Trane ctv-prc007-en User Manual
CenTraVac
™
Liquid Chillers
Centrifugal Liquid Chillers/
Water-Cooled
170-3500 Tons
50 and 60 Hz
Built For the Industrial and Commercial Markets
CVHE — Three Stage
170
CVHF — Two-Stage CenTraVac
325 1750
LHCV — Module CenTraVac
1300
GPC — Gas Powered CenTraVac Package
170
500
CVHG — Three Stage
450 1300
3500
3500
CTV-PRC007-ENApril 2001
World’s Most
Efficient Lowest
What We Mean By Earth•Wise
Breaking the .48 kW/Ton
Efficiency Barrier
The Trane Earth•Wise CenTraVac has a
proven track record as literally the
world’s most efficient, lowest emissions
chiller. In fact, a portion of the product
line is selectable at an unmatched
efficiency level of .48 kW/ton, at standard
ARI rated conditions. This is an efficiency
level of 16 to 25 percent better than
competitive chillers using other
alternative refrigerants, which are
typically in the .56 to .60 kW/ton range.
On a 1000-ton chiller, this efficiency
difference can provide savings of over
$24,000 per year or nearly three quarters
of a million dollars over the life of the
machine . . . typically more than twice
the initial cost of the machine. And, at
part-load conditions, the kW/ton ratings
are even better; a fact that can be seen
by comparing Trane’s ARI certified
applied part load values (NPLV’s) to
those of competitive units.
The development of the .48 kW/ton
chiller also has a positive environmental
impact. Consider this:
If every centrifugal chiller in the world
were able to operate at .48 vs .56 kW/ton,
utility generated greenhouse gas
emissions could be reduced annually by
nearly 17 billion pounds of CO
SO
and NO
2
64 and 27 billion grams, respectively.
This reduction is equivalent to removing
more than two million cars from the
road or to planting nearly 500 million
trees each year.
could be reduced by over
x
while
2
Introduction
Lowest Total Refrigerant
Emissions In The Industry
Furthermore, the Trane “near zero”
emissions Earth
the lowest total refrigerant emissions in
the industry. So low that it’s essentially
a closed system.
The key to the industry’s highest energy
efficiency and lowest leak rate is the
use of a low pressure refrigerant
DuPont calls SUVA-123; a refrigerant
that has the lowest direct-effect global
warming potential and the highest
thermodynamic efficiency of all nonCFC refrigerants; a refrigerant in use in
more new centrifugals today than all
other alternatives combined.
Balancing Our Accountability
for Ozone Depletion, Global
Warming and Energy
Efficiency
Reduced power plant emissions and
the industry’s lowest refrigerant
emission rate put the Trane .48 kW/ton
Wise centrifugal chiller in a class
Earth
•
by itself, from both a business and an
environmental standpoint. The future
lies in the prudent balance that takes
into account the importance of ozone
depletion, global warming and energy
efficiency. A balance that is right for
both business and the environment.
Wise chiller also has
•
Emissions Chiller
Built For The Industrial Market
Direct drive for reliability
•
Multi-stage compressor for efficiency.
•
“Near Zero” refrigerant emission
•
design.
Evaporator and condenser designed to
•
maximize efficiency and reduce
operating costs.
Proven shell and tube design offering a
•
variety of high performance heat
transfer surfaces.
Evaporator, condenser and
•
compressor combinations allow
selection of a chiller that best meets
the system requirements.
Options like heat recovery, free
•
cooling, auxiliary condensers, ice
storage and a unit-mounted starter for
expanded capability and maximum
efficiency.
Complete factory assembly of the
•
CenTraVac
assembly labor and expense.
Machines designed for operating with
•
environmentally acceptable HCFC-123.
Trane patented fixed orifice system for
•
ensuring proper refrigerant flow at all
load conditions. This eliminates the
need for other moving parts such as
float valves, expansion valves.
Low speed direct drive capability offers
•
up to 5 percent more energy efficiency,
at full load, than gear drive chillers.
Also, low speed direct-drive operation
improves reliability and maintenance
costs are also lower.
CenTraVac control panel
•
Adaptive Control
•
Microprocessor based
•
Complete operating status and
•
diagnostics display.
Interfaces with building management
•
system.
High efficiency Purifier™ Purge works
•
as an early warning leak detector that
also takes purge refrigerant emissions
to an industry low.
™
options for reduced jobsite
™
CTV-PRC007-EN©American Standard Inc. 2001
Contents
Introduction
Features and Benefits
Components, Standard and Optional Features,
Factory Performance Testing,
Refrigeration Cycle, Control Panel
Unit Options
Unit Mounted Starter, Adaptive Frequency Drives,
Free Cooling
System Options
Auxiliary Condenser, Ice Storage, Heat Recovery,
Chilled Water Resets
Application Considerations
Selection Procedure
Performance Data
Jobsite Connections
2
6
13
21
26
28
30
32
CTV-PRC007-EN
Controls
Weights
Physical Dimensions
Mechanical Specifications
33
39
41
48
3
Trane Hermetic
Centrifugal
A Tradition of Innovation
The first Trane centrifugal chiller, the
Turbovac™ was introduced in 1938. The
simple, direct drive, slow speed design
of the Turbovac revolutionized the air
conditioning industry. The chiller was
attractive to customers because its
hermetic design reduced frequent
service requirements.
