Advanced Controls
Trane set the standard for unit microprocessor controls in 1985 with the first generation Unit control panel. Associated with this standard have been:
•Proportional Integral Derivative (PID) control strategies which provide stable operation and higher accuracy for better performance;
•Adaptive Control™ to keep the chiller on line during adverse operating conditions and at the same time keep the chiller from a major failure;
•Software based safeties that do not depend on electromechanical hardware — hardware that means questionable reliability and added cost;
•Operator interface that accesses chiller information and control adjustments at the front of the panel.
Flexibility
UCP2 adds more flexibility, more reliability and better system performance than even our most demanding customers expect.
•The modular structure of UCP2 makes it possible for the designer to select the system controls and associated interfaces to Tracer™ (or other building automation systems) that are required for the chiller plant design. With this modular concept, capability can be added or upgraded at any time — with only temporary interruption of chilled water production.
•The operator can quickly program his Custom Report — so that only what is considered to be the most frequently accessed/important reports are available —at any time, right at the front of the panel.
•With easy front panel programmability of Daily, Service Start-up and Machine Configuration settings and setpoints, the operator, serviceman, and system designer can customize the use of the micro controller to the unique conditions of the chiller plant — whether the purpose of chilled water is for comfort cooling or for process cooling.
•All data that is necessary for the safe operation and easy serviceability of the chiller is provided as standard on all CenTraVac™ chillers. Options are available that provide additional controls/data that are required for:
an industrial/process system design, applications outside of the typical chilled water system design,
the need for redundant machine protection, or the desire for more system information.
•Equipment room refrigerant ppm monitoring can be integrated into the control panel by employing a chiller mounted monitor or a wall mounted monitor.
UCP2 is modular in design which offers the ability to adapt to changes easily and effectively without adding prohibitive cost. To provide flexibility, the controller responds to a wide variety of needs for:
System Designs including equipment, operating conditions, and controls variations that are either existing
or being considered for new installations.
Key to designing non-traditional systems is the ability to evaluate the cost and reliability issues of these systems in comparison to the more traditional systems. Trane recommends the use of C.D.S. Network Equipment Economics, the Trane Applications Manuals, and consultation with a Trane sales engineer for help in this analysis.
System Upgrades including the ability to accommodate changes in the chilled water system design or equipment room requirements or to accommodate new technologies that become available.
Reliability
To most people, reliability means
“dependable — giving the same result on successive trials.” However, to our customers it has come to mean “keep chilled water flowing.” In other words, “when I turn the switch on —cold water comes out.” In order to do this, the micro controller must be aware of what is happening in the system. But, more importantly, it must be able to make decisions and adjustments to keep the chiller running as long as possible even when non-standard conditions exist. Conditions such as bad power or bad water (flow, temperature, fouling) or system component failure.
•With Enhanced Adaptive Control™ the controller does everything it can to avoid taking the chiller off line:
—senses potential overload, freeze and condenser overpressure conditions
—displays a warning message about the potential condition/safety trip
—takes the following corrective action sequentially as the condition worsens:
limits loading
prevents further loading unloads until condition improves takes chiller off line
•With the ability to detect surge, UCP2 can call for corrective action to be taken to prevent a surge failure. If the system can respond within 15 minutes, the chiller will continue to operate until further corrective action can be taken.
•With the ability to function across a broader operating map, UCP2, in conjunction with the multiple-stage compressor, can provide safe operation when undesirable inputs to the chiller are encountered. This capability includes:
—cold condenser start
—running with hot condenser water
—low condenser water flow
—hot evaporator start
—varying water/fluid loop flow operation
—return from momentary power losses in less than one minute
—smart restart inhibit designed to get the chiller back on line fast
•With more diagnostics and diagnostic history that are time/date stamped and with help messages, the operator or serviceman can take faster and more effective corrective action.
•With the new stepper motor/inlet guide vane actuator, the same technology used in the machine tool industry offers highly reliable and precise inlet vane control.
Systems Performance
“Chilled Water System” encompasses many levels of control: Stand-alone Chiller, Chiller Plant, Applied System, Central Building Automation System.
