Relay Output
Board)
Solenoids
Contactors
Alarm
Pump
Compressor Heater
Run Status
Evap Heater
Refrigerant gas is injected into the void created by the
un-meshing of the ve lobed male and seven lobed fe-
male rotor. Further meshing of the rotors closes the rotor
threads to the suction port and progressively compresses
the gas in an axial direction to the discharge port. The
gas is compressed in volume and increased in pressure
before exiting at a designed volume at the discharge end
of the rotor casing. Since the intake and discharge cycles
overlap, a resulting smooth ow of gas is maintained.
The rotors are housed in a cast iron compressor hous-
ing precision machined to provide optimal clearances
for the rotors. Contact between the male and female
rotor is primarily rolling on a contact band on each of
the rotor’s pitch circle. This results in virtually no rotor
wear and increased reliability, a trademark of the screw
compressor.
The MTS compressor incorporates a complete anti-
friction bearing design for reduced power input and
increased reliability. Separated, cylindrical, roller bear-
ings handle radial loads. Angular-contact ball bearings
handle axial loads. Together they maintain accurate rotor
positioning at all pressure ratios, thereby minimizing
leakage and maintaining efciency.
LD10478
LD10481
LD10482

14 JOHNSON CONTROLS
FORM 201.21-NM3 (616)
Product Description
Motor cooling is provided by suction gas from the
evaporator owing across the motor. Redundant over-
load protection is provided using both internal thermistor
and current overload protection on all three phases.
The MTS compressor is lubricated by removing oil from
the refrigerant using an external oil separator. The pres-
surized oil is then cooled in the condenser coils and piped
back to the compressor through a removable 0.005”
mesh screen oil lter to provide compressor lubrication.
The cast iron compressor housing design working pres-
sure is 450 PSIG (31 bar). Each chiller receives a 300
PSIG (21 bar) low side and a 450 PSIG (31 bar) high side
factory test. A 350 Watt (115-1-60 Hz) cartridge heater
is located in the compressor. The heater is temperature
activated to prevent refrigerant condensation.
The following items are also included:
• Acoustically tuned, external discharge mufer to
minimize noise, while optimizing ow for maxi-
mum performance.
• Discharge shutoff valve.
• Rain-tight terminal box.
• Suction gas screen within the compressor hous-
ing.
Evaporator
The system uses a high-efciency Shell and Tube type
Direct Expansion Evaporator. Each of the three or four
refrigerant circuits consists of two (2) passes with the
chilled liquid circulating back and forth across the tubes
from one end to the other.
The design working pressure of the cooler on the shell
side is 150 PSIG (10 bar), and 235 PSIG (16 bar) for
the tube (refrigerant) side. The evaporator is constructed
and tested in accordance with applicable sections of the
ASME Pressure Vessel Code, Section VII, Division (1).
Waterside exempt per paragraph U-1, c, (6).
The water bafes are fabricated from galvanized steel
to resist corrosion. Removable heads are provided for
access to internally enhanced, seamless, copper tubes.
Water vent and drain connections are included.
The cooler is equipped with a thermostatically con-
trolled heater for protection to -20°F (-29°C) ambient
and insulated with 3/4” (19 mm) exible closed-cell
insulation.
The water nozzles are provided with grooves for
mechanical couplings and should be insulated by the
contractor after pipe installation.
A 300 PSIG (20.7 bar) waterside design working pres-
sure option is available.
2 compressor chillers utilize a typical 2-pass “E” type
evaporator with liquid inlets and suction outlets at the
same end. Entering chilled liquid enters the refrigerant
liquid inlet end of the cooler and leaving chilled liquid
exits at the opposite end.
3 and 4 compressor chillers utilize a single pass “J”
type evaporator with liquid inlets at one end and suction
outlets at the opposite end. Entering chilled liquid is
split and half ow enters at each end of the evaporator
with leaving chilled liquid exiting in the center of the
evaporator. “J” type evaporators have fewer, longer
tubes than a comparable “E” type. This results in a
smaller diameter, longer shell. Water ow rate internally
in the evaporator is ½ of the total loop ow rate since
the ow is split between two inlets. This results in a
low evaporator water pressure drop.