™
In 1951 the Trane CenTraVac
chiller was introduced. Its unique two
stage compressor with multiple inlet
guide vanes and patented economizer
reduced energy consumption on typical
applications to less than 0.8 kW/ton.
The model PCV CenTraVac chiller that
was introduced in 1966, allowed quality
air conditioning for applications as small
as 120 tons.
In 1982 the CenTraVac chiller solidified
its position as the industry leader by
introducing a three-stage compressor
and a two-stage economizer. As a result,
this chiller was 5 to 20 percent more
efficient than previous designs.
Today’s CenTraVac chiller still relies on
the dependability of the proven direct
drive and exclusive slow speed
operation. Low operating costs and high
reliability continue to be the CenTraVac
chiller hallmark.
When a source of energy other than
electricity is required
The Trane CenTraVac has the standard
option of being coupled to a Waukesha
Enginator to quite simply convert
natural gas to chilled water. With COPs
in the range of 1.5 to 2.2 depending on
options selected, makes this option a
very simple and attractive alternative
when an alternative fuel source is
desired.
centrifugal
Introduction
Trane GPC* Benefits
Combines two industry-recognized
•
and proven products, the Trane
Earth•Wise CenTraVac and Waukesha
Enginator
Ability to do both base and peak
•
shaving
No on-site piping connections
•
Refrigerant leaks minimized
•
No need to remove refrigerant
•
charge from chiller during downtime
Installations more flexible, simpler
•
and cost effective
Ability to place the engine generator
•
set in a location remote of the chiller
Allows for efficient use of plant floor
•
space
Provides flexibility in sound sensitive
•
work areas
*Limited availability for International orders –
Please contact International CenTraVac Marketing
Group.
Unmatched Expertise
The performance and reliability of a
CenTraVac
of experienced field sales engineers with
support from headquarters experts. No
other manufacturer can offer that degree
of support to its customers.
In the design phase, application
engineers can help answer your
questions or solve your problems.
During the selection phase, software
engineers are available to help you
evaluate equipment alternatives. At the
installation stage, field start-up of the
CenTraVac chiller is included in the
purchase price. Trane offers this support
and more when you need it.
Delivery And Design Flexibility
If delivery time is a priority, Trane can
meet your needs with a variety of quick
shipment choices. Most fast track
building schedules can be met with one
of these choices.
Design flexibility means Trane can
custom build a unit to specific job
requirements. Design parameters such
as shell type, compressor, kW/ton,
waterside pressure drop, as well as full
and part load performance can be built
to meet requirements.
™
chiller is backed by a team
Water Chillers
ISO 9001 Certification
ISO 9001 Certification applies to the
Trane La Crosse Business Unit. This
process is based on the La Crosse
Business Unit’s ISO 9001 certified quality
system. This system is documented in
procedures which define how quality
assurance activities are managed,
performed, and continuously monitored.
Included in the system are verification
checkpoints from the time the order is
entered until final shipment. In addition,
product development for the
marketplace is subjected to formal
planning, review and validation. The
system is designed to assure maximum
consistency in meeting customer
requirements.
The Beauty of Simplicity
The reliability of a centrifugal chiller
starts with its basic product design. At
Trane we’ve found that the straightest
path to reliability is simplicity. Years of
research and field testing have honed
the design of the CenTraVac chiller to a
simple, precise solution to a complex
engineering problem.
This simple design provides efficiency
and reliability benefits. The Trane
CenTraVac chiller has only one moving
part — no gear boxes, couplings or extra
shafts. The single rotating shaft is
supported by two aircraft turbine grade/
rated bearings. This direct drive concept
minimizes the chance of failure for
moving parts. It also reduces wear and
drag on parts, resulting in more efficient
operation.
CTV-PRC007-EN4
Introduction
1939 — The Trane Turbovac
1951 — The original Trane CenTraVac
chiller
1965 — The Model PCV CenTraVac
chiller
Specific Trane centrifugal chiller
performance is certified by ARI Standard
550/590. Trane centrifugal chillers tested
within the scope of the ARI program
display the ARI symbol of compliance
(shown on back cover) to certification
sections of ARI Standard 550/590.
™
Purifier
rated in accordance with ARI
Standard 580.
Those applications in this catalog
specifically excluded from the ARI
certification program are:
•
•
•
•
•
•
•
purge with Purifier Plus™ are
Low temperature applications,
including ice storage
Glycol
Chillers above 2000 tons
Free cooling
Heat recovery
Auxiliary condenser
Chillers that are 50 Hertz
1992 — The two-stage CVHF CenTraVac
1982 — The three-stage CVHE CenTraVac
Chiller
1992 — The LHCV CenTraVac Modular Chiller system
//
115 VAC/60 Hz/50 Hz
//
1997 — The Gas Powered CenTraVac (GPC) Chiller Package
Chiller
3 Phase Power
Control Interface
Control Interface
CTV-PRC007-EN
5
Attributes of
Features and Benefits
Comparing the Attributes of
Low Pressure Chiller Operation
to High Pressure Chiller
Operation.
Trane CenTraVac chillers continue to offer
time tested and proven low pressure
refrigerants including the alternative
Evaporator
Condenser
Monitoring
of leak rate in-leakage with a purge timer — periodic leak checks
Typical
Pressures Evap: 18.7 inches of Mercury Evap: 33.1 psig
(38°F evap.) Cond: 6.1 psig Cond: 124.1 psig
(100°F cond.)
*Trane Purifier Purge efficiency does not exceed 0.002 lbs./refrigerant/lbs.-air
Low Pressure Medium/High Pressure
Always at low negative pressure
•
Air leaks inward at low rate
•
Refrigerant lost: (# air leak in) x purge efficiency*
•
No refrigerant loss is into equipment room (vented to the
•
outside via purge)
At positive pressure during operation
•
Usually at negative pressure during inactivity (air leaks
•
inward)
Refrigerant leaks outward at very low rate during operation
•
Trane Purifier Purge is able to continuously monitor
•
Refrigerant monitor as required by ASHRAE — purchase refrigerant monitor
•
Purge timer can be connected to building automation
•
system for notification of increased purge operation (inleak). Similarly, the refrigerant monitor can be connected to pressure chiller is during spring start-up. This means that a
the building automation system. chiller which develops a leak in the summer, may leak
HCFC-123 HFC-134a
environment friendly HCFC- 123. Trane
CenTraVac chillers provide the safety of
low pressure with continued product
improvement in leak proof design.
Consider the following benefits of low
pressure over high pressure chillers.
Always at positive pressure
•
Refrigerant leaks outward at moderate rate
•
Refrigerant loss is into equipment room
•
Always at high positive pressure
•
Refrigerant leaks outward at very high rate
•
Only ways to monitor leak rate on high pressure chiller are
•
Refrigerant monitor as required by ASHRAE
•
Normally the only time that a leak is detected on a high
•
continuously until the following spring.
Low Pressure
Chiller Operation
CTV-PRC007-EN6
Features and
Control
Benefits
Operator Control Panel
Trane has multi-language support for all
chillers controlled by the UCP2
including but limited to: CVHE, CVHF,
CVHG, GPC and LHCV alarm. The
standard Clear Language Display (CLD)
supports eight languages including
English, French, German, Spanish,
Katakana, Italian, Portuguese and Dutch.
The Complex Character CLD was added
to support languages such as Traditional
and Simplified Chinese, Japanese, Thai
and Korean.
The Complex Character CLD is available
as a retrofit kit for the standard CLD on
the UCP2 panel. With the same wiring
and mounting, it is as simple as
disconnecting two wires, unbolting the
existing CLD, bolting on the Complex
Character CLD and reconnecting the two
wires.
™
Panel
Capabilities include:
Super-twist LCD display with
•
backlighting for readability.
Chiller data (more than 200 items)
•
including:
- Status
- Setpoints
- Field start-up items
- Machine configuration items
- Service test items
Status reports:
•
- Chiller Report
- Refrigerant Report
- Compressor Report
Custom report capability.
•
More than 100 diagnostic messages
•
including a history log of the last 20
diagnostics
- An alarm indicator
- Expanded help messages
- Operator security
- Internationally recognized symbols
CTV-PRC007-EN
7
Features and
Internally enhanced or
smooth bore tubes
Benefits
Various tube materials
and thicknesses
Components
Controls and paints for outdoor
use or corrosive environments
Victaulic or
flanged
connections
Marine or standard
waterboxes
1, 2, 3, pass evaporator
Factory installed insulation
Special construction to facilitate
chiller disassembly for construction
projects with tight space clearances
or component weight limitations
UL label
Full complement of electrical
starters and accessories
(unit mounted or remotely)
- Panel chilled water reset
- External chilled water and current limit
setpoints
- Evaporator / Condenser differential
pressure
- Condenser relief request
- Maximum capacity
- Communication link to BAS
- Printer module
CTV-PRC007-EN8
Standard
Features and
Benefits
Standard Features
The following features are provided as
standard with all Trane CenTraVac
chillers:
Motor-compressor assembly with
•
integral lubrication system.
Evaporator condenser assembly.
•
Two-stage economizer assembly on
•
CVHE/CVHG style units (single-stage on
CVHF style units).
Prewired instrument and control panel.
•
Oil and refrigerant charge.
•
Oil heater.
