Monday, November 12, 2012

November 2012 - Still moving forward...

The earthquake recovery for the Christchurch distribution network is moving forward with the 'pull' of eighteen 900 metre lengths of 66,000 volt cable to link McFaddens zone substation to Dallington substation. The complete run is 5km long, but due to the fact the cables will separately conduct all three phases, then 18x 900m lengths is what is needed. This is the first stage of a programme that will effectively give Christchurch a 66,000 volt 'ring circuit', which enables 'backfeeding' should one section of the circuit fail.

The McFaddens - Dallington underground 66kV circuit. Red circles are cable joints.

The cables will be laid by contractor Cable Layers, and are scheduled to commence the first stage around the 5th of December. I will cover this in my next post. 

This is the first stage in a plan by Orion to consolidate the 66kV underground Christchurch distribution network and provide an even more reliable supply of electricity to the earthquake-damaged eastern suburbs of Christchurch.

Some sections of the cable will be laid on top of steel-reinforced concrete, which will protect the cable if yet another substantial earthquake occurs, an example of 66kV oil-filled cable damage is shown in my earlier post here on the 17th March 2011.

The end for New Brighton substation

The New Brighton substation, which sank due to severe liquefaction in the February 22nd and June 13th earthquakes is finally being demolished.

The New Brighton substation before the quakes (google streetview)

The sunken transformer building in ejecta from the process of liquefaction

Ejecta (silt) around the back of 11kV circuit breakers in the New Brighton substation

The New Brighton substation being demolished

66kV cables that fed the substation were irreparably damaged in the quake, and a temporary transformer was quickly sourced from (Ilam?) substation to supplement the two transformers in their transformer buildings. 

The New Brighton substation. Temporary transformer on far left of picture.

A temporary 66kV pole circuit was designed by Roger Sutton and his team (then CEO of Orion) using a marker pen on a printed Google Maps map, which was approved by the emergency Civil Defence controller, who was in charge at the time due to a national state of emergency being in effect. A three-year grace was given, after which time, the normal consent process to retain the poles would have to be observed.

Map of the pole circuits installed after 22nd February 2011

Contracting firms built the 5km long pole circuit in an incredible 2 weeks, effectively shortcutting the normal process to construct such a circuit by at least 18 months, and succeeded in getting a large amount of quake-affected customers' power back on. Unfortunately it took much longer to get all the power back on, as would be expected from a disaster of that magnitude.

Rapid work then began on building a new zone substation at Rawhiti Domain, an area not affected by liquefaction to replace New Brighton substation.  The 66kV temporary circuit from Grid Exit Point (GXP) Bromley was extended to Rawhiti in June 2011. Rawhiti substation was opened on the 14th February 2012.

The new Rawhiti substation

Eventually both the 66kV pole circuits installed rapidly after the Feburary 22nd 2011 earthquake will be replaced with new underground cables, completing the 'ring circuit'.

So ends an era for New Brighton substation. It supplied Christchurch's eastern suburbs for many good years, yet another victim of the February 22nd 2011 earthquake.