Condenser
The n and tube condenser coils are manufactured
from seamless, internally enhanced, high-condensing
coefcient, corrosion-resistant copper tubes arranged
in staggered rows and mechanically expanded into cor-
rosion resistant aluminum alloy ns with full height n
collars. The condensor has a design working pressure
of 450 PSIG (31 bar).
Multiple, standard low sound, high efciency, TEAO
motor driven fans move air through the coils. They are
dynamically and statically balanced, direct drive with
corrosion-resistant glass ber reinforced composite
blades molded into low-noise, full airfoil cross sec-
tions, providing vertical air discharge from extended
orices for efciency and low sound. Fans or pairs of
fans are located in a separate compartments separated
by "V" panels to prevent cross ow during fan cycling.
Guards of heavy-gauge, PVC-coated galvanized steel
are provided.
The standard fan motors are high-efciency, direct drive,
6-pole, 3-phase, Class- “F,” current overload protected,
totally enclosed (TEAO) type with double-sealed, per-
manently lubricated ball bearings.

15
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
2
Flash Tank Feed Valve/Drain Valves
A Flash Tank is tted to both refrigerant circuits. The
Flash Tank is a shell type refrigerant reservoir designed
to sustain 2 phase refrigerant. The purpose of the Flash
Tank is to increase the efciency of the system. A
portion of the liquid fed into the Flash Tank gases off,
cooling the remaining liquid in the tank another 25-35°F.
Both liquid and gas exist in the ash tank. The refriger-
ant gas in the ash tank is fed to the economizer port on
the compressor at a point on the rotors approximately
1.7X suction when the economizer solenoid is activated.
The liquid in the tank is fed to the evaporator.
The vapor feed to the economizer port of the compres-
sor is at an intermediate pressure between discharge
and suction (1.7 x suction) and therefore little energy
is required to pump it back through the compressor to
condenser pressure. This results in a very small loss to
system efciency.
The design working pressure of the ash tank is 450
PSIG (31 bar). The Drain and Feed Valves on the ash
tank are activated on start-up. The Feed Valve on the
Flash Tank acts like a liquid line solenoid, but also func-
tions to control the liquid level in the ash tank. The
Drain Valve functions similar to an electronic expan-
sion valve (EEV). The Drain Valve controls refriger-
ant ow to the evaporator based on suction superheat.
Both valves are stepper motor valves. An economizer
solenoid is placed between the ashtank and the econo-
mizer port of the compressor. The economizer solenoid
valve is generally activated at speeds above 90-120 Hz,
depending upon a number of other factors.
Both valves are controlled by 2 phase drive signals from
a stand-alone controller in the Control Cabinet. Signals
from sensors such as suction pressure and temperature
are sent to the Chiller Control Board, which in turn sends
control signals to the Drain and Feed Valve Controller.
The control algorithm in the Chiller Control Board will
attempt to control the liquid level in the ash tank to
35% on the level sensor and the system will fault if the
ash tank level exceeds 87.5%.
During operation, it will be noted the ash tank level
will typically remain between 30-40% level when the
economizer solenoid is ON. The economizer solenoid
valve will typically be on most of the time. When the
economizer solenoid is OFF, the liquid level will vary
greatly as the Drain and Feed Valves directly affect the
level as they open and close.
Oil Separator/Oil System
The external oil separators, with no moving parts and
designed for minimum oil carry-over, are mounted in
the discharge line of the compressor. The high pressure
discharge gas is forced around a 90 degree bend. Oil is
forced to the outside of the separator through centrifugal
action and captured on wire mesh where it drains to the
bottom of the oil separator and is then forced into the
condensor.
The oil (YORK “L” oil – a POE oil used for all refriger-
ant applications), ows from the oil separator, through
the condenser where it is cooled, and back into the com-
pressor through a replaceable 0.5 micron oil lter at high
pressure. This high pressure “oil injection” forces the oil
into the compressor, where it is fed to the bearings and
rotors for lubrication. After lubricating the bearings, it is
injected through orices on a closed thread near the suc-
tion end of the rotors. The oil is automatically injected
because of the pressure difference between the discharge
pressure and the reduced pressure at the suction end of
the rotors. This lubricates the rotors as well as provides
an oil seal against leakage around the rotors to ensure
refrigerant compression efciency.
