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Challenge:
A power company has had many problems with a mechanical control system which manipulates a large hydraulic valve. This valve regulates the flow of water through a Hydro-Electric power generator. As part of their plant modernization program, the customer wished to replace the old valve control system with a more reliable and more accurate system.
Valve Control Requirements
| Load |
1,200 lbs. |
| Speed |
1.8 in/sec |
| Duty Cycle |
50% |
| Repeatability |
±0.001 inches |
| Programmability |
Start-up Sequence
Shutdown
Sequence Run
Sequence
Emergency
Shutoff |
| Interface |
Stand-alone programming |
Solution:
| Control |
One-axis integrated servo control/drive |
| Actuators |
Electric cylinder |
| Accessories |
End-of-travel sensors |
The customer’s computer commanded the servo-controlled actuator to the proper valve position using discrete outputs. Since there was a large amount of electrical noise present, a self-contained control system was desired which did not rely on RS-232C or analog communication from the master computer. The cylinder's high speed and thrust ensure rapid response to changes in signal. Furthermore, in the event of system problems, an input was triggered, which runs and emergency shutdown procedure. High precision hydraulics were also considered. Because of the need to have an orderly shutdown in the event of hydraulic system failure, a separate power unit would have been needed. Furthermore, 0.001 inch repeatability proved to be difficult and costly to achieve. The controller’s easy-to-use motion programming, extensive I/O capability, and compact drive/ control/power supply package encouraged this customer to choose this solution.
Application Solutions
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