•
Isolation pads
•
Wiring and conduit for purge and oil
•
system interconnection to the main
control panel.
Installation, operation, and
•
maintenance instructions.
Start-up and operator instruction
•
service.
Advanced motor protection.
•
CenTraVac Motor
The motor provided in the Trane
CenTraVac chiller is a specially designed
squirrel cage, two pole induction motor
suitable for 50 and 60 hertz, three-phase
current.
Trane CenTraVac motors are cooled by
liquid refrigerant surrounding the motor
windings and rotor. Use of liquid
refrigerant results in uniform low
temperatures throughout the motor,
thereby promoting long motor life.
Refrigerant/Oil Pump Motor
The oil pump motor is a 120 volt,
50/60 hertz,
protective fusing and panel mounted
contactor.
Purge
The purge unit motor is a 120 volt,
50/60 hertz,
integral overload protection and panel
mounted contactor.
The use of an air-cooled condensing unit
obtains separation temperatures in the
purge drum as low as 0°F. Normal
operating efficiency does not exceed
0.002 lbs. of refrigerant lost per pound of
dry air removed. The purge system can
be operated at any time, independent of
chiller operation.
3
/4 hp, 1 phase motor with
3
/4 hp, 1 phase motor with
™
and Optional
Features
Optional Features
Trane offers a selection of optional
features to either complete the basic
chiller installation or to allow
modification for special purpose
applications.
Medium voltage (over 600 volts)
•
hermetic compressor motor
construction.
Complete line of compressor motor
•
starters.
Unit mounted starter accessory on low
•
voltage units up to an RLA of
1080 amps.
Marine waterboxes for evaporators
•
and condensers
High pressure (300 psig working
•
pressure) water side construction.
Free cooling.
•
Heat recovery or auxiliary condensers.
•
Smooth bore tubing.
•
Factory-applied thermal insulation
•
One-inch deflection spring isolators for
•
vibration-sensitive installations.
Building automation systems (BAS)
•
interface
Variable speed drives
•
Internally enhanced tubes
•
Various tube wall thicknesses
•
UL Label
•
Three pass evaporator/one pass
•
evaporator
Special construction to facilitate chiller
•
disassembly at the job
CuNi Tubes
•
Special paint and controls for outdoor
•
use or corrosive environments
Unit mounted refrigerator monitor
•
CTV-PRC007-EN
9
Factory
Factory Testing for
Assured Performance
To prove that your chiller will perform as
promised, Trane offers factory
performance testing, which you can
witness.
Trane provides laboratory-grade,
calibrated performance testing on
ARI approved test loops that proves the
performance of the chiller tailored to
your application. The test provides:
Confirmed efficiency
•
Confirmed capacity
•
Smooth trouble-free start-up confirmed
•
through factory testing and
commissioning of both chiller and
controls
Trane believes centrifugal chiller testing
is so important that we invested over $2
million in CenTraVac testing facilities.
Testing is in accordance with ARI
Standard 550/590 and calibration of
instrumentation meets or exceeds the
National Institute of Standards
Technology (NIST).
The industry has responded to the
demand for more efficient chillers by
developing machines with component
mix-matching and many money saving
options. It’s possible that with the
thousands of component combinations
available, a specific chiller combination
may be laboratory tested for the first
time.
Trane offers two levels of CenTraVac
performance testing:
A performance test at design
•
conditions plus a certified test report.
A customer-witnessed performance
•
test at design conditions plus a certified
test report.
Trane is part of the ARI 550/590
certification program. The selection
program and machines bear the ARI seal
of approval. Performance testing is a key
part of this program. While the
certification program is technically
sound, a factory run test, with your
machine on the test stand, is still the best
way to confirm machine performance
and a trouble-free start-up.
Features and
Benefits
The single package design of the
CenTraVac chiller allows testing of each
assembled chiller at the factory. Actually
all components including the evaporator,
condenser, compressor and control
During customer witnessed performance tests of Trane CenTraVac chillers, a nickel
can be balanced on the edge of the compressor-motor assembly, demonstrating the
extremely low vibrations generated by the unit while operating at full and part load
conditions.
Performance
Testing
panel are tested before final assembly.
After assembly, performance testing of
the chiller can confirm proper operation
and virtually eliminate jobsite start-up
problems.
CTV-PRC007-EN10
Features and
Refrigeration
Design Simplicity
Impellers are keyed directly to the motor
shaft for high reliability and performance
and low life-cycle costs.
Reliable Motor Cooling
The motor is engulfed in liquid
refrigerant to provide efficient, complete
cooling at all load conditions. This
system is reliable and easy to maintain.
Fixed Orifice Flow Control
For proper refrigerant flow control at all
load conditions, the CenTraVac design
incorporates the Trane patented fixed
orifice system. It eliminates float valves,
thermal expansion valves and other
moving parts. Since there are no moving
parts, reliability is increased.
