Examples of Acoustic Inspection Services in action
Northpower's Acoustic Inspection Services have been deployed on over 500,000 structures, more than 40,000 sub-transmission poles and 5,000 transmission towers in Australia, Pacific and New Zealand.
Our Acoustic Inspection Service has found over 10,000 electrical defects in these networks that were previously undetected through traditional inspection methods.
Most of those 10,000+ defects had the potential to adversely impact network performance, reliability, security or safety.
Accuracy
Not only is it more reliable, our Acoustic Inspection Service is also more accurate, finding the precise location of each problem.
It runs at 10 times the speed of traditional methods, checking up to:
- 300 distribution poles/structures per day
- 30 - 50 transmission towers per day (depending on access)
- 2 - 4 substations per day (depending on size and distance)
- 30 ground mounted assets per day (depending on access)
Acoustic Inspection Services can detect potential problems at a very early stage, well before they actually become an issue, allowing companies to optimise their maintenance and replacement schedules.
Galvanic corrosion - resulting in micro-arcing and overheating
Galