Create guidelines specifying the maximum cable length which can be switched for the following types of transformers without excessive overvoltage.
- delta primary three-phase padmount transformer
- grounded-wye primary three-phase transformers having amorphous metal cores
- grounded-wye primary three-phase transformers having five-leg stacked cores.
Determine the capability of metal-oxide surge arresters to survive exposure to ferroresonant overvoltage caused by the interaction of three-phase grounded-wye padmount transformers and URD cable capacitance. Create guidelines indicating the maximum cable length which can be switched with a transformer, in terms of the arrester type, arrester voltage rating, and system voltage class.Read More →
Extend the research performed in Phase 1B to perform a more in-depth evaluation of arrester survivability when exposed to amorphous-core three-phase transformer ferroresonance, and in particular to assess the performance of under-oil arresters in this condition. Create guidelines indicating the range of application parameters for which an under-oil arrester can be expected to survive extended exposure to amorphous transformer ferroresonance.Read More →
Measure the resistance of a diverse group of single and three phase distribution transformers from 60 Hz to 1500 Hz. Develop tables which indicate permissible harmonic loads for the folloowing load combinations:
- 60 Hz and 6 pulse drives
- 60 Hz and 12 pulse drives
- 60 Hz and switch mode power supplies
- 60 Hz and compact fluorescent lighting
Develop Analytic Models to investigate lightning-induced surges on distribution secondaries. Determine which system parameters have the greatest effect on the first layer voltage in distribution transformers. Develop a spreadsheet which calculates the overvoltage performance of 10 and 25 kVA transformers for rural and residential circuits over a range of pole ground resistances.Read More →