Did a bit of digging today.

[Knobhead]

How did you go on with this escapade? Everything back to normal yet?

 

[Bobster]

Well the fault wasn't in the joint box (unsure why the thumper detected a fault now. Will investigate later)

I have got pics of the cable cut after spiking and the terminations in the switch gear I will upload when I get a min.

Thats as far as this jobs gotten so far It's fallen by the wayside a bit. Monday we had a peice of brand new 11kv switch gear explode so I've been investigating that. Fingers crossed it hasn't damaged our 12MVA transformer.

I have pics of this I will upload at the same time. I'll start a new thread with it though.

 

[SPARTYKUS]

Well the fault wasn't in the joint box (unsure why the thumper detected a fault now. Will investigate later)

I have got pics of the cable cut after spiking and the terminations in the switch gear I will upload when I get a min.

Thats as far as this jobs gotten so far It's fallen by the wayside a bit. Monday we had a peice of brand new 11kv switch gear explode so I've been investigating that. Fingers crossed it hasn't damaged our 12MVA transformer.

I have pics of this I will upload at the same time. I'll start a new thread with it though.

The City & Guilds 6037 ​looks an interesting one!

 

[Bobster]

 

[Bobster]

Just to explain the pictures. The terminations that are unbolted are the faulty cable. The terminations behind these are the cable to the right of the one that's been cut in the picture above.

We have the two cables in parallel.

 

[Bobster]

The City & Guilds 6037 ​looks an interesting one!

Bloody long exams. 4hour written 4hour practical.

 

[mogga]

where are you from ROB??

 

[Bobster]

From the north west near Blackburn.

 

[Engineer54]

Just to explain the pictures. The terminations that are unbolted are the faulty cable. The terminations behind these are the cable to the right of the one that's been cut in the picture above.

We have the two cables in parallel.

I've never seen so much copper showing on 11KV cable lug terminations. I always like to see, and insist on the lug butting up to the insulation, and at the very least heatshrink upto the bolted section of the lug. All our MV cable terminations are fully booted after all testing has been completed, but that wouldn't be possible with this termination arrangement.

The photo maybe deceiving, but the distances between those termination plates seem awful close to me for 11KV, especially when bare, (un-booted or insulated)

 

[SPARTYKUS]

Bloody long exams. 4hour written 4hour practical.

Closed book I expect as well. Proper exam.

 

[Knobhead]

Got to agree with E54, there’s far to much bare copper for my liking. Plus all the corners of the link plates should be rounded.
What’s the transformer rating 11/3.3KV maybe? Even 3.3 would need some hellish switch gear. 12MVA @ 3.3 = 2099A

 

[Bobster]

There insulated with a very viscous oil. This is why the gaps are so close. That what the brown liquid is at the bottom.


Answer to the other question yes closed book exam.

Edit: Tony it's an 11/3.3 the fault occurred on the secondary side. We dipped peoples lights at home up to 13miles away when the fault occurred. Glad I wasn't there.

 

[Knobhead]

One thing I do like is the lugs are sweated brass. It’s awhile since I’ve done them!

 

[Knobhead]

Just had a real close look at the terminal box. They look like PILC screened cables. To me the stress relief is no where near long enough, but it’s not failed there so must have been OK. I would normally take the stress relief about 60mm beyond the lead.

 

[Bobster]

To be honest Tony I haven't ever worked with oil filled termination boxes before. These have been installed 20years according to documentation I've found and has never been a problem.

With this switchgear fault we have had on site the cable fault discussed above has been put on the back burner for the time being.

I'd like to share more information about the switchgear fault but the cause still hasn't been identified and this is a public forum, I wouldn't feel right posting what could turn out to be fairly sensitive information.