Table of Contents
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(1) Introduction
The following information describes the Trane
microprocessor based absorption control panel (UCP =
Unit Control Panel). This section details the control
strategies designed to ensure a more reliable and efficient
chiller operation. Limit modes provide functional but
limited machine operation to avoid any safety shutdown,
therefore; keeping the chiller on line. When a safety
condition is actually violated, the UCP safeties provide
protection to the machine and personnel by terminating
machine operation. Proportional, Integral, and Derivative
(PID) lithium bromide concentration control provides for
stable and efficient machine performance. Reduced cooling
water temperatures to 65°F, when available, can further
improve machine efficiency.
The controls discussion within the operation maintenance
manual has owner level information that is not repeated
here. The content of this section is service level oriented.
Therefore, knowledge of the operation and maintenance
material is important for a complete understanding of this
control system. Review and understand the information in
this manual before troubleshooting or startup is attempted.
Manual Layout
The table of contents outline the topics covered.
The following are the major sections:
Absorption Cycle (Section 2) - This section covers the
basics of the solution cycle; how the refrigerant and lithium
bromide flows through the chiller. An understanding of the
absorption cycle is necessary to follow how the lithium
bromide cycle is controlled by the Unit Control Panel (UCP).
Sequence of Operation (Section 3) - The microprocessor
has a programmed sequence for machine startup,
shutdown, operating limit and safety shutdown. This
section describes these events in the sequence.
Control Panel Layout (Section 4) - This section provides
control type and location information within the unit
control panel.
Clear Language Display (CLD) (Section 5) - The (CLD) is the
device that allows the operator to communicate with the
machine. The details include how to use it and information
on reports, settings and functional keys.
Sensors and Controls (Section 6) - Various temperature
sensors and machine-mounted controls connect to the
control panel. This section explains the type and purpose of
all sensors and controls that are connected to the UCP.
Control Strategy (Section 7) - The control system objective
and strategy is discussed along with limit and shutdown
methods.
Limits and Safeties (Sections 8 - 20) - These sections
explain the limit and safety function of the UCP and how
they may affect machine operation. The limits provide
protection for the chiller to overcome transient operating
conditions.
Purge System (Section 21) - This section explains the
theory and operation of the Purifier Purge including the
setpoints, inputs, outputs, operating modes, operation
status and timers.
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