Trane

Design a production line test facility for a commercial HVAC compressor. The test facility must:

• Allow for the testing of a range of power ratings (3000 to 14000 watts)
• Verify the wiring and parametric values of the electrical motor
• Verify the integrity of the compressor’s check valve
• Operate the compressor and verify the power and massflow performance is within limits
• Communicate with the assembly line conveyor to control flow of the product
• Communicate with the assembly line to retrieve the model # of the product to be tested
• Communicate with a network database to retrieve all the required test limits
• Communicate with a network database the measured results of the product tested

The design required sophisticated electrical mechanical power control, precise instrumentation, reliable test algorithms, the ability to communicate with multiple networks, and most importantly, the ability to be run by an operator with minimum training. This mandated a design approach that would divide the required functionality into two separate computerized test products.
To accomplish the electrical mechanical control, we designed half the system around an Allen-Bradley PLC-5. This gave us the ability to ensure reliable and repeatable operations. All product testing algorithms as well as personnel safety algorithms were implemented in ladder logic on the PLC-5. The PLC-5 also provided us with the capability of communicating with the DH+ network used by the assembly line conveyor.
To allow for simplified operator usage, the ability to communicate with network databases, and to provide for interface to high precision instrumentation, we designed the second half of the system around a PC. The PC needed to connect to three different networks:

• A DH+ network to communicate with the PLC-5
• A HPIB network to communicate with the instrumentation
• An Ethernet network to communicate with the network databases

The resulting design was one in which the operator interacted with the system via a Visual Basic application running on the PC. The PC would coordinate information flow throughout the test station and the factory's network database. The PLC would (when requested by the PC) run the various test algorithms.

The system met and exceeded all customer expectations.

VB 5.0
Access 97
AB PLC-5
AB NIS cards for high precision analog inputs
HPIB Powermeter (Yokogawa 2533E)
HPIB 4 (HP34401A)

Cle Wackerbarth (608)787-2882