Quiet Operation
With only one moving component — the
rotor and impeller assembly — the Trane
low speed, direct drive design operates
exceptionally quietly. The smoothly
rotating CenTraVac compressor is
inherently quieter than other compressor
types. Typical CenTraVac chiller sound
measurements are among the quietest in
the industry. Trane can guarantee sound
levels with factory testing and
measurements in accordance with
ARI standard 575.
The Reliability Standard
Just as a multi-stage turbine is more
efficient than a single stage turbine, the
CenTraVac multi-stage compressors are
more efficient and reliable than singlestage designs.
Benefits
Cycle
The CenTraVac™ Chiller Operating Cycle
Direct Drive Design — No Gear Losses
The direct drive compressor operates
without speed increasing gears, thus
eliminating gear energy losses.
Compressors using gears suffer mesh
losses and extra bearing losses in the
range of three to five percent at full load.
Since these losses are fairly constant
over the load range, increasingly larger
percentage losses result as load
decreases.
Multiple Stages of Compression
The compressor operates more
efficiently over a wide range of
capacities, virtually eliminating the need
for energy wasting hot gas bypass as
typically found on single stage chillers.
The radial component of velocity
determines the ability of the chiller to
resist interruption of smooth refrigerant
flow when operating at light loads and
with high condensing temperatures. This
interruption in flow and unstable
operation, called “surge” is avoided with
the two-stage design.
Inlet Guide Vanes
Part load performance is further
improved through use of moveable
designed variable inlet guide vanes. Inlet
guide vanes improve performance by
throttling refrigerant gas flow to exactly
meet part load requirements and by
prerotating refrigerant gas for optimum
entry into the impeller. Prerotation of
refrigerant gas minimizes turbulence and
increases efficiency.
Two-Stage Economizer
The CVHE/CVHG CenTraVac chiller has a
two-stage economizer — providing up to
seven percent greater efficiency than
designs with no economizer. Since the
CVHE/CVHG uses three impellers, it is
possible to flash refrigerant gas at two
intermediate pressures between the
evaporator and condenser pressures,
significantly increasing chiller efficiency.
This improvement in efficiency is not
possible in single-stage chillers since all
compression is done by one impeller.
Single Stage Economizer
The CVHF CenTraVac chiller has a singlestage economizer — providing up to 4
percent greater efficiency than designs
with no economizer.
Since the CVHF CenTraVac uses two
impellers, it is possible to flash
refrigerant gas at an intermediate
pressure between the evaporator and
condenser pressures, significantly
increasing chiller efficiency. This
improvement in efficiency is not possible
in single-stage chillers since all
compression is done by one impeller.
1
/2
CTV-PRC007-EN
11
Features and
Refrigeration
Three-Stage CenTraVac P-H Diagram
CenTraVac™ Three-Stage P-H Diagram
The pressure-enthalphy (P-H) diagram
describes refrigerant flow through the
major CVHE/CVHG chiller components.
This diagram confirms the superior
operating cycle efficiency of the threestage compressor and two-stage
economizer.
Evaporator — A liquid-gas refrigerant
mixture enters the evaporator at state
point 1. Liquid refrigerant is vaporized to
state point 2 as it absorbs heat from the
system cooling load. The vaporized
refrigerant then flows into the
compressor first stage.
Compressor First Stage — Refrigerant
gas is drawn from the evaporator into
the first stage compressor. The first stage
impeller accelerates the gas increasing
its temperature and pressure to state
point 3.
Compressor Second Stage —
Refrigerant gas leaving the first stage
compressor is mixed with cooler
refrigerant gas from the low pressure
side of the two-stage economizer. This
mixing lowers the enthalpy of the
mixture entering the second stage. The
second stage impeller accelerates the
gas, further increasing its temperature
and pressure to state point 4.
Compressor Third Stage — Refrigerant
gas leaving the compressor second
stage is mixed with cooler refrigerant
gas from the high pressure side of the
two-stage economizer. This mixing
lowers the enthalpy of the gas mixture
entering the third stage compressor. The
third stage impeller accelerates the gas,
Benefits
further increasing its temperature and
pressure to state point 5, then discharges
it to the condenser.
Condenser — Refrigerant gas enters the
condenser where the system cooling
load and heat of compression are
rejected to the condenser water circuit.
This heat rejection cools and condenses
the refrigerant gas to a liquid at state
point 6.
Patented Two-Stage Economizer and
Refrigerant Orifice System-Liquid
refrigerant leaving the condenser at state
point 6 flows through the first orifice and
enters the high pressure side of the
economizer. The purpose of this orifice
and economizer is to preflash a small
amount of refrigerant at an intermediate
pressure called P1. P1 is between the
evaporator and condenser pressures.
Preflashing some liquid refrigerant cools
the remaining liquid to state point 7.
Refrigerant leaving the first stage
economizer flows through the second
orifice and enters the second stage
economizer. Some refrigerant is
preflashed at intermediate pressure P2.
