Tuesday, May 17, 2011

Weeks 14 & 15 - Subs department - Brookside, Hororata, Greendale Substations, Test Room

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 reconnect 11kV supply cable, Cannon Hill Crescent.

Australian cable jointers helping fix our broken network

Uppermost cable is earthquake damaged steel and lead armoured 11kV  HDPE cable. Lower is replacement XLPE.

Damaged 11kV PILCA cable marked pink for jointers
Friday: 6 May: Sheath test 66kV cable between Papanui and McFaddens Rd Substations. Find fault on Orchard Rd and Bridge St lighting circuits.

McFaddens Rd Substation 66kV transformer building

Nigel from the Test Room earthing a 66kV circuit prior to the sheath test
Monday 9th May: Red Zone 66kV sheath test and Bankside LV underground cable fault.

Inside the Red Zone near Victoria Square.. Which building is 'wrong'?

The same jointers (Shaun Baker and Barry Kelly) that got Dallington Substation reconnected repair the Addington-Armagh 66kV Oil-filled cable

The Armagh "inside" substation

Robbie and Steve dig for a low-voltage (LV) cable after the fault has been found with the 'thumper'.

Nigel replaces pole fuses 

Tuesday 10th May: Find faulty 11kV cable between Beach Road substation and New Brighton substation using TDR and 'thumper'.

Connetics and Delta (Otago) vehicles at Beach Rd sub

The TDR (time domain reflectometer) in action

Peter from Delta using listening equipment for 'thumping'

Marking the faulty cable after 'thumping'

Wednesday 11th May: Red Zone test 11kV cable.

The CTV elevator shaft and stairwell is demolished.
A Madras St sub. Left is the gap where a church was.

Thursday 12th May: Ferry Road LV cable fault find and repair.

LV fault found using 'thumper'

Existing joint torn apart by earthquake.

Friday 13th May: Isolate/Test/Join/Test/Energize 11kV XLPE cable Shands Road.

Analysis: Subs and Test room departments

Subs are electrical fitters, which is the supply equivalent of industrial electricians, of which I am one. The work the subs workers do is very familiar to me and I felt quite at home in their workshop and on-job with them. However, the point of my ASL is not to be in my 'comfort zone', and to throw myself at the unfamiliar and learn it, so educationwise, it was, however, not hugely beneficial for me to spend too much time in subs, so I limited that to just three days.

The Test Room, however, is a whole new ballgame for me. The workers in the test room are the network 'fault finders', 'isolators', 'energizers', and almost direct the repair of the network. Faults in underground and overhead cables are found using complex pieces of equipment acting upon order sheets from network owner Orion.
There are two ways the Test Room operate; faults and scheduled maintenance.

Faults are identified by the network controller in the control room or rung in by the public. Orion will then use a Network Operator to identify the fault or faulty circuit. Often the supply to consumers can be maintained by 'ring circuits' or 'backfeeding'.
Once the faulty circuit is identified, the Operator will disconnect the circuit by operating circuit breakers or removing fuses or links.

The Orion 'Operating order' sheet

The job is then passed on to the Test Room for fault diagnosis and identification. The faulty cable is tested, and once the fault location identified, the cable is earthed.
This is where the picture becomes complete. A 'dig up' crew carefully exposes the faulty cable, cable jointers 'spike' the cable, and then repair the cable. The Test Room then test the cable once the jointers are clear, and if the cable is found to be without fault, the circuit is possibly re-energized, if Orion require it to be.

'Scheduled maintenance' is very similar, except a fault does not need to be found. Usually it involves a cable movement or connection change, once again involving the Cable Jointers.

My time in the Test Room completes a cycle of learning for me, I now have full understanding of the process involved in repairing a damaged cable. It would not be appropriate for me to endeavour into the very flash toys the Test Room employ to fault find cables with, as my focus at Connetics really is Cable Jointing and Line Mechanic work.

