|
Program
5
5-1 Elbow Switching Capabilities for Unloaded Cable
Identify the phenomenon or phenomena responsible for
unexplained flashovers of elbow terminators, while switching unloaded or very lightly
loaded distribution cables. Also, correlate these switching failures to system (e.g. cable
length, circuit topology) and component (e.g. elbow and bushing insert) characteristics.
Two stages of investigation are planned:
- Failure mechanisms will be identified in laboratory
re-creations of typical field operations
- Insulation strength will be defined for varying positions
and environmental conditions.
In addition, this effort will be continued in Program 6,
where a switching performance test will be developed and recommended for incorporation
into ANSI Standard 386.
Deliverable: Investigations of Elbow and
Insulated Cap Flashovers, joint final report for Projects 5-1 and 6-1, 9/97.
5-2 Floating Wye-Delta Overhead Bank Overvoltages
Investigate and quantify overvoltages produced by
floating-wye delta overhead transformer banks when switched or following fuse operation,
and investigate the ability of arresters to withstand these overvoltages. Generate
explicit recommendations on the application, overvoltage protection, and operating
procedures for these banks.
Deliverable: Wye-Delta Overhead Bank
Overvoltages, final report 1/96.
5-3 Gapped MOV Arrester Characteristics
Compare the protective performance of gapped and gapless
distribution MOV arresters under the following non-standard conditions:
- wide range of rise times
- multiple impulses in succession
- bipolar impulses
Interpret the impact of any differences on equipment
protection.
Deliverable: Comparison of Gapped and
Gapless MOV Arrester Characteristics final report 5/95.
5-4
Software Development for the Analysis of Cold Load Pickup
Develop a tool which can be used by DSTAR engineers to aid
in the determination of cold load pickup currents and selection of fuse ratings based on
these currents. Standardized computational techniques will be incorporated in a
spreadsheet form. Two modes of operation will be possible:
- Generic approximations, from simplified load responses
and user-specified feeder characteristics
- Cumulative feeder response, when detailed loading data is
available.
Deliverables: Cold Load Pickup Spreadsheet
(EXCEL and Lotus versions) 5/97; CLPUSS User’s Manual 5/97.
5-5 Transformer Owning Cost Software
Develop a program to evaluate and optimize the lifetime
cost of owning and operating distribution transformers. This tool will estimate the
service life of specific distribution transfomers under various overload duties, and will
project the cost of owning and operating those transformers.
The approach will be general enough to accomodate
individual utility practices, yet will apply standardized computational techniques. The
program will be able to handle either default or user-specified thermal and economic
parameters, and will include the option to correct for harmonic loading.
Deliverables:
5-6 Service Entrance Protection Coordination
Investigate arrester application issues at secondary
service entrances, specifically with regard to the overvoltage coordination between
service entrance arresters and utility equipment. The results will:
- Define whether service entrance protection may be applied
without performaing secondary surge mitigation.
- Specify any steps needed to counteract an increase in
utility equipment stress.
- Indicate the application circumstances (e.g. grounding
conditions, transformer type) where mitigation is necessary.
Deliverable: Service Entrance Protection
Coordination, final report, 11/96.
|