Preflashing the liquid refrigerant cools
the remaining liquid to state point 8.
Another benefit of preflashing refrigerant
is to increase the total evaporator
refrigeration effect from RE’ to RE. The
two-stage economizer provides a seven
percent energy savings compared to
chillers with no economizer.
To complete the operating cycle, liquid
refrigerant leaving the economizer at
state point 8 flows through a third orifice
system. Here, refrigerant pressure and
temperature are reduced to evaporator
conditions at state point 1.
Two-Stage CenTraVac P-H Diagram
Cycle (Cont.)
CenTraVac Two-Stage P-H Diagram
The pressure-enthalphy (P-H) diagram
describes refrigerant flow through the
major CVHF chiller components. This
diagram confirms the superior operating
cycle efficiency of the two- stage
compressor and economizer.
Evaporator — A liquid-gas refrigerant
mixture enters the evaporator at state
point 1. Liquid refrigerant is vaporized to
state point 2 as it absorbs heat from the
system cooling load. The vaporized
refrigerant then flows into the
compressor first stage.
Compressor First Stage — Refrigerant
gas is drawn from the evaporator into
the first stage compressor. The first stage
impeller accelerates the gas increasing
its temperature and pressure to state
point 3.
Compressor Second Stage —
Refrigerant gas leaving the first stage
compressor is mixed with cooler
refrigerant gas from the economizer.
This mixing lowers the enthalpy of the
mixture entering the second stage. The
second stage impeller accelerates the
gas, further increasing its temperature
and pressure to state point 4.
Condenser — Refrigerant gas enters the
condenser where the system cooling
load and heat of compression are
rejected to the condenser water circuit.
This heat rejection cools and condenses
the refrigerant gas to a liquid at state
point 6.
Economizer and Refrigerant Orifice
System-Liquid refrigerant leaving the
condenser at state point 6 flows through
the first orifice and enters the
economizer. The purpose of this orifice
and economizer is to preflash a small
amount of refrigerant at an intermediate
pressure called P1. P1 is between the
evaporator and condenser pressures.
Preflashing some liquid refrigerant cools
the remaining liquid to state point 8.
Another benefit of flashing refrigerant is
to increase the total evaporator
refrigeration effect from RE’ to RE. The
economizer provides a 4
energy savings compared to chillers with
no economizer. To complete the
operating cycle, liquid refrigerant leaving
the economizer at state point 8 flows
through a second orifice system. Here,
refrigerant pressure and temperature are
reduced to evaporator conditions at state
point 1.
1
/2 percent
CTV-PRC007-EN12
Unit
Unit Mounted
Unit-Mounted Starters
Trane factory installed options make
installation of a CenTraVac™ chiller easier,
faster and less costly. Another example
of the Trane packaged concept is the
factory installed unit-mounted star delta
starter available on CenTraVac chillers up
to 1300 tons capacity or solid-state
starters up to 1000 tons, depending on
jobsite electrical requirements. It’s a
single chiller/starter package designed
for years of reliable operation and low
life-cycle costs.
Installation cost is reduced by eliminating
chiller-to-starter, starter-to-disconnect
and starter-to-control panel field wiring.
All this wiring is completed and tested in
the factory, ensuring electrical integrity.
Since most wiring is factory completed,
electrical system design time is reduced.
Starter components are pre-engineered
and selected to provide a reliable, cost
effective chiller/starter package. This
single source responsibility for the
CenTraVac chiller and unit-mounted
starter package is a real advantage.
Potential scheduling problems
associated with separate starter and
chiller installations are eliminated. When
the CenTraVac chiller arrives at the
jobsite with the unit-mounted starter, the
only remaining wiring is the main power
wiring to the disconnect switch, and a
few simple electrical interlocks to the
chilled water and condenser water flow
sensing devices.
To ensure a trouble-free start-up on the
electrical side, the unit-mounted starter is
tested with the chiller as part of the
factory performance testing program.
Our commitment to customer and
equipment safety offers the Underwriters
Laboratories Inc. (UL) mark of safety on
both chiller and starter and available
accessories.
Compressor Motor Starting Equipment
Features
Trane can provide compressor motor
starting equipment built to rigid Trane
specifications. The types of starters
available include:
Low Voltage (200 to 600 volts)
Star (wye)-delta closed transition
•
Full voltage
•
Options
Autotransformer, closed transition
•
Solid-state starters
•
Medium Voltage (2300 to 6000 Volts)
Full voltage
•
Primary reactor, closed transition
•
Autotransformer, closed transition
•
Medium voltage starters are provided as
standard with a non-load break isolation
switch and current limiting fuses.
All starters provided by Trane include the
following standard features for safe,
efficient application and ease of
installation:
NEMA 1 starter enclosure.
•
120 volt, 60 hertz, 1 phase fused pilot
•
and safety circuits.
Control power transformer (4.0 KVA)
•
with 120 volt, 50 or 60 hertz, singlephase.
