IEEE C37.95-2002 pdf download IEEE Guide for Protective Relaying of Utility-Consumer Interconnections
3. Establishing consumer service requirements and supply methods
3.1Interconnection
The utility-consumer interconnection provides the path for power flow between supplier (utility) and user(consumer). The interconnection may comprise one or more circuits and is assumed to include voltage transformation. For the purposes of this guide, the interconnection extends from the nearest source-sideprotective device used for switching on the transformer high-voltage side to the transformer low-side busand switching devices.
3.2 General design approach
The supply that is selected should satisfy the consumer’s load requirements. Available utility supply optionsin the area as well as the utility’s design standards and operation and maintenance practices should also be
considered.
3.21 Consumer’s load requirements
Prior to meeting with utility personnel, the consumer should define the present and future load requirementsincluding the connected kVA, the average load, and peak demand power requirements (both real and reactive). The effect of interruptions and voltage dips on plant operation, the required dependability and securityof the utility’s electrical service, and any other needs that may be unique to the operation should be deter.mined. The consumer’s engineer should be prepared to discuss these requirements in detail with utilityengineers to ensure that there is a clear understanding of the consumer’s requirements.
3.2.2 Utility service availability
The utility should describe the supply voltages available in the area and estimate the initial and total costs ofthe various alternatives. Most utilities establish nominal limits on the load that can be supplied at differentvoltage levels. The number of utility supply lines available and the performance level of each line should bediscussed in detail. In addition, the utility should inform the consumer of any required studies. unusual problems. or future plans that may affect the quality or continuity of service. Some utilities publish standardinformation booklets detailing the requirements for service.
When the consumer has identified critical power requirements, the utility engineer should investigate thescreguirements and be certain that both parties have a clear understanding of the effect of interruptions andvoltage dips. The utility may then be able to suggest a supply system that will meet these requirements, orsuggest plant control changes to make the operation more successful.
3.3 Information exchange
Once the supply method is established, a further exchange of inforation is required so that the stationdesign can be completed and the utility can make the necessary preparations to supply the service. By estabishing good communication between the utility and the consumer as early as possible, specific requirementsfor either a new or modified supply can be identified and included in the initial design before equipment isordered.
3.3.1 Typical information furnished by utility
Available utility short-circuit current,including values for normal and altemate supply facilities, as2well as any anticipated future values (i.e, range of single and three phase-to-ground fault currents.and associated X/R ratios, at the consumer’s point of service)Expected minimum,maximum, and nominal voltage at the consumer’s point of service for availablevoltage levels
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Outage history of the supply, including both forced and maintenance outagesC
IEEE C37.95-2002 pdf download
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