Operating Principles Mechanical - Trane CITY RTSF Series Manual

Operating Principles Mechanical

This section contains an overview of the operation and maintenance of RTSF chillers equipped with microcomputer-
based control systems. It describes the overall operating principles of the design. Following the section is
information regarding specifi c operating instructions, detailed descriptions of the unit controls and options and
maintenance procedures that must be performed regularly to keep the unit in top condition. Diagnostic information
is provided to allow the operator to identify system malfunctions.
Note: To ensure proper diagnosis and repair, contact a qualifi ed service organization if a problem should occur.
General
The unit is mono compressor, single circuit, water- cooled liquid chillers. These units are equipped with unit mounted
starter/control panels. The basic components of RTSF unit are:
• Unit-mounted panel containing starter and Tracer UC800 controller and Input/output LLIDS
• Helical-rotary compressor
• Evaporator
• Electronic expansion valve
• Water-cooled condenser
• Oil supply system
• Oil cooler (application dependent)
• Related interconnecting piping
• AFD (Adaptive Frequency Drive)
Refrigeration (Cooling) Cycle
The refrigeration cycle of the chiller is conceptually similar to that of other Trane chiller products. It makes use of a
BPHE evaporator.
The compressor is a twin-rotor helical-rotary type. It uses a suction gas-cooled motor that operates at lower motor
temperatures under continuous full- and part-load operating conditions. An oil management system provides oil-free
refrigerant to the BPHE to maximize heat transfer performance, while providing lubrication and rotor sealing to the
compressor. The lubrication system ensures long compressor life and contributes to quiet operation.
Condensing is accomplished in BPHE.
Refrigerant is metered through the fl ow system using an electronic expansion valve that maximizes chiller effi ciency
at part load.
A unit-mounted starter AFD and control panel is provided on every chiller. Microprocessor-based unit control
modules (Tracer UC800) provide for accurate chilled BPHE water control as well as monitoring, protection and
adaptive limit functions. The "adaptive" nature of the controls intelligently prevents the chiller from operating
outside of its limits, or compensates for unusual operating conditions, while keeping the chiller running rather
than simply tripping due to a safety concern. When problems do occur, diagnostic messages assist the operator
in troubleshooting.
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