One pilot relay to initiate start
•
sequence from CenTraVac control
circuit signal.
Starter enclosures capable of being
•
padlocked.
Automatic transfer from wye to delta
•
on any two-step starter.
In addition, Trane offers a wide selection
of optional starter features.
Starters with standard or high
•
interrupting capacity circuit breakers,
to provide disconnect means and short
circuit protection (low voltage only).
Ammeters and voltmeters.
•
Special function pilot lights.
•
Special NEMA enclosures.
•
Ground fault protection.
•
Power factor correction capacitors.
•
I.Q. Data Plus monitor device.
•
If the CenTraVac compressor starting
equipment is provided by others, the
starter must be designed in accordance
with the current Trane standard
engineering specification “Water-Cooled
CenTraVac
also recommended that two copies of
the interconnecting and control circuit
wiring diagrams be forwarded to The
Trane Company for review. This service
is provided at no charge, and is intended
to help minimize the possibility that
Trane CenTraVac chillers will be applied
in improper starting and control
™
Starter Specification.” It is
Starter
systems. However, the responsibility for
providing proper starting and control
systems must remain with the system
designer and the installer.
Contact your local Trane sales office for
further information.
The typical equipment room layout for a
Trane CenTraVac
mounted starter are shown in Figures
O-1 and O-2. A NEMA 1, star-delta (wyedelta) type closed transition reduced
voltage motor starter is mounted, as an
optional accessory, on Trane CenTraVac
chillers rated up to and including 1080
RLA on low voltage (600 volts and
below) systems. All power and control
wiring between the starter and the chiller
are factory assembled. Factory assembly
enhances total system reliability and
integrity. Total installed chiller/starter
costs are significantly reduced by the
unit mounted starter option rather than a
conventional remote mounted starter.
Benefits
Reduces starter installation costs 20 to
•
35 percent:
By eliminating chiller-to-starter field
•
wiring
By eliminating starter-to-disconnect
•
switch field wiring (when optional
circuit breaker is used)
By eliminating field installed
•
disconnect switch (when optional
circuit breaker is used)
By eliminating starter mounting pad
•
and required equipment room floor
space
By eliminating control wiring from
•
starter to control panel
Electrical system reliability is
•
enhanced:
By reducing the number of field
•
electrical connections
By making starter-to-chiller electrical
•
connections under factory-controlled
conditions
By testing the entire chiller/starter
•
combination, in the factory
By providing control components
•
designed to operate with the unique
CenTraVac motor/compressor start and
protection subsystem
Single Source Responsibility
•
Trane retains complete responsibility
for the starter and associated chiller/
starter interconnecting wiring.
™
unit or remote
CTV-PRC007-EN
13
Unit
Unit Mounted
Options
System Design Time Cost Savings
•
System design time is reduced, since
all starter components and
interconnecting wiring are preengineered and selected.
Complete package available with
•
Agency Approval
Application
•
The Trane unit mounted starter can be
applied on low voltage (600 volts) and
below applications up to
approximately 1300 tons capacity. To
determine the unit mounted starter to
be used with a particular selection, it is
necessary to know the current draw of
the compressor motor. The starter
current draw must be greater than, or
equal to, the compressor motor
current draw.
Figure O-1 – Typical Equipment Room Layout – Conventional Remote Star-Delta Starter
Figure O-2 – Typical Equipment Room Layout – Unit-Mounted Star-Delta Starter
Reliability
•
The unit mounted starter is a star-delta
closed transition electromechanical
starter. Motor starters of this
configuration have proven reliability in
thousands of centrifugal chiller
applications around the world. The
proven electromechanical concept plus
the use of industrial quality
components makes the CenTraVac unit
mounted starter dependable in all kinds
of service applications.
Operation
The unit mounted starter is a star (wye)
delta, closed transition, reduced voltage
starter. When starting and during
acceleration, the motor is connected in
its wye configuration. Because of this
arrangement the voltage applied to the
Starter (Cont.)
motor windings is reduced to one
divided by the square root of three or
0.58 times line voltage. This reduction in
winding voltage results in a reduction in
inrush current. The inrush current is 0.33
times the full voltage locked rotor current
rating of the motor. The accelerating
torque of the motor is also reduced to
0.33 times the full voltage torque rating.
This is sufficient to fully accelerate the
compressor motor. The unit control
panel monitors motor current during
operation via current transformers
located in the starter enclosure. When
during acceleration the line current
drops to approximately 0.85 times rated
load current, transition is initiated. The
closed transition feature provides for a
continuous motor current flow during
transition by placing resistors in the
circuit momentarily. This prevents
buildup of damaging torques to the
system during this period. With the
completion of transition, the motor
windings are connected in the delta
configuration with full line voltage.
