With Carrier Transicold's new Advance microprocessor controller for trailer refrigeration units, ease of operation steps to the front for drivers and service technicians. Although the Advance is a highly complex design, it presents the simplest face possible to users.
Most notable is the fact that the new controller provides its information in plain language rather than code. Drivers and technicians no longer have to look up fault and codes in a service manual. The unit display panel states the situation clearly. In Europe, Advance speaks eight languages. For the present in North America, the new controller speaks English only.
The new controller will be offered on the Carrier Transicold Extra, the Ultra and Ultra XL, and the Ultima. It will not be available on the Optima, and it is not available as a retrofit for existing units. Deliveries of Advance will begin in 2000. By 2001, the new system is projected for at least 75 percent of Carrier Transicold's highway unit sales and should eventually be installed on 100 percent of deliveries, because it is expected that highway truckload carriers will adopt the new technology quickly. The next step in development will be a new controller for multi-temp units that should appear in 2001. Pricing for the Advance, which includes data recording, will be approximately $1,500 more than current controllers.
Rapid Pretrip Inspection The new Advance controller is designed to provide the reliability of marine containers with highway refrigeration units without the intensive maintenance expended on container units. In the marine container industry, every unit is given a thorough preventive maintenance inspection before every use, says Mark Cywilko, Carrier Transicold senior vice-president of Truck/Trailer North America. A container unit pretrip inspection typically takes four hours. New electronic routines in the Advance compresses this inspection process into eight minutes.
In addition to speed, the new system is more accurate than the same job performed manually. In the past, microprocessor controllers performed most of their checks using electronic sensors. The Advance actually measures pressure differentials across valves in the refrigeration circuit. A technician performing a pretrip inspection no longer needs to hook up pressure gauges to the refrigeration unit, says Neal Walsh, marketing director for truck and trailer products. "We imagine that technicians will still carry gauges and hook them up a few times when the equipment is new," he says, "but once they learn that the system is accurate, the gauges will stay in the tool box."
Advance steps forward in four areas, Carrier Transicold says. It is easy for the driver to use. It performs a complete pretrip maintenance inspection in eight minutes. It offers internal diagnostics to speed troubleshooting. And it collects data to aid fleet operators with their management.
30-Character Message Center For most operation, a driver has only one switch to operate. Once that switch is moved to the Start/Run position, information is available in plain language on a 30-character display screen. In addition, status lamps show unit operating status, and a temperature display provides actual box temperature and thermostat setpoint. If the setpoint needs changing or other programming is required, opening the controller exterior cover reveals a simple set of three control keys. These are clearly labeled in plain language rather than by using icons.
The controller communicates with the driver in English, not codes. If changes in unit operation, such as setpoint, are needed, the system prompts the driver with step-by-step instructions and gives a clear confirmation of the change. Driver control of the unit can be preprogrammed to lock out some functions to prevent accidental or intentional tampering with system operation. For instance, driver control of setpoint change can be limited to a specific range.
Advance offers more capability for service technicians, starting with the automated pretrip inspection. This routine runs 15 critical tests in eight minutes. During operation, sensors can record up to 150 diagnostic alarms to speed routine maintenance, troubleshooting, and repair. The system has built-in suction and discharge pressure transducers, an internal ammeter, and multiple temperature sensors. It also has a self-test circuit that causes a green indicator lamp to blink steadily once a second as long as the system is operating normally.
Mechanical Relays Eliminated Most of the mechanical relays in the system have been eliminated and replaced by field effect transistors. These SmartFET switches are more reliable than mechanical relays, because they sense open and closed circuits and shut off automatically to prevent heat damage, Walsh says. After incorporation of the SmartFETs into the Advance system, the unit controls contain only three mechanical relays and four fuses.
SmartFETs are an example of technology pulled from marine container units for highway unit use. These switches have no moving parts and are not a serviceable item. "After thousands of hours of testing, we've yet to see a failure," Walsh says.
Faults detected during operation are stored in memory when the unit is off. If the unit can operate safely, the driver can clear these alarms upon starting the system. This driver action does not remove the alarms from memory; it simply moves them to an inactive list for review by a technician.
One set of sensors is particularly important to unit operation. The Advance controller detects low refrigerant charge by measuring the pressure differential downstream and upstream from the compressor. It also compares the temperature differential across the evaporator coil.
Technicians do not have to run the entire pretrip routine to troubleshoot a unit. They can direct the Advance to test specific unit components and operating routines. The controller can energize unit circuits and troubleshoot the system without starting the unit. For enhanced troubleshooting, a technician can lock the system into specific operating modes and energize particular circuits in the search for malfunctions. This replaces trial-and-error troubleshooting with a logical process.
Advance has sensors for supply, return, and ambient air temperature; evaporator coil temperature; compressor suction and discharge temperature; compressor discharge and suction pressure; engine coolant level and temperature; battery voltage, engine rpm; oil and fuel levels; and engine oil pressure.
DataLink Standard With the Advance controller, Carrier Transicold has made its DataLink data recording system standard equipment. In addition, system memory has been increased to 512K-as much memory as that provided by relatively powerful desktop computers just a few years ago. While this may not seem like a lot of memory compared to systems that now routinely measure memory in 50 or more megabytes, it is still the largest memory available in a refrigeration unit controller-enough to hold four years of operating information.
Advance makes this information readily available to fleet managers without requiring the use of a PC or handheld data extraction device to download unit memory. With built-in DataShare, the Advance controller can transfer its entire memory onto a PCMCIA modem card in less than 30 seconds. One PCM card-slightly larger than a credit card-can hold all the data contained in seven refrigeration units. Thus, one card can hold up to 28 unit-years of operating data. Extracting data with the modem card simply copies the DataLink memory. It does not clear that memory. In addition to extracting data from the controller, the modem card can be used to load new software into the Advance.
Information from DataLink is analyzed using DataManager, a windows-based software package. This software allows managers to view or print data from the recording system. It also allows the user to customize controller software and install it using the modem card.
Six-Hour Meters Fleet operators can specify how data is collected by the Advance with six programmable hour meters. The display from these meters can be customized to meet individual fleet needs. The meters can be reset using the unit control panel.
Although Advance offers benefits to fleet operators, Carrier Transicold says that its primary benefits are ease of use by drivers and lowered service requirements by maintenance departments. The pretrip routine is designed to replicate the inspection a technician would perform. This has two advantages. First, a manual inspection that finds no faults still requires a great deal of technician time; so running the automatic inspection routine can save a great deal of maintenance department time. Second, any faults found are stored in memory, allowing the technician to start a repair immediately instead of spending more time on troubleshooting.
Both these advantages result in substantial savings in maintenance costs. One fleet that tested the Advance for Carrier Transicold suggested that the self-diagnostic features would save roughly three hours inspection and troubleshooting time per trailer per year for a fleet of more than 200 trailers. The cost saving was estimated to exceed $60,000 a year.
The Advance microprocessor moves refrigeration control systems beyond simply regulating temperature, Cywilko says. "It protects cargo as well as saving maintenance time and providing a large harvest of management information to its users," he says.