The oil also provides cooling by transferring much of
the heat of compression from the gas to the oil, keeping
discharge temperatures down and reducing the chance
for oil breakdown. Oil injected into the rotor cage
ows into the rotors at a point about 1.2x suction. This
ensures that a required minimum differential of at least
30 PSID exists between discharge and 1.2x suction, to
force oil into the rotor case. A minimum of 10 PSID
(0.6 bar) is all that is required to ensure protection of
the compressor. The oil pressure safety is monitored as
the difference between suction pressure and the pressure
of the oil entering the rotor case.
Maximum working pressure of the oil separator is 450
PSIG (31 bar). Oil level should be above the midpoint
of the “lower” oil sight glass when the compressor is
running. Oil level should not be above the top of the
“upper” sight glass.
Relief Valves
Two relief valves are installed in each refrigerant circuit.
A 325 PSIG relief valve is located on each Flash Tank
and a 250 PSIG relief valve is located on the suction
line of the compressor near the evaporator.

16 JOHNSON CONTROLS
FORM 201.21-NM3 (616)
Product Description
Oil Cooling
Oil cooling is provided by routing oil from the oil sepa-
rator through several of the top rows of the condenser
coils and back to the compressor.
Capacity Control
When cooling is needed, one or more compressors,
as determined by the system microprocessor based on
deviation from setpoint, will start at minimum speed
with low inrush current. Variable speed operation of
the compressor reduces the capacity and allows smooth
balancing of the compressor capacity with the cooling
load.
Capacity control is accomplished by varying the number
of compressors and the speed of the compressors with
the VSD to promote stable, smooth, and precise load-
ing/unloading.
Hot Gas Bypass is not required with VSD control of
the compressors.
The chiller is available with Standard IPLV or High IPLV
software (EPROM). High IPLV software optimizes the
performance of the chiller capacity and fan controls.
High IPLV chillers also require additional factory
programming.
Power and Control Panel
All controls and the VSD are factory-wired and function
tested. The panel enclosures are designed to NEMA 3R
(IP65) rating and are manufactured from powder-painted
steel with hinged, latched, and gasket sealed outer doors
with wind struts for safer servicing.
The Power and Micro Control Panels are combined into
a single control/power cabinet and include Compressor
VSD Controls, Chiller Microprocessor Controls, Fan
Controls, and all other chiller controls.
The Display and Keypad are accessible through an
access door without opening the main doors to the
electrical cabinet.
Each Power Compartment Contains
Incoming single point power is standard utilizing either
a lockable circuit breaker or terminal block, 115VAC
control transformer, VSD, fan contactors, ON/OFF unit
switch, microcomputer keypad and display, Chiller Con-
trol and VSD Logic boards, 1 or 2 SCR trigger control
boards and relay boards.
Current transformers sense each phase of motor current,
and send corresponding signals to the Chiller Logic
Board. Current monitoring protects the compressor
motors from damage due to: low motor current, high
motor current, short circuit current, single phasing, and
compressor overload.
Short Circuit Withstand Rating of the chiller electrical
enclosure is 30,000 Amps for standard terminal block
connection. Ratings are in accordance with UL508C.
A Circuit Breaker Option can be added to increase the
Short Circuit Withstand Rating to 200/230V = 100,000
Amps, 380/460 V = 65,000 Amps, and 575V = 42,000
Amps.
Microprocessor and VSD Controls
Microprocessors on the Chiller Control Board and
VSD Logic Board control starting, stopping, loading,
unloading, safeties, and chilled liquid temperature
control. Chilled liquid control decisions are a function
of temperature deviation from setpoint and the rate of
change of temperature.
The standard controls include: brine chilling, thermal
storage, run signal contacts, unit alarm contacts, chilled
liquid pump control, automatic reset after power fail-
ure, automatic system optimization to match operating
conditions.
Remote cycling, optional current limiting, optional
temperature setpoint reset, and optional remote sound
limit can be accomplished by connecting user-supplied
signals to the microprocessor.
Unit operating software is stored in non-volatile
memory. Field programmed setpoints are retained in
lithium battery backed real time clock (RTC) memory
for 10 years.

17
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
2
Display
The display consists of a liquid crystal 2 line by 40
characters per line display, with backlighting for outdoor
viewing of operating parameters and program points.
Parameters are displayed in 5 languages in either Eng-
lish (°F and PSIG) or Metric (°C and Bars) units, and for
each circuit, the following items can be displayed:
• Entering and leaving chilled liquid, and ambient
temperature.
