دانلود رایگان مقاله طراحی به کمک کامپیوتر (CAD) سیار با روش شی گرا برای کنترل برق

Abstract

The quality of computer-aided-design (CAD) generated ‘As-built’ documentation is evaluated for a High Voltage Switchgear System (HVSS), which forms part of a Supervisory Control and Data Acquisition upgrade within a geo-thermal power plant. A total of 267 CAD drawings for the HVSS were used to create a Systems Information Model (SIM) whereby the physical components and associated connections were constructed in an object orientated database. Throughout the modelling process a considerable amount of errors and information redundancy were identified and examples are presented. The production of the CAD drawings took 10,680 man-h in stark contrast to the 80 man-h required to construct the SIM, illustrating the efficiency and effectiveness of SIM compared to CAD for the documentation of electrical instrumentation and control systems (EICS). To realise this significant potential cost and productivity saving requires a shift in mindset and a move beyond the use of CAD, to an object oriented SIM, with a 1:1 relationship between objects in the model, and components in the real world.

7. Conclusion

Despite software advances that have materialized to enable the use of BIM within the architectural, structural, heating ventilation and air conditioning, and hydraulic arenas, there has been a proclivity for EICS engineers and draftsman to use CAD. This has caused significant problems for large engineering projects, as CAD is used to produce paper-based outputs that have propensity to contain errors, omissions and redundant information. Moreover, at a project’s practical completion masses of ‘As-built’ drawings will be handed over to an asset owner for use during operations and maintenance. When errors and omissions are present then an asset’s integrity is adversely impacted. To examine the extent of this problem, the quality of the ‘As-built’ documentation produced using CAD for a HVSS, which formed part of an up-grade of a SCADA for a geo-thermal power plant was evaluated. A total of 267 CAD drawings were examined for their errors and information redundancy and then used to create a SIM. At this juncture, it needs to be made explicit that the SIM was created from existing CAD documentation that had been provided and that the nature of engineering design was not considered.