Preliminary design includes review and discussion of information necessary to begin design activities. Some of the items to be determined during preliminary design are as follows:
- Surveying needs for designing, verifying, and incorporating proper electrical clearances, spacing, and phasing
- Soil borings and geotechnical analysis required to support foundation design criteria
- Soil resistivity testing needs to support grounding design, ground grid modeling and safe step and touch potentials
- Begin procurements of the balance of necessary long-lead materials
- Relay requirements or detailed relaying specifications
Major Equipment Specifications & Procurement:
Realtime will review and comment on the client’s standard specifications for the major equipment. Realtime will provide all final specifications for procurement to the client. Changes or additions specified by the client will be incorporated into these documents, as well as client standard terms and conditions. Realtime will review and summarize all bids for equipment, prepare a detailed evaluation of each bid package, and if requested by the client, we will make recommendations for purchase to the client. Additional handling, review, and comment of vendor approval drawings are described in more detail below.
Detailed Physical Design:
- Site Plans – Realtime provides site development engineering, including detailed grading and drainage, cable trenches, and requirements for vehicular access. Our project teams are also very experienced in designing access roads, including requirements for surfacing and equipment access.
- Plan & Elevations – In addition to structure, insulator, equipment, and bus components, these drawings typically depict accurate locations for switch operators, conduit risers, junction boxes, and structure mounted lights, etc. Design and layouts by Realtime not only provide for the obvious requirements of electrical clearances and reliable service, but also consider all practical aspects of facility operation and maintenance. Spacing and layout for structures and equipment must allow for access by vehicles, booms, cranes, forklifts, or other equipment that may be needed to perform various O&M functions.
- Bus Designs – Realtime utilizes software to model rigid tubular bus systems as a standard component of the design process. Designs comply with ANSI/IEEE Standard 605 “Guide for Design of Substation Rigid-Bus Structures.” This software provides a graphical representation of the bus system, with each connection modeled as a) pinned, b) fixed for rotation, and/or c) fixed for movement in the vertical, horizontal, or transverse directions. The software produces output with stress limits, deflection, and required cantilever strength for each bus segment and support point. In lieu of visual analysis, Realtime can model bus design using StaadPro software.
- Cable, Conduit & Raceway Plans – Realtime will prepare cable & conduit layout and raceway details, as required, to result in an optimum value-engineered design for cable routing on a project. Although appearing to be simple in concept, the layout and design of cable raceway systems in stations can have major impacts on operation and maintenance of the facility. In addition, Realtime will determine the appropriate conductor sizes and configuration for control and fiber optic communications cabling, based on design requirements and client standards. The complete cable list required interconnecting all required equipment, panel boards, and major equipment will be prepared in standard client format.
- Control Building Layouts – Realtime’s project teams are well experienced with a large variety of control building designs.
Descriptions and quantities for major equipment will be added to the bus and equipment bill of materials drawing(s) to provide a complete list of all station components. This bill of material will provide complete descriptions and stock codes. Realtime will develop a detailed list of bus bill of materials items with quantities required to construct the tubular and cable bus system for the project. Complete bus details showing all required connectors, line hardware, assemblies, corona shielding, and associated construction requirements will be provided on bus details drawings.
Realtime’s Civil Engineers will be responsible for overseeing civil and structural design work for the project. Key components of foundation design would typically include:
- Foundation Plan(s)
- Foundation Sections and Details for Structures
- Foundation Sections and Details for Power Equipment
- Anchor Bolt Details
- Control Building Foundation
Realtime will prepare foundation plans that depict all required reinforced concrete foundations to support steel structures and equipment. Our team of structural/civil project personnel will prepare all foundation loadings, as well as all necessary foundation construction drawings.
Grounding Design – Realtime will design a new grounding system or add to existing grounding facilities, as required for the project. Soil resistivity values resulting from tests performed will be used in conjunction with ultimate short circuit capability of the system, fault clearing time, resistivity of finish rock surfacing, and other for system design. Using this basis for design, tolerable touch and step potentials will be calculated in accordance with IEEE Std. 80, and a grounding system will be designed to provide for personnel safety.
Protection and Control Design:
Realtime has extensive background in protection and auxiliary systems specification and design for substations and switchyards. Realtime is experienced with microprocessor-based solid state and electro-mechanical relaying systems, including ABB, Schweitzer, Basler, G.E., Alstom, (AREVA), Siemens, as well as others. Our engineering professionals are experienced in the application of a wide variety of carrier, RF, microwave, fiber optic, and satellite communications equipment. Realtime has provided design for a wide variety of analog and digital RF and microwave systems, utility-grade SONET, RFL and Iniven terminals, SEL communication processors, protocol converters, as well as a variety of other specialized communications equipment.
Realtime will prepare detailed layouts for control panels or racks, including physical placement, fabrication requirements, and device lists as a basis for bidding. Panel/rack elevation drawings will provide a high level of detail, including accurate dimensions for rack placement and/or panel cutouts. Complete device name, catalog number, and descriptions will be included on the drawings. A nameplate list including standard client terminology for all devices and switchyard equipment will also be prepared. Realtime will provide vendor interface, detailed bid evaluation, and recommendations for client approval.
SCADA, annunciation, transfer trip, and individual equipment indication points will be incorporated into the design. Concise lists of points will be developed and shown on the drawings for ease and interpretation during trouble-shooting activities. Realtime will prepare an implementation report to cover the varied aspects of controls and communications for the project – such report should include the following:
- RTU equipment requirements, rack design, protocol(s), I/O’s, and point lists
- Primary and alternate AC power supply and configuration, loading and short circuit study
- DC battery and charger sizing
- Voltage drop and ampacity calculations pertaining to all electrical equipment
- Outage requirements and construction sequencing for use in outage scheduling