Three precision current transformers
monitor phase current. Contactor
position and various voltage signals
provide extensive interlocking between
the starter and the microcomputer in the
CenTraVac
subsequent instruction originate in the
unit control panel. Protection against the
following starter defects is provided:
High motor current (starting and
•
running)
Improper starter circuitry
•
Excessive accelerating time
•
Incomplete starting sequence
•
Loss of phase
•
Phase amperage unbalance
•
Phase reversal
•
Distribution fault
•
Features
The Trane CenTraVac Unit Mounted
Starter includes the following standard
features:
NEMA 1 enclosure, designed to
•
accommodate padlock
3 KVA control power transformer with
•
120V secondary
Fused 120V control circuit
•
3-phase incoming line terminals
•
6 output load terminals factory-
•
connected to the motor
™
control panel. All logic and
CTV-PRC007-EN14
Unit
Unit Mounted
Available options include:
Circuit Breaker — A standard
•
interrupting capacity circuit breaker is
available. The circuit breaker is
mechanically interlocked to disconnect
line power from the starter when the
starter door is open.
High Interrupting Capacity Circuit
•
Breaker — A high interrupting capacity
circuit breaker is available. This breaker
is also interlocked to disconnect line
power from the starter when the
starter door is open.
Circuit Breaker with Ground Fault —
•
Ground Fault protection is available
with either standard or high
interrupting capacity circuit breakers.
An indicating light is provided to
indicate if a ground fault has occurred.
Current Limiting Circuit Breaker — A
•
standard circuit breaker incorporating
the current limiters with fuse links is
available. A fault current in excess of
the circuit breaker capacity will blow
the fuse links and interrupt the fault
current. The circuit breaker cannot be
reset until the blown current limiters
are replaced.
Ground fault detection and protection
•
(available only with circuit breaker
options)
Options
The solid-state starter controls the
starting characteristics of a motor by
controlling the current that flow to the
motor. It does so through the use of
SCRs (Silicon Controlled Rectifiers),
which are solid-state switching devices,
and an integral bypass contactor for
power control.
SCR’s
An SCR will conduct current in one
direction only when a control signal
(gate signal) is applied. Because the
solid-state starter is for use on AC
(alternating current), two SCR’s per
phase are connected in parallel,
opposing each other so that current may
flow in both directions. For three- phase
loads, a full six-SCR configuration is
used. The connection is shown in Figure
O-3.
During starting, control of current or
acceleration time is achieved by gating
the SCR on at different times within the
half-cycle. The gate pulses are originally
applied late in the half-cycle and then
gradually applied sooner in the halfcycle. If the gate pulse is applied late in
the cycle, only a small increment of the
wave form is passed through, and the
output is low.
Starter (Cont.)
If the gate pulse is applied sooner in the
cycle, a greater increment of the wave
form is passed through, and the output
is increased. So, by controlling the SCR’s
output voltage, the motor’s acceleration
characteristic and current inrush can be
controlled. These forms are shown in
Figure O-4.
Integral Bypass Contactors
When the SCR’s are fully “phased on,”
the integral bypass contactors are
energized. The current flow is transferred
from the power pole to the contactors.
This reduces the energy loss associated
with the power pole, which is otherwise
about one watt per amp per phase.
When the starter is given the stop
command, the bypass contactors are deenergized, which transfers the current
flow from the contactors back to the
power poles. Two-hundred fifty
milliseconds later, the SCR’s are turned
off, and the current flow is stopped.
CTV-PRC007-EN
Figure O-3 — Six-SCR Configuration
Figure O-4 — Wave Forms
15
Unit
Adaptive
Benefits
Trane Adaptive Frequency drives*
provide motor control, but they are
much more than just starters. They also
control the operating speed of the chiller
compressor motor by regulating output
voltage in proportion to output
frequency. Varying the speed of the
compressor motor can translate into
significant energy cost savings.
Reliable, Optimized Compressor
Efficiency for Energy Savings
Conventional chillers use inlet vanes to
provide stable operation at part-load
conditions. Capacity is reduced by
closing the vanes while maintaining a
constant motor speed. The drive can be
used to significantly reduce power
consumption by reducing motor speed
at low load conditions. Trane patented
AFD Adaptive Control
allows inlet guide vane and speed
control combinations that optimize partload performance.
To Avoid Mechanical Stress
Controlled “soft” start with linear
acceleration results in limited starting
current to eliminate motor stress, reduce
power line disturbance and provide a
lower power demand on start. Reduced
motor speed as a result of reduced
chiller load means less current drawn,
less heat generated, increased motor
winding life. This translates into longer
time between compressor maintenance
and less downtime throughout the life of
the machine.
Application
Certain system characteristics favor
installation of an AFD because of energy
cost savings and shorter payback.
Among them are:
A large number of part-load operating
hours annually
Figure O-4, based on a CVHE500, 500-ton
load at standard ARI conditions, shows
that major kW savings occur at part-load
conditions, typically below 90 percent
load.
™
logic safely
Options
Figure O-4 — CVHE500 Part Load Efficiencies with/without AFD
Frequency Drives
CTV-PRC007-EN16
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