Substation transformer MV connection taping

[dsdudash]

What determines when and how a medium voltage (say, 5 kV - 34.5 kV) shielded cable connection gets taped? Assuming the cable has a Raychem or 3M stress cone installed, is taping the bolted connection at the transformer bushing necesary, or recommended by any standards?

 

[magoo2]

I don't believe it's covered by any standards. We tape them for reducing the chance of a flash due to wildlife.

 

[Marmite]

It depends on the system BIL and the clearances phase-phase and phase-earth in the cable box. There are standards, for example in the UK we have BS164. These days you can use polymeric bushing boots as an alternative to tape.
Regards
Marmite

 

[oldfieldguy]

I'll second "magoo2"'s comment. Plus, the tape job serves to protect the connection from corrosion.

Marmite's comment about the boots points out a neat alternative. You can order, employ and reuse the boots.

We still recommend a couple of passes of vinyl tape under the boot, concession to that corrosion problem, but I used to work in a lot or petrochemical plants that were subject to some corrosive atmospheres.

old field guy

 

[dpmac]

It always seemed odd to me that MV Metal Clad switchgear has specific bus bar insulation requirements for all the obvious reasons but I could never find anything written that required the same level of insulation at the load side cable termination points. Seems nowadays the clearances are so tight in most modern MV Metal Clad switchgear that load cable taping/boots is a must.