Fuse protection of laterals in a unigrounded systems

[Mbrooke]

Ok- the specimen in question: a 13.8kv uni grounded system with all customers connected phase-phase. Do lateral taps need 3 phase devices or can fused cutouts do? A classical approach of 140Ts coming off the main trunk line, with 65T and 30T further branching off would be the most desirable. However my concern here is while a downed conductor will (can) blow associated cutouts keeping the main trunk energized, down conductors will continue to remain live from back feed.


I've heard second hand of utilities in California supposedly not fusing laterals for this very reasons (they use delta and uni-grounded).

 

[waross]

Considering the other advantages of re-closers, can you justify using re-closers on the branches?

Bill
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"Why not the best?"
Jimmy Carter

 

[Mbrooke]

I would need a lot of reclosers to cover all the laterals making it unlikely to be justified. Perhaps motorized switches in conjunction with feeder reclosers/breakers might be cheaper? Even then its looks like fuses.

 

[Mbrooke]

I guess the question is: is it acceptable to have full blow back feed during a down wire condition?

Second- if a fuse is blown, are there any over votlages that need to be worried about when opening the remaining two cut-outs or 3 phase gang switch out on the line? I want to make sure current interrupting is sufficient on such a system.