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CURRENT LIMITING FUSES FOR OVERHEAD TRANSFORMERS. Why consider current limiting fuses?. Originally a question on overhead transformer fusing. Led to a suggestion to investigate using smaller fuses to limit oil spills from overhead transformers.
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Why consider current limiting fuses? Originally a question on overhead transformer fusing. Led to a suggestion to investigate using smaller fuses to limit oil spills from overhead transformers. Evolved into a suggestion to utilize current limiting fuses to limit oil spills from internal faults in overhead transformers.
Oil Spills- Causes • Year Overload Internal Fault • 2003 273 133 • 2002 152 147 • 2001 122 124
Current Limiting Fuses Looked at utilizing Cooper NXII CL fuse mounted either at the cutout or on the transformer. Cost ranged from approximately: $ 25/ for up to 12 amp $ 30/ for 15- 25 amp $ 40/ for 30- 40 amp
Survey • Informal survey of SWEDE and EEI member companies. • Only three respondents used current limiting fuses for overhead transformers (CPS, Centerpoint & Exelon). • Among reasons cited included controlling catastrophic failures.
Findings • Current Limiting fuse could alleviate some oil spills due to internal fault. • Number would be limited. • Fault Current limited by reactors • Dependent on degree of protection • The cost of adding CL fuses to all overhead units was greater than the anticipated cost of oil spills. • Possible operating issues.