Section VIII - Power$ync II™ Operation
Network Load Delay Time
In multiple machine network applications, control is passed from machine to machine based on the programmed sequence. In the sequence ‘ABCD’, the ‘A’ machine is the base machine and the ‘D’ machine starts with the pointer. If the system demand for air drops, the ‘D’ machine will pass the pointer to the ‘C’ machine. Further reductions in system demand may trigger the ‘C’ machine to pass the pointer to the ‘B’ machine. An increase in demand would cause the pointer to be passed back to ‘C’ and then back to ‘D’.
When the demand is decreasing, the machine with the pointer passes that control to the next machine in the sequence when it has unloaded and the system pressure is still trying to climb. After a machine has transferred the pointer, it will completely unload, start its shutdown timer and turn itself off.
When the demand is increasing, the load delay time setting allows the controller to wait the programmed number of seconds before loading up, or starting the next machine down the list due to a pressure drop of short duration.
Pressure Settings
NOTE
The following explanation applies to single machine applications and to the base load machine in multiple machine applications. Trim machines, in multiple machine applications, will be held to their assigned pressure bands.
The load pressure is the maximum pressure at which the machine will operate at full capacity. As the demand for air drops, the pressure will rise to the unload pressure. At the unload pressure, all Power$ync II™ valves will open.
At this point, the compressor will not be compressing air. The maximum load and unload pressures are determined by the available motor horsepower and the pressure ratings of various components in the compressor package. The technical data sheets for the individual compressor models show this maximum number.
The differential between the load pressure and the unload pressure cannot be set to less than 5 PSIG. At the maximum setting for both load and unload pressures, the differential will be 15 PSIG. At the minimum load setting (75 PSIG) and the maximum unload setting (125 PSIG, for example), the differential can be great.
To determine the proper pressure and differential settings, several factors must be considered. The first consideration is the actual pressure required in the plant air distribution system to maintain proper equipment performance. For maximum energy efficiency, do not maintain more pressure in the system than is required. Almost all systems have some leaks. More air will pass through a leak at a higher pressure than at a lower pressure. Many pneumatic tools and devices are rated to operate at a particular pressure. Operating them at a higher pressure increases the amount of air that they consume. Increasing the pressure by ten percent will increase the volume consumed by the system by a proportional amount without an associated increase in productivity. It is prudent, therefore, to maintain the lowest system pressure that provides efficient tool and device performance.
The second consideration is the storage capability of the distribution system. A distribution system with little or no storage capacity will operate better with a wider differential between load pressure and unload pressure. Systems that have more compressed air storage capacity (three gallons per cubic foot of compressor capacity or better) can improve compressor energy consumption by using a more narrow pressure differential. The benefit of having adequate storage capacity is a more consistent system pressure and smoother operation of equipment. The differential should be initially set at 15 PSIG. If the system pressure remains steady throughout a typical work cycle, the differential can be reduced to as low as 5 PSIG. If the system pressure fluctuates greatly at 15 PSIG, indicating little system storage capacity, the differential may need to be broadened.
34 | Quincy Compressor® - QSD™ |
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