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
Far out time's going fast on this ASL (academic study leave)! Week 3 over!
This week's log:
Monday: Halswell Junction Road with Jamie. 11kV XLPE-HDPE (high density polyethylene), spiked.
Good 'spike'.. right through!
Tuesday: Orion EAC (entry approval certificate) course in the morning at CPIT Tradefit, afternoon Ensors Road with CJ and Nick to break into a 11kV PILCA with two XLPE for a kiosk.
Steve shows CPIT students the inside of a kiosk
Wednesday: Timaru with John, Terry, and Mark to do 33kV 1200mm2 3x single core XLPE.
Ends prepared for joining
Thursday: CPIT tradefit sub terminations with Steve.
Friday: Halswell Junction Road 11kV XLPE-PILCA with Steve
Analysis:
33,000 volt joining in Timaru
On Wednesday I travelled to Timaru to see John, Terry and Mark joining 33kV cables for Alpine Energy. Cables come in drums of (?) length, and need to be joined the length of the full (?) run to a new substation.
The joining is done deep underground, under all other services. Connetics use a open-bottomed container as weatherproofing and for protection of the jointers.
The 'joining container'
The cables are 3x single 1200mm2 aluminium with neutral screen XLPE and MDPE (medium density polyethylene). Alpine's specification was to use crimp joiners rather than the newer 'shear bolt' joiners.
Cable description on side
1200mm2 aluminium 33kV cable
Both ends of the 33kV cable are stripped and prepared with the minimum wastage possible. They are measured and aligned for joining.
Stripped and ready for joining
The joint is performed using a large hydraulic crimper, which is a very flash and expensive piece of equipment! The cable is stripped back to measurements specified by the joint manufacturer, with the usual extra care for the semiconductor layer. Correct measurements are crucial to this operation, with no room for error (no pressure!).
Crimping done
John would like to lay claim to his 'John's jack system', which ensures the crimper is always at the correct height using a heavy duty hydraulic vehicle jack! Brilliance!
John's jack!
John in action
Seeing John and Terry (the joiner guru!) in action was great!
I travelled back, pausing at Highfield Road to stand on the Greendale fault, the cause of out M7.1 quake and $5,000,000,000 of damage in Canterbury. Kinda odd that Highfield Road is next to fields that have been pushed up... High.. sad I know...!
On Highfield Road, the Greendale fault line
Postscript.. NOTE: This is still before 22nd February. Post-quake coming soon.
Hazards
The following hazards are associated with cable jointing:
Electricity (obviously!) in kiosks and nearby cables
Open flame/heat when heating cables for stripping and when heating heat shrink
External noise and the driver for shearbolts
Tools/sharp ones in particular for stripping
Other contractors/public (including 'rubberneckers', which there are a surprising amount of!)
Vehicles/heavy and diggers etc.
Weather wind/sun/rain
Dust, when windy
Fumes from heating pitch in PILCA cables
Oils on PILCA cables
Sharp edges
Holes/cave ins
Kiosk and sub doors
Dehydration
Lead poisoning
Slips
Teaching methods for hazards:
Brainstorming - drawing on previous knowledge of students
Practical (individuals or teams depending on formative or summative assessment)
Scenario work - field trip or photos/video (moodle?)
The semiconductor layer
The semiconductor layer is a thin layer in HV cables that usually surrounds the immediate first conductor insulation layer (usually XLPE). The function of the semiconductor layer is to 'spread the charge' if the XLPE layer fails insulation-wise. Special tools are used to strip the semiconductor layer carefully and NOT damage the XLPE layer. This layer is a modern measure used on HV cables. A special 'strip tool' is used to strip the semiconductor layer nicely without damaging the XLPE layer.
Next time: The 'block' starting 21st February to 17th March. Apologies due to delay caused by the February 22nd Magnitude 6.3 Christchurch earthquake which devastated Christchurch and killed hundreds. RIP the 'unlucky ones'.
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 were affected, namely: Substations
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
Comments
will look forward to reading your 21/2 to 17/3 blog :)
Good to know you are well and I am sure very very busy with all the work the 22/2 earthquake has produced.
Keep up the good work, Selena
Thanks! Yes, we've been very busy!
Working on the 'gap' now!