• Day, date and time. Daily start/stop times. Holiday
and Manual Override status.
• Compressor operating hours and starts. Automatic or
manual lead/lag. Lead compressor identication.
• Run permissive status. Compressor run status.
• Anti-recycle timers.
• System suction (and suction superheat), discharge
(and discharge superheat), and oil pressures and
temperatures.
• Percent full load compressor motor current and
average motor current. Compressor motor speed
(frequency).
• Cutout status and setpoints for: supply chilled liquid
temperature, low suction pressure, high discharge
pressure and temperature, high oil temperature, low
ambient, and low leaving liquid temperature.
• Unloading limit setpoints for high discharge pres-
sure and compressor motor current.
• Status of: evaporator heater, condenser fans, load/
unload timers, and chilled water pump.
• “Out of range” message.
• Up to 10 fault shutdown histories.
Keypad
An operator keypad allows complete control of the
system from a central location. The keypad utilizes
an overlay to allow use in 5 languages. The keypad is
a color-coded, 36 button, sealed keypad with keys for
Display, Entry, Setpoints, Clock, Print, Program, Unit
ON/OFF and other functions. Details on a few of the
keys follow.
Status – Allows viewing present unit or system status
displayed by the microprocessor.
Entry – Numeric keypad and supporting keys used to
conrm Setpoint changes, cancel inputs, advance day,
and change AM/PM.
Setpoints – For setting chilled liquid temperature,
chilled liquid range, remote reset temperature range.
Date/Time – Used to set time, daily or holiday start/stop
schedule, manual override for servicing, and sound
limiting schedule.
Print – Used to display or print operating data or sys-
tem fault shutdown history for last ten faults. Printouts
are generated through an RS-232 port via a separate
printer.
Program – For setting low leaving liquid temperature
cutout, average motor current limit, and pulldown de-
mand limit.
Displays are also provided for programming low am-
bient cutout, low suction pressure cutout, superheat
setpoint, etc., under the PROGRAM key.
Unit Switch
A master unit switch allows activation or de-activation
of the chiller system. Separate system switches for con-
trolling each system are provided as part of the chiller
control panel keypad.

18 JOHNSON CONTROLS
FORM 201.21-NM3 (616)
PRODUCT DESCRIPTION
The power section of the drive is composed of four
major blocks consisting of an AC to DC rectier section
with accompanying pre-charge circuit, a DC link lter
section, a three phase DC to AC inverter section, and
an output suppression network.
The AC to DC rectier utilizes a semi-converter formed
by the connection of three SCR/diode modules (1SCR-
3SCR) in a three phase bridge conguration. The mod-
ules are mounted on a liquid cooled heatsink. Use of the
semi-converter conguration permits implementation
of a separate pre-charge circuit to limit the ow of cur-
rent into the DC link lter capacitors when the drive is
switched on and it also provides a fast disconnect from
the power mains when the drive is switched off. When
the drive is turned off, the SCRs in the semiconverter
remain in a non-conducting mode and the DC link lter
capacitors remain uncharged. When the drive is com-
manded to run, the DC link lter capacitors are slowly
charged via the semi-converter. The SCR’s are then
gated fully on.
Three power fuses (1FU - 3FU), an optional circuit
breaker (1SW) and a standard 5% impedance minimum
3 phase line reactor connect the AC to DC converter to
the incoming power. Very fast semiconductor power
fuses are utilized to ensure that the SCR/diode module
packages do not rupture if a catastrophic failure were to
occur on the DC link. The SCR Trigger board provides
the gating pulses for the SCR’s as commanded by the
VSD Logic board.
The DC Link lter section of the drive consists of a
group of electrolytic lter capacitors (C1-C6). This ca-
pacitor bank effectively smooths the ripple voltage from
the AC to DC rectier while simultaneously providing a
large energy reservoir for use by the DC to AC inverter
section of the drive. In order to achieve the required
voltage capability for the capacitor portion of the lter,
lter capacitor “banks” are formed by connecting two
groups of parallel capacitors in series to form a capaci-
tor “bank”. In order to assure an equal sharing of the
voltage between the series connected capacitors and to
provide a discharge means for the capacitor bank when
the VSD is powered off, “bleeder” resistors (1RES and
2RES) are connected across the capacitor banks.