Analysis: Line Mechanic Vehicles

Line Mechanics have a large scope of work to cover; wooden poles, metal poles, reinforced concrete poles, and towers (pylons) must all be worked upon. A Line Mechanics' truck must be fully equipped for any eventuality as they sometimes work very far afield. There are two trucks used:

'HIAB' Truck

The 'HIAB' or 'crane' truck
The 'HIAB' truck is so named from one of the first models of transportable hydraulic crane trucks; Hydrauliska Industri AB, which is a Finnish manufacturer of loader cranes, demountable container handlers, forestry cranes, truck-mounted forklifts and tail lifts. See HERE.

The HIAB truck is predominantly used for pole handling and live line work. It's powerful yet compact when packed away crane is ideal for Line Mechanics' use. With plenty of cargo space on the back, and room for compartments in the side, it is a fully mobile workshop and crane. 

A skilled crane operator can make a job far, far easier and less time consuming than a less experienced operator. Dual controls, one set either side of the rear of the truck enable ease of operation.

In addition to the hydraulic crane, there are hydraulic stability legs to prevent the truck capsizing under crane loads. 

Another clever addition the HIAB truck has is a fully insulated 'line holder'. This device holds conductors up in the air when doing live line jobs as a temporary 'pole'. 

The 'line holder'
The HIAB being the 'pole'
Tool and equipment compartments

Spare part compartments and even a jug and toastie maker!

Fuel and chainsaw

The deck
There are many other uses for a HIAB truck, these are just a simple overview.

'Bucket Truck' or 'Cherry Picker'

The 'Bucket truck' or 'cherry picker'

The 'bucket truck' is a vehicle primarily used for line mechanic access to poles and overhead network systems. It has a hydraulic telescoping arm, the last section being made of an insulating material for safety.

The bucket can legally be used as a work platform and line mechanics must wear harnesses (as when up poles as well) and be anchored inside the bucket as part of safe operating procedure. Dual controls, one set inside the bucket and one set on the truck deck allow for easy operation. Stability legs are also used on the bucket truck. Connetics bucket truck buckets are rated at 200kg total weight.

The 'bucket truck' tool compartments

'Going hard' on the 66kV Bromley-Dallington install in the buckets

Safety harness
It's a long way up; this is not a job for people with a fear of heights!

Between the two vehicles, the Line Mechanic must be competent in:

  • Driving a HT (Heavy trade) vehicle (licence required)
  • Operating a HIAB hydraulic crane (licence required)
  • Operating a bucket truck (licence required)
  • 'Hot stick' or 'Glove and barrier' rating if working on live lines

I realise that my ASL, which was initially to gain experience in the supply industry in Cable Jointing and Line Mechanic work, has grown to actually being a recording of history. My Picasa account will have all my earthquake related photos. I'm more than happy to make them public. Institutions must make reference to CPIT if you choose to use them please.

I would like to extend a greeting to ETITO viewers, too, from the newsletter. Feel free to ask questions!

From Bedford Row, where I was when the M6.3 quake hit, with the Hotel Grand Chancellor leaning ominously behind.


selena said...

Hi Andrew,

could not get on to your blog last week as I was in China and they block blogger!!

Good to catch up this week and see you have recorded your learning.
Just one item to clarify, I sort of know what a 'thumper' does, but what actually is it? and how does it work :)

Keep up the blogging, Selena

Andrew said...

Hi Selena, welcome back!

Ahh... Ok! A 'thumper' is a piece of equipment that finds faulty underground cables. The way it works is by using the fault itself as an indicator.

When an underground cable faults, a live conductor comes into low(ish) resistance contact with either the earth potential conductor or the earth itself.

A 'thumper' discharges a large amount of electrical energy at once (a bit like a camera flash) through the fault. The resulting arc creates an underground explosion, which can be heard with special listening equipment or audibly, depending on the amount of ambient noise. Sometimes it jolts the ground underfoot!

Hope this helps your understanding!