Program 5

Project 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.

Tagged: P1-5, P5, Equipment Testing/Evaluation, System Protection, Engineering Guidelines, Engineering Analysis Software, Economic Analysis

Project 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.

Tagged: P2-5, P5, Equipment Testing/Evaluation, System Protection, Engineering Guidelines, Engineering Analysis Software, Economic Analysis

Project 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.

Tagged: P3-5, P5, Equipment Testing/Evaluation, System Protection, Engineering Guidelines, Engineering Analysis Software, Economic Analysis

Project 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.

Tagged: P4-5, P5, Equipment Testing/Evaluation, System Protection, Engineering Guidelines, Engineering Analysis Software, Economic Analysis

Project 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 transformers under various overload duties, and will project the cost of owning and operating those transformers.

The approach will be general enough to accommodate 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.

Tagged: P5-5, P5, Equipment Testing/Evaluation, System Protection, Engineering Guidelines, Engineering Analysis Software, Economic Analysis

Project 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 performing 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.

Tagged: P6-5, P5, Equipment Testing/Evaluation, System Protection, Engineering Guidelines, Engineering Analysis Software, Economic Analysis