The DC to AC inverter section of the VSD serves to
convert the rectied and ltered DC back to AC at the
magnitude and frequency commanded by the VSD Logic
board. The inverter section is actually composed of two
to four identical inverter output phase assemblies. These
assemblies are in turn composed of 3 pairs of Insulated
FIG. 2 - PWM VOLTAGE WAVEFORM LD10480
Variable Speed Drive (VSD)
The VSD (variable speed drive) is a liquid cooled,
transistorized, PWM inverter, which provides speed
control to vary the speed of 2, 3 or 4 compressor motors.
The VSD changes the duration of the voltage pulses
supplied to the motor to enable control of compressor
speed to match the system load. A PWM generator, on
the VSD Logic Board, with a switching frequency of
3125 Hz modulates the voltage signal to provide a rela-
tively constant V/F ratio. In some cases, the V/F ratio
is slightly modied to provide additional torque to the
motor. Sample 3 phase current waveforms are shown
in FIG. 1 to show the sinusoidal characteristics of the
current drawn by the compressor motors.
FIG. 1 - PWM CURRENT WAVEFORM
LD10479
A Sample PWM voltage waveforms is shown in FIG.
2. The pulses near the sides of the rectangular groups
of waves are notably narrower, representing the lower
voltage of a sinusoidal waveform as it rises or falls from
the “0” crossing.

19
JOHNSON CONTROLS
FORM 201.21-NM3 (616)
2
Gate Bipolar Transistor (IGBT) modules mounted to a
liquid cooled heatsink, and a IGBT Gate Driver Board,
which provides the On and Off gating pulses to the
IGBT’s as determined by the VSD Logic board. In
order to minimize the parasitic inductance between the
IGBT’s and the capacitor banks, copper plates, which
electrically connect the capacitors to one another and to
the IGBT’s are connected together using a “laminated
bus” structure.
This “laminated bus” structure is a actually composed of
a pair of copper bus plates with a thin sheet of insulating
material acting as the separator/insulator. The “lami-
nated bus” structure forms a parasitic capacitor, which
acts as a small valued capacitor, effectively canceling
the parasitic inductance of the bus bars themselves. To
further cancel the parasitic inductances, a series of small
lm capacitors are connected between the positive and
negative plates of the DC link.
The VSD output suppression network is composed of
a series of capacitors and resistors connected in a three
phase delta conguration. The parameters of the sup-
pression network components are chosen to work in
unison with the parasitic inductance of the DC to AC
inverter sections in order to simultaneously limit both the
rate of change of voltage and the peak voltage applied to
the motor windings. By limiting the peak voltage to the
motor windings, as well as the rate-of-change of motor
voltage, we can avoid problems commonly associated
with PWM motor drives, such as stator-winding end-turn
failures and electrical uting of motor bearings.
The VSD is cooled by a propylene glycol cooling
loop. The loop utilizes a glycol pump, which pumps
glycol through the VSD heatsinks to cool the power
components. The glycol is then circulated through the
condenser to reject the heat from the VSD. The cooled
glycol is then circulated back through the loop.
Various ancillary sensors and boards are used to send
information back to the VSD Logic board. Each IGBT
Power Module within the DC to AC inverter section con-
tains a thermistor heatsink temperature sensor to provide
temperature information to the VSD logic board. The
Bus Isolator board utilizes three resistors on the board
to provide a “safe” impedance (resistance) between the
DC link lter capacitors located on the output phase
bank assemblies and the VSD logic board. It provides
the means to sense the positive, midpoint and negative
connection points of the VSD’s DC link without apply-
ing high voltage to the VSD Logic Board. A Current
Transformer is included on each output phase assembly
to provide motor current information to the VSD logic
board.
ACCESSORIES AND OPTIONS
Single Point Circuit Breaker
A single-point supply circuit with factory provided
circuit breaker protection with lockable external handle
located in the panel.
Building Automation System (BAS) Interface
Provides a means to reset the leaving chilled liquid
temperature or percent full load amps (current limiting)
from a BAS Interface.
The chiller microprocessor board will accept a 4 to
20mA or 0 to 10VDC input from an ISN or BAS.
The chiller is also capable of accepting an RS-485 com-
munications link through the Microgateway.
