Main panel components

• Allen-Bradley programmable controller with expandable I/O
• Allen-Bradley Panelview
• Analog module

Interface panel components

• Inlet/Outlet numbered terminal strips
• Low voltage relays for command signals
• Low/High voltage relays to isolate control voltage.
• Local/Remote selector switch

Program Routines

• LIFO Last in First out
• FIFO First in First out
• Base Full load operation
• Trim One machine will load and unload during most system changes

The automation system is capable of controlling up to six compressors and will connect with the compressor interface panels via 24-volt dc wiring. It is upgradeable to communication with external information platforms.

The base program will be capable of controlling six two-step compressors and the operator can select either base or trim mode for each compressor. The sequence rotation can be LIFO or FIFO for base or trim compressors. Some examples are: the base rotation could be FIFO and the trim rotation could be LIFO; or, the base rotation could be LIFO and the trim rotation could be FIFO.

The system uses a Panelview 550 for human interface. The operator will have a compressor set-up screen for each compressor. This screen is used to select many options during the initial set-up to reduce the need for on-line programming changes. Also the two-step interface panels use double pole relays that can be easily changed to assist in the automation set-up. Each compressor will have its own screen to view its running hours and current status. Current status can include, but is not limited to, base or trim mode and loaded or unloaded.

The program logic can start/stop load/unload all compressors placed in automation and determine which compressors are available by monitoring compressor control voltage. The program will display on the Panelview if a compressor is running or off, loaded or unloaded, available or unavailable, compressor controlled or PLC controlled. The PLC will attempt up to two cold starts on a compressor and, if a running feedback is not sensed, display a failure to start alarm and move on to the next available compressor. An alarm will also be displayed if a compressor is given a signal to load and no feedback is sensed. Storage pressure in psig will also be displayed on the overview screen.

In the event of a PLC failure, the compressors under automation (remote) will be released to their local controls.

The customer portion of the automation installation is simple and safe. The main automation panel must be mounted at operator level in a clean location. Interface panels are installed at or near each compressor. The longest wiring runs between the main automation panel and the interface panels are low voltage and do not require conduit. The shorter wiring runs between the interface panels and the local compressor panel must be run in conduit as the control voltage is normally 110V or higher. In an effort to save installation dollars, the customer can terminate low voltage wires. A factory technician should terminate high voltage wires.

At the completion of the start up, the customer is trained in the operation of the system and operation and maintenance manuals are provided.