Overhead Riser Pole Protection Practices

[saladhawks]

I have a question about system protection related to primary overhead riser poles served upfeed from underground vaults. The standard engineering practice at the utility I work for is to install fused cutouts on all primary upfeed riser poles serving overhead laterals. The riser pole upfeed originates from underground vaults via manually operated solid-dielectric switches (no fault interruption capabilities).

Recently, there have been a high number of animal contact incidents on the line side of riser pole fused cutouts. These faults have been cleared by the substation breaker resulting in a total circuit outage. Internal discussions have been initiated to replace the underground manually operated solid-dielectric switch with an underground resettable fault interrupter (RFI) in order to protect against similar future animal contact incidents.

My opinion is that the line side of the riser pole fused cutouts should include animal protection elements (i.e. insulated coverings, anti-perch guards, squirrel guards, etc.) and that it is overkill to install an underground resettable fault interrupter (RFI) for each upfeed riser pole serving an overhead lateral.

What system protection practices are being followed by other utilities to prevent similar outages due to animal contact on the line side of riser pole fused cutouts?

 

[alehman]

So why do think you are having a lot of animal faults on the line side of the fuses? Do you have animal faults on fuses for underground customer services? There are lots of animal guard products on the market. You might consult a company that make such things.

In my area it is most common to have one feeder riser pole per underground circuit with non-fused switches on the pole and overcurrent protection only at the substation.

 

[apowerengr]

It sounds like your question is based on a conflict between eliminating the cause of the outage or minimizing the consequences. Apparently others don't believe the source can not be effectively eliminated - do you agree? Animal guards in various configurations would be standard with the many utilities I work with in the US. As for your comment about "overkill" I suppose it depends on how much of your annual incentive/bonus is based on these feeder-level outages vs. how much money is left in the budget and whom (CEO) is asking for the solution?

 

[Morrand]

I agree that the interrupters are overkill if the laterals are already fused. Animal guards may work, or more likely you need to reevaluate your cable pole construction standards/practices to reduce the potential for animal contacts. What two points are the animals contacting to fault the circuit, and can they be separated effectively?