My time on Academic Study Leave learning Cable Jointing and Line Mechanic work with Connetics from February to July 2011 and the subsequent recovery and strengthening of the Christchurch power distribution network
Jointing 66kV cables for the reinforcing of the Christchurch distribution network
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Recently I had the opportunity to observe Shaun Baker and Barry Kelly jointing the 1000mm XLPE cable that is being laid to link the McFaddens Rd and Dallington Zone substations.
Shaun and Barry (as seen from my previous post's analysis ) have spent a lot of time in Christchurch jointing and terminating 66kV cables since the devastating February 2011 Christchurch Earthquake.
As is typical with all cable jointing, cleanliness is paramount, and the hole is contained inside a 22 foot container supplied by HV contractor Connetics. The container keeps dust and the weather out, and allows the jointers to work in relative privacy (except when being observed by certain Electrical tutors!).
The 'jointing container'
The interior of the container is powered and has block and tackle equipment mounted in it for ease of lifting the heavy cables into position.
The interior
The joint kit being utilised was a Pfisterer MSA 72-XKC. This is a kit utilising a silicon rubber slip-on joint rated at 72kV. The joint is fully contained in a protective housing filled with an insulating compound.
The procedure is exacting and tolerances down to 1mm are required for the joint to be assembled to Pfisterer's specifications.
The joint is started with cutting the cable to the correct length (I asked Shaun how they figure out exactly where to cut it, as this is crucial, and he responded that 'a lot of factors need to be taken into consideration". This is just one of many skills only mastered after years of experience in the trade.
Shaun cuts the cable while ensuring the strands are secured together
Barry strips the semiconductor and XLPE layers using a precision rotary stripping tool
The XLPE is then polished using progressively finer grit sandpaper
From this finish...
...to this finish....
...and rigorously inspected.
The cable is then protected for installation of the silicon rubber insulator. The insulator is a very tight squeeze, so lubricant and ratchet winches are employed (video later).
The insulator temporarily in place
The final 'lining-up'
And engagement onto the 'Mechanical torque control connector'.
Once in place, the connector's shear bolts are tightened using a battery driver, and than sheared off by hand.
The edges of the remaining shear bolts are deburred and plugs inserted. The silicon sleeve is then winched over the top of the connector.
The sleeve in place.
The earths of the cable are then connected. They are secured in place using heavy clamps and each end of the cable is earthed in a special box on the street.
Heavy earth clamps
Finishing up the earths
The two ends of the housing are brought together, then the filling compound is mixed and poured into the access holes.
Filling
Caps are put on and the joint is complete. The joints are encased in soft concrete with a red-coloured top layer.
The completed 3x joints
The earth bonding box
The red 'soft' concrete.
I would like to thank Shaun and Barry again for their cooperation in letting me observe their work. They really are a joy to watch, make an extremely technical, challenging job look easy, and are really nice guys.
Work log: Monday 21st March: Worked at North Parade, Shirley to repair a low voltage XLPE attached to a bridge for a private right-of-way that had been severely bent (but still operating ok, amazingly!) by the riverbanks 'slumping' in the earthquake 22nd Feburary. Slumping bending the low voltage XLPE Steve showing off the bent section Tuesday 22nd: QEII Drive near Marshlands Rd roundabout, XLPE-XLPE 11kV joint, network consolidation. Wednesday 23rd: Philpotts Rd near QEII Drive, XLPE 11kV termination into kiosk for network consolidation. Tightening 11kV terminations in kiosk Thursday 24th: Philpotts Rd again, more kiosk terminations and XLPE-PILCA joint. Finished kiosk terminations Friday 25th: Pages Road near bridge, PILCA-XLPE-PILCA faulty 11kV cable replacement. These rings are the modern alternative to lead wiping. Liquefaction causes the building to sink, pulling overhead connections off. Riverbank 'slumping', causing th...
Christchurch has had 3 major, 10 moderate, and around 7000 minor earthquakes and aftershocks at this point in time. The following is a personal account of the damage based on my personal experiences and the different side-effects of earthquakes. I need to stress at this point in time, I am NO geologist, seismologist, or network analyst. So some of this information may not be accurate, it's simply based on my logic as an Electrical Tutor! I apologize in advance if I say anything incorrect, and feel free to post anonymous comments (this has been done, already, thank you!) and correct me. In my opinion there have been four major side-effects of a quake (in Christchurch's case): Ground shaking Liquefaction Lateral spread L andslides/building collapse/rockfalls. Christchurch did not experience tsunami related to our own quakes at any stage. I will cover each category for some systems in the Christchurch distribution network that...
Well, I've finished with lines in the interim until later this month. In the meantime I'm going to be spending some time in 'Subs' and the 'Test room' Departments. Work log: Monday 2 May: SUBS; Brookside and Hororata Substations; repair design fault with approved manufacturer's rewire. Brookside substation Switchgear at Brookside substation Hororata Substation. The windows broken in the 4 September 2010 quake have been covered with wood. Tuesday 3 May: Wire control unit in workshop. Wednesday 4 May: Greendale Substation; Move and permanently wire communications unit. Greendale substation.. yes, it's practically on the fault line. Control units inside the substation Evidence of the explosion that occurred at the back of a circuit breaker during the M7.1 earthquake. Substation yard gates... do they line up?!! Thursday 5 May: TEST ROOM; Isolate and earth faulty 11kV cables, Opawa Rd bridge and near AMI stadium. Also rec...
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