Thursday, June 9, 2011

Week 18; The relocation of New Brighton substation to Rawhiti substation.

This week I observed the finishing of the circuit which is an extension of the original 'emergency circuit' that Orion, Connetics, Independent Lines, and Mainpower constructed to enable relivening of the New Brighton Substation after it was sunk by liquefaction from the M6.3 aftershock of the 22nd February 2011.

The extension runs to a new substation in Rawhiti Domain in New Brighton, which did not (and in future, hopefully won't) get much liquefaction. See 'Analysis' for further information.

New Brighton substation - a door even I can reach!
Work log: 

Monday 30th May: Install 66kV poles on Keyes Road.

Tuesday 31 May: Start running 66kV conductors, Baker St.

Wednesday 1 June: Run 66kV conductors from Baker St to Keyes Rd.

Thursday 2 June: JOINTING: Prebbleton substation installation.

Prebbleton substation

11 and 33kV cables underneath the Prebbleton substation

Friday 3 June: Run 66kV conductors into Rawhiti substation.

ANALYSIS: How to relocate a substation and its circuits

Footage of the quake itself

Footage of liquefaction

The 22 Feb aftershock damaged Christchurch city power (and general) infrastructure terribly. As shown earlier in this blog, not only were subterranean power cables damaged and torn apart, substations were damaged also, and some sunk. The most crucial substation was the New Brighton substation on Pages Road.

The sunken New Brighton substation
Orion, Christchurch's power distribution company, immediately swung into action to get the power back on in  the Eastern suburbs due to cable failures and the afore-mentioned substation. The underground 66kV oil-filled  cable that originally supplied New Brighton substation was broken, bent and sheared off in many locations, rendering it unrepairable.

Uppermost embedded in the concrete is a damaged section of the original 66kV oil-filled cable that supplied New Brighton  substation. Fully exposed is a damaged 11kV PILCA cable.

Orion called on some of its contractors, Connetics and Mainpower in conjunction with Transpower's contractor, Transfield, to construct an overhead 66kV circuit from the Transpower Bromley substation (which itself received damage) to the sunken New Brighton substation. This line was constructed in two weeks. In a normal situation, it would take around 18 months to get resource consent and approval to construct this kind of circuit.

Circuit map of the 66kV installed in record time inside 2 weeks after Feb 22nd.

Whilst the circuit was being constructed, the substation itself had to have tonnes of silt removed from inside to allow use of it again, and the two 66kV-11kV transformers had to be replaced by a single undamaged transformer, which I understand was obtained from Ilam substation.

The dark mark shows the level the silt was up to inside the substation.
After several 11kV underground cable faults were repaired, New Brighton substation was able to be re-energized, providing power to much of the Eastern side of Christchurch, including my own house (unfortunately it was too late for the anemones, clams, corals, tubeworms, starfish, and the Mandarin fish in our saltwater tropical fish tank, but hey, we're alive, right?).

The decision was undertaken to move the location of the New Brighton substation to a location that was not so prone to liquefaction and lateral spread, and Rawhiti Domain was deemed to be suitable.

Immediately the decision was made, preparations for construction began at the new substation site. This is another project that is being achieved in record speed.

Work beginning on Rawhiti substation site

A closer look

Good public information. All residents affected were given letterbox drops.
Once the substation was almost ready, Connetics and Independent Line Services were again contracted to do 66kV overhead lines, this time extending the original Bromley-New Brighton circuit to Rawhiti substation.

Circuit map of the New Brighton substation - Rawhiti substation run.
Pole installation began on the 25th May. The Connetics crews I was working with were on the northern side of the Avon river, Independent Lines Services doing the southern side and the river crossing.

Unfortunately I contracted a Gastronomic Virus at the start, so I was unable to see the first poles installed down Baker Street. I did, however, take a series of photos showing before, during and after..

A common misconception expressed by the public I spoke to on many an occasion was over the poles 'not all being straight'. Several poles are 'strainers', which means they are set at an angle on purpose on the outside of a bend or turn. 'Breast blocks' and 'Heel blocks' are pieces of pole underground which are actually used to keep the pole set at the angle it's set at.

Diagram of how underground blocks work.

Baker St poles

Live lines being temporarily held aloft while the existing pole is replaced with a much bigger 66kV one.

Live lines being temporarily held aloft while the existing pole is replaced with a much bigger 66kV one.
The insulated temporary crossarm, with spring loaded 'rat traps' which can be released using insulated 'hot sticks'.

Reconnecting LV crossarm and insulators

The 66kV HV line being strung above the LV crossarm

The poles were all installed, and the conductors done by 'streets', Baker St the first day, Gresham St the second day, and Keyes Rd into the substation on the third day.

As with Dallington, insulators were placed on the LV circuits below where we were running the 66kV conductors, and the conductors were fed through rollers attached to the insulators.

All rollers in place

Blair feeding conductor through a roller

Tim showing his pulling power!

Me being creative.. a view from the cable drum rollers. Winches are holding the conductors from rolling out and contacting the ground.

'Pistol grips' were used at every 90 degree pole, which is the norm. This allows the conductor to be run 'street by street'.

A 90-degree turn pole.

The substation wasn't quite ready for us, but conductors were run into place on time into the substation for connection onto onsite insulators.

Substation technicians install equipment

The transformer cooling unit arriving

Transformer and cooling unit in place. The overhead cables connect from the left of this picture.

The final run. 
Once again, I am left in awe of the commitment of the supply industry workers, flawless, methodical work being done with all safety procedures being observed to the letter. Once again I observed the Line Mechanic 'psychic' ability of knowing the procedure inside out and working as one with little communication. Observation linked to good training and a professional attitude seem to be the keys to this ability.

The three 66kV overhead circuits that have been constructed to help keep the power  on in Christchurch due to the M6.3 quake 22 February.

Next week I will cover connecting up 4x 1 Megawatt generators at QEII for bolstering the Eastern network over the winter. As seen on Queens' Birthday Monday, our shaking hasn't stopped and keeping the power network going over this winter is going to be a real task for Orion and its industry partners.

A sign that was attached to one of the new 66kV poles on Baker St. you just can't please everybody!


selena said...

Hi Andrew,

trust all Ok after yesterday's 5.5 and 6.0. CPIT closed today and hopefully be back to 'normal' on Wednesday.

No doubt this latest event has undone some of the work you have been involved with :( and you will need to revisit work already completed.

Keep up the good work. This post does a really good explanation of the process of getting electrical supply up and running again - no mean feat - my gratitute to everyone for keeping things running.

Keep up the blogging and let's meet before the semester ends for you to consolidate your material to complete DTLT 604.

All the best for a another busy week, Selena

Andrew said...

Hi Selena!

YES, we're busy! But it seems that it's not as bad as February, but similar to September.
I'm back at CPIT on 4th July. Is that early enough to meet?

Hope you're well and safe!

Andrew ;D