Condenser Coil Protection
The standard condenser coils have aluminum ns, cop-
per tubes, and galvanized steel supports for generally
adequate corrosion resistance. However, these materials
are not adequate for all environments.
The following options provide added protection:
Black n condenser coils – Condenser coils con-
structed using black epoxy-coated aluminum n stock
for corrosion-resistance for typical seashore locations
(not directly exposed to salt spray).
Copper n condenser coils – Coils constructed with
corrosion-resistant copper ns. Not recommended in
areas where units may be exposed to acid rain.
Epoxy Coated Condenser Coils – Completed
condenser coil assemblies are covered with a cured
epoxy coating. Probably the most suitable selection
for seashore locations where salt spray may come into
contact with the ns, and other corrosive applications
except: strong alkalis, oxidizers, and wet bromine,
chlorine, and uorine in concentrations greater than
100 PPM.

20 JOHNSON CONTROLS
FORM 201.21-NM3 (616)
PRODUCT DESCRIPTION
DX COOLER OPTIONS
300 PSIG (21 bar) Waterside Design Working Pressure
– The DX cooler waterside is designed and constructed
for 300 PSIG (21 bar) working pressure.
(Factory-mounted)
1-1/2” (38 mm) Insulation – Double-thickness insulation
provided for enhanced efciency.
Flange Accessory – Consists of raised face anges to
convert grooved water nozzles to anged cooler connec-
tions. Includes companion anges for eld mounting.
Remote DX Cooler – Includes the main condensing unit
less the cooler, refrigerant and liquid line devices. The
insulated cooler and eld accessory kits per refrigerant
circuit are supplied separately. The condensing unit is
shipped with a dry nitrogen holding charge and the cooler
is shipped with a dry nitrogen holding charge.
Flow Switch Accessory – Johnson Controls model
F61MG-1C Vapor-proof SPDT, NEMA 4X switch, 150
PSIG (10 bar) DWP, -20°F to 250°F (-29°C to 121°C),
with 1” NPT (IPS) connection for upright mounting in
horizontal pipe or equivalent. A ow switch must be eld-
installed with each unit. A 300PSIG (20.7 bar) optional
ow switch is available.
SERVICE VALVE OPTION
Suction Service Valve – Provides a suction and econo-
mizer service valve on each refrigerant circuit.
UNIT ENCLOSURES
Wire Enclosure – Heavy-gauge welded wire mesh
guards mounted on the exterior of the unit (Factory- or
eld-mounted).
Louvered Panels and Wired Guards – Louvered pan-
els mounted over the exterior condenser coil faces, and
heavy-gauge welded wire mesh guards mounted around
the bottom of the unit (Factory- or eld-mounted).
Louvered Panels (Condenser Coils Only) – Louvered
panels are mounted over the exterior condenser coil faces
on the sides of the unit to visually screen and protect the
coils (Factory- or eld-mounted).
Louvered Panels (Full Unit) enclosure – Louvered
panels over condenser coils and around the bottom of
the unit (Factory- or eld-mounted).
FANS
High Static Fans: Fans and motors suitable for High
External Static conditions to 100 Pa.
SOUND REDUCTION OPTIONS
Silent Night – This option allows speed limiting of
the compressors remotely or locally to reduce acoustic
noise. As speed is limited, fewer condenser fans are
needed for cooling, reducing noise.
Ultra Quiet Fans – Reduced RPM fan motors and
alternative fan selection for low noise applications.
Compressor Blankets – Acoustic compressor sound
blankets are optional to reduce compressor noise.
Acoustic Perimeter Enclosures (field mounted)
– Perimeter enclosure option provides acoustically
tuned panels around the bottom of the chiller to reduce
noise.
VIBRATION ISOLATION
Neoprene Pad Isolation – Recommended for normal
installations (Field-mounted).
1” (25 mm) Spring Isolators – Level adjustable,
spring and cage type isolators for mounting under the
unit base rails (Field-mounted).
2” (51 mm) Seismic Spring Isolators – Restrained
Spring-Flex Mountings incorporate welded steel hous-
ing with vertical and horizontal limit stops. Housings
designed to withstand a minimum 1.0 g accelerated
force in all directions to 2” (51 mm). Level adjustable,
deection may vary slightly by application (Field-
mounted).