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Criteria for Design and Specification. Discussion at CPAC / NeSSI Regarding NeSSI Generation 2 Bus November, 8, 2007 Bob Farmer. Topics. Overview; terminology Criteria regarding bus and system Criteria regarding components and component parts. T. V. P. A.
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Criteria for Design and Specification Discussion at CPAC / NeSSIRegarding NeSSI Generation 2 Bus November, 8, 2007Bob Farmer
Topics • Overview; terminology • Criteria regarding bus and system • Criteria regarding components and component parts
T V P A Basic Bus Configuration and System Concept Controlling Unit (SAM) B B B B
T V P A Extended System Concept Controlling Unit (SAM) ? B B B B AC Power ? DC Power
T V P A Extended System Concept Ambient Environment Cabinet System Environment Controlling Unit (SAM) B B B B B B AC Power DC Power
Bus including drivers and power source Bus Definition Substrate Definition Point of Bus Interface Point of Substrate Interface NeSSI Substrates by: Swagelok, Parker or CIRCOR Component Electrical Implementation Bus electronics; Intrinsic Safety barriers; and Standardized interface to component electronics SAM – including Bus source and software Proprietary component-specific electronics by component vendor Proprietary mechanical NeSSI component by component vendors Assembly and certification of the complete component
Conditions To Be Considered In Bus Design • Overall system configuration and size • Minimum • Typical • Maximum • Ambient environment • Impact on bus external to system enclosure • System environment • Impact on bus internal to system enclosure • Impact on components and devices in system • Component capabilities and requirements • Power issues • Native capabilities and implementation methods regarding safety concerns • Market volume: available development resource commitment and impact on bus interface development
Bus Design Criteria Power Requirements: Sensors: 10-40ma Controllers: 20-70ma Valve pilots: 80-350ma • Capacity • Number of devices • Types of devices • Participating suppliers • Physical Issues / Installation • IP ratings / protection • Ambient conditions • Certifications / safety • Chemical resistance • Electrical • Length • Installed base / compatibility • Load capacity / load management • Power distribution • Interruption / interchange • Reliability / EMI / RFI • Instances / continuity • Software • Device representation • Device function • Maintenance issues • Configuration / addressing / identity Number of components on bus: Typical: 5-15 Common: 20-30 Maxum: 200 Design goal for flammability ignition temperature to be T4 (135°C) with minimum at least T3 (200°C). Component ambient temperature to be >=70°C Capability for the standard functions to be implemented in a variety of ways.
Cabling Issues • Cable size, bend radius, height • Connection methods and system design • Jacket materials • Cost
Other Product Marketability Issues • System responsibility • Supplier: Integrator, component manufacturer, bus provider • System elements: Bus master, components, cables and peripherals • Field support • Training • Configuration and implementation difficulties • Issues with interchangeability • Spare parts and long term support • Field diagnosis and repair plan • Component support life: longevity in a “capital” investment versus short life span of electronic and software techniques