DMS#6168870 Page 1 of 11

Issue 9 30 Jun 2009

PLANT UPDATE

1. New HV and LV bonding methods Pole top fires on Distribution structures are primarily caused by leakage current across the surface of insulators and into the wood. The continual leakage currents concentrated at a specific point on the wood surface which leads to ignition of the wood resulting in a pole top fire/ burning. Photo 1.1 shows an example of charring and Photo 1.2 shows the result of sustained burning and subsequent pole head failure, ie the pole head has burnt-off.

Photo 1.1 Photo 1.2 Photo 1.3

In an initial endeavour to prevent pole top fires, a method of dispersing the concentration of the leakage currents over a larger area was introduced. The dispersion was achieved using of bonding kits, which had gang nails to dissipate the heat and copper conductor to short out insulator studs and cross-arm bolts. The existing bonding kits are shown in Photos 1.4, 1.9, 1.10 & 1.15. The existing bonding kits are electrically connected, via the copper wires, with automotive type slide on connectors. The problem with the existing bonding kits is the slide on connectors are disconnecting from their attachment points or corroding and thus not shorting out the insulator studs and cross-arms as required. Photo 1.3 shows an example of where the bonding wire has become disconnected on the right hand insulator.

To eliminate the problems with the existing bonding kits the following changes are being made to the bonding kits.

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Issue 9 30 Jun 2009

Existing HV intermediate structure bonding for new construction Existing bonding kit CE7553 (see photo 1.4) that was used for application on intermediate steel cross arms.

Previously the gang nail plate did not have the pole bolts passing through the circular hole (approx 25mm diameter). The gang nail plate was simply nailed to the pole and the electrical connection was made via the copper conductor to the pole bolts.

Photo 1.4 CE7553

New HV intermediate structure bonding for new construction The new bonding method is to fit bolts through the dispersion plate with the bolts being fastened to the steel cross-arm. The bolt is held under constant pressure via the coil spring washer. This arrangement will provide a solid electrical connection between the insulator studs and wooden pole head.

An example of the above bonding method is given in Photos 1.5 and 1.6. The drawing showing the bonding is given in the Distribution Construction Standards Handbook (DCSH) in R2/1.

Photos 1.5 Photos 1.6

Initially we will continue to use the existing dispersion plates as shown in Photo 1.7, as we have a large number already in stock. When the existing dispersion plates have been consumed they will be replaced with dispersion plates that have a central circular hole, as shown on Photo 1.8.

Photo 1.7 CE7541 (Old style) Photo 1.8 CE7541 (New style)

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Issue 9 30 Jun 2009

Existing Running disk angle bonding for new construction The bonding kit as shown in photo 1.10a (CE7551) and Photo 1.10b was used for application at a running disc angle structure.

Photo 1.10a CE7551 Photo 1.10b

New Running disk angle bonding for new and existing construction The existing bonding kit has been replaced with the bonding kit shown in Photo 1.11 (CE7542). The bonding kit assembled as shown in Photo 1.12 and Distribution Construction Standards Handbook drawing (DCSH) R2/3.

Photo 1.11 CE7542 Photo 1.12

Steel wire

Bonding clip

Dispersion plate

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Issue 9 30 Jun 2009

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Continued - New Running disk angle bonding for new and existing construction

Photo 1.13 Photo 1.14

Photos 1.13 and 1.14 show the arrangement of the galvanised wire U bonding clip to the phase insulator eye bolts. The 7/1.6 galvanised wire is passed through the U end of the bonding clip with its 17mm diam hole. On the bonding clip of the top and bottom phases a short section of wire must protrude at one end of each clip. This assembly is then placed directly onto the protruding thread of each eye bolt onto the existing nut and secured in a vertical position with the 16mm lock nut provided.

During the securing process the lower nut of the eye bolt must be held while tightening the outer lock nut. This is an essential action for ensuring the contact is well established. Electrically this does not have to attain a given ohm value.

The stay wire eye bolt is not attached by bonding apparatus. The bonding wire must be kept 100mm away from the stay wire eye bolt.

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Issue 9 30 Jun 2009

Existing Retrofit bonding for existing Intermediate wood cross-arm structures Photo 1.15 shows the bonding kit (CE7550) that was used for application on existing HV intermediate wood cross arm structures. Photo 1.3 shows an existing intermediate wood cross arm structure with bonding kit CE7550 applied.

Photo 1.15 CE7550

New Retrofit bonding for existing wood cross-arm Intermediate structures Photo 1.16 shows the bonding kit that is applied to the metal hardware on existing intermediate wood cross arm structures in the fashion seen in Photo1.17 and the Distribution Construction Standards Handbook drawing R2/5.

Photo 1.16 CE7543. Photo 1.17

The insulator studs of the two outer phases are bonded to the king bolts by means of a 7/1.6 steel wire and bonding clips.

Onto the existing nut of the protruding thread of the upper 16mm king bolt of the cross-arm place two bonding clips with the 17mm diam. holes. Into the U end of each of the bonding clip the 7/1.6mm galv. wire is placed and secured with one of the M16 nuts provided. Install the other 17mm diam. hole bonding clip onto the lower king bolt after the galv. steel wire has been assembled as in Photo 1.18 and secure it with the M16 galv. nut.

Assemble the 7/1.6 galv. wire into the two 25mm diam. hole bonding clips for the outer phases so that the wire is passed through the U end of each bonding clip. Ensure that there is protrusion of the galv. wire at each end on the outer clips while at the centre clip the wire passes through. The length of the assembled wire and clips is the distance of the cross-arm from outer phase to outer phase plus 10mm protrusion. The outer phase clips with the galv. wire inserted is then locked onto the existing studs protruding thread with the M24 nuts provided.

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Photo 1.18 CE7539

Photo 1.18 shows the final connection mode to ensure that a thorough electrical contact is established between the outer phases and the king bolts.

Note that on the existing network there are insulators studs with various diameters and field staff must carry a range of nuts that will fit the old insulator studs.

Photo 1.19 CE7539 Photo 1.20 CE7540

Photo 1.9 and 1.20 show the 17mm and 25mm diameter bonding clips with their stock codes.

New Retrofit bonding for existing Wood Strain structures For retro fit bonding of the hardware on existing wood strain structures the stock code CE7542 (see photo 1.11) is applied. The application assembly is in principle the same as for the running disc angle with the exception that it is applied onto the cross-arm eye bolts and not the pole.

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Issue 9 30 Jun 2009

2. Eye Bolt Galvanising The current welded eye bolts used on strain structures, running disc angles and stays, as shown in Photo 2.1, are being replaced by a forged eye bolts as shown in Photo 2.2. The current supplier is experiencing problems with the turn-around/ processing time taken by the only galvanising spinning plant. To get past these issues the supplier is supplying an alternative designed eye bolt as shown in Photo 2.2. The new forged eyebolt has passed the loading tests and is suitable for strain and stay applications.

Photo 2.1 Photo 2.2

Welded Forged

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Issue 9 30 Jun 2009

3. Spreader Rod and Clip In an endeavour to prevent LV conductor clashing a PVC spreader rod, as shown in Photo 3.1, was introduced many years ago. This rod was attached to the conductor by means of a galvanised stainless steel clip see Photo 3.2. and assembled is as shown in Photo 3.3. Although the spreader has been highly successful in eliminating LV conductor clashing it has unfortunately, in time, been damaging the conductors as shown in Photo 3.4.

Photo 3.1 Photo 3.2

Photo 3.3 Photo 3.4

The contributing factors leading to damage/ failure of the conductors were found to be the high leakage currents due to poor insulating properties of the PVC rod, a corrosive chemical reaction between dissimilar materials (aluminium and stainless steel) and the presence of saline moisture or industrial pollution.

There is an ongoing need to prevent LV conductor clashing, thus an alternative nor reactive spreader has been developed.

The new spreader consists of a Ethylene Vinyl Acetate (EVA) rod and stainless steel clip with plastic inserts. The new spreader is shown assembled in Photo 3.7

The EVA rod, shown in Photo 3.5, was tested in accelerated polluted conditions and performed excellently.

The stainless steel clip (see photo 3.6) was also re-developed and a plastic insert was added to provide a bigger contact area and insulation between the stainless steel clip and the aluminium conductor. The plastic insert will help prevent galvanic action.

The new spreader was also subjected to a five million cycle vibration test and no mechanical wear was evident.

Photo 3.5 Photo 3.6 Photo 3.7

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Issue 9 30 Jun 2009

4. Brass Clip Stock code: CE0300

Photo 4.1 shows an earth rod for uni & mini pillar with both the 210 clamp and brass clip installed.

Photo 4.1

Due to the large number of the brass clips being returned to store and not used, the supplier has been requested to supply future earth rods with the 210 clamps only. The brass clips will be discontinued.

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Issue 9 30 Jun 2009

5. Krone LV Fuses Krone supply the existing LV 400A fuse box as a single 3 phase unit, as shown in Photo 5.1 (GS0111). This unit is susceptible to contamination in heavily polluted areas resulting in shorting out the phases. The unit has shorted out as the base is common and tracks over.

Photo 5.1 GS0111

To eliminate problem single three phase unit being compromised by pollution three separate unit will be used. That is, one unit per phase ganged for simultaneous operation.

The new unit will be rated for 400A, replaces both the existing 400A unit (GS0111) and the 160A (GS0110). The 160A unit has been replaced as it is rarely used. The new model fuse box is shown in Photo 5.3 & 5.4.

.

Photo 5.3 Photo 5.4

The new fuse box model GS0111 uses the following fuses: GF2130 (100A) GF1100 (160A).and GF1101 (315A)

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Issue 9 30 Jun 2009

6. Surge Diverter in Nulec Control Box.

The Nu-lec reclosers and Load break switches are currently protected against voltage surges and spikes by means of a 275V (Uc) 80kA (see Photo 6.1) surge diverter installed in the control box.

Over the last few years Western Power experienced failures of these units and subsequent damaged to the control boxes. Evidence showed that these failures generally occurred in areas where the control box was supplied via bare overhead LV conductors. In some cases dead birds were found on the ground close to the installations which indicate some short circuit activity which could have let to higher voltages across the surge diverter and subsequent failure.

The surge diverter has been upgraded to a 460V (Uc) and 100kA energy level, as shown in Photo 6.2. The frame size has remained the same and thus this unit fits onto the existing mounting plate.

Network Performance has advised they will be developing a program to replace the surge diverters in all Recloser and Load break switch control boxes.

Photo 6.1

Photo 6.2