Ps 135:7 "The Lord Jesus causes the vapours to ascend from the ends of the earth, He makes lightning for the rain, He brings the wind out of His treasuries"

Twitter   LinkedIn   Flickr
Company History

Live Line Technology lightning protection products were developed in the mid 1980s out of the dire need in the South African electrical utility industry for an answer to excessive over voltage related damage to distribution networks. Despite utilising conventional surge protection, an unprecedented amount of equipment was being lost due to over voltage occurrences.

High rates of surge arrestor failures & lack of surge arrestor maintenance were largely responsible for millions of rands of losses to overhead equipment, especially during the rainy seasons. Other inherent problems to overhead networks was the incorrect surge arrestor configuration at pole-mounted & power transformers 

New surge arrestor technology development involved the following steps :

  1. Identification of the need.
  2. Research & development.
  3. Implementation of the new technology.
Identification of needs  Surge arrestor failures:

  1. Distribution surge arrestors, took field staff lengthy periods of time to change when they were spent. This often resulted in the units not being maintained (replaced), thus damage to the overhead equipment then followed.
  2. The blown surge arrestor ground leads were not always properly identified when they were spent. Over-burdened service officials were often reluctant in their maintenance schedules , as other more critical work, always got priority. Damage to transformers & other overhead equipment followed these situations.
  3. The surge arrestors earth lead were not always blowing clear off lines, causing S.E.Fs (Sensitive Earth Faults).
  4. GLDs (Grounding Line Disconnectors) were incorrectly graded for the South African market. The GLDs were being manufactured internationally and were either too sensitive or insensitive, and created nuisance surge arrestor failures or the opposite, which meant faulty surge arrestors were not being cleared by the G.L.D
  5. Occasionally Staff were killed or injured doing maintenance changing Arrestors on lines.

Research & Development Phase :

During thunder and lightning storms, faults within electrical utilities are ubiquitous. Fault identification , isolation and rectification reach stressful levels as the number of faults, are often too much to handle for the dedicated number of electrical technicians. Nuisance fuse blows on 11Kv and 22Kv pole-mounted transformers were the areas of concern in these models.

1  Reactive maintenance

The process of new technology integration began when Live Line Technology researched and developed an overhead phase indicator to identify single phasing quicker and more effectively at the pole-mounted transformer. The indicator was developed to provide an easy visual indication of a downed phase, by using the corona effect of each working phase.. It was measured and did reduce fault identification time, but didnt do much to make the rectification of the fault easier. Thus the idea was to provide a more ] effective maintenance model, for the components at the pole mounted transformers which were causing most of the faults.

According to the 4 levels of maintenance, this was only a short term effort.

Fig B1. The overhead phase indicator was a reactive approach to rectification of faults. The unit was placed on all three phases at the pole mounted transformer, to provide quicker :

- Identification of the fault - Isolation of the fault. - Rectification of the fault.

A black box worked inconjunction with the phase indicator and was placed in the customers home. This also provided a visual indication as to which one of the phases had gone down. The objective was to achieve quicker identification, isolation and rectification of the fault. This was still not the ideal, but a good starting point in the right direction, to improving surge arrestor maintenance on distribution lines.

Fig B2. The Black box was a cost effective method of single phasing identification for rural customers. The identification of a downed phase, was identified by a red LED no longer shining. It was no bigger than a lighter and assisted fault finding,

- Identification of the fault - Isolation of the fault. - Rectification of the fault.

2 - Preventative maintenance

A more concerted effort was needed to ensure that field staff wouldnt only properly identify the spent surge arrestor but would also be more co-operative in the replacement of these units.

Live Line Technology thus designed a surge arrestor that could be maintained live line without the need of an outage. After the first year of implementation, the results were measured against return on assets and initial investment. The return on investment was realized in the first season of their implementation and equipment was saved from over voltage occurrences.

MOV (Metal oxide) surge arrestors of today have come a far way from their GAP type predecessors. The MOVs protective margins are 10%-15% higher than the gap type, their insulation from moisture is superior and their GLD (ground lead disconnectors are specifically graded to disconnect at the correct amperage curves.

However, when it comes to the end of its lifetime (being several months or years) maintenance of these units requires , an outage. This means an outage needs to be performed and the customer needs to be informed by the utility to ensure that, the unit is replaced

3  Predictive maintenance

The next level in the upgrading of a electrical utilities system is predictive maintenance.

To be able to forecast when a fault is going to occur, and to be proactive in the approach of the problem. Further analysis of DDT-1860, (the pole-mounted transformer configuration of fuse cut-outs and surge arrestors) revealed that excessive fuse blows were causing nuisance faults during thunderstorms. Thus by analysing and changing the existing configuration, a different set of cause-effect was affected.

When the properties and purpose of both the fuse and surge arrestor were compared the results were glaring.

Fuse properties
Low current dissipation capabilities.
Rated from 1A- 100A
Isolate over current faults.
Cannot be rated for lightning.
versus Surge Arrestor properties
High current dissipation capabilities
Standard ratings start at 10Ka
Discharge excess voltages
Designed for lightning protection.

4  Prevention maintenance The ultimate level in any electrical network is the prevention maintenance model.

Surge arrestors are vital over voltage safety protection devices which need to be placed close to all overhead equipment. More importantly once a line is populated with these units, they need to be maintained healthy. Unfortunately most surge arrestors do not have a formal warning system to warn the utlity once a surge arrestor has been spent.

Technology dependant warning systems are not available in the surge arrestor product market, and this leaves overhead equipment vulnerable to over voltage occurrences. The Transformer losses within South Africa were up to three times higher than the average electrical utility adding up to hundreds of millions of rands lost.

The Transformer combi unit, placed at pole mounted transformers was designed to provide an arrestor alert warning system and ensure 100% over voltage protection at all times. Once this technology was implemented and installed, provided a 90% savings in the first season, where transformers were once lost to over voltage damage.

Implementation of the new technology :

Transformer combi unit features :

The Transformer Combi Unit protects distribution transformers against lightning & surges. It holds both the fuse carrier & live line arrestor in a parallel configuration which is the most scientifically accepted configuration for dealing with over voltage & transients.

Unique Arrestor alert.

The surge arrestor is critical to the operation of the Transformer Combi unit. Once the surge arrestor is spent, it alerts the operator by dropping out. The Transformer Combi Unit, has a facility on its pole clamp, for the spare arrestor which then can be replaced on the spot.

Replace the Fuse carrier & Arrestor with a Link Stick.

Electrical Utilities experience no more transformer losses and a reduction in outages. The maintenance procedure for or surge arrestors is made more effective.

Elimination of outages

The Customer experiences a much better quality of supply, due to the surge arrestors enhanced protection capabilities, protecting both the transformer and fuse.

Reduction in single phasing

A 90% reduction in single phasing due to the fact that the fuse remains healthy during lightning storms.

Practical Installation

Contact sales at :
Int: (0027) 468 3344
Tel: (018) 468 3344
Fax: (018) 468 3303

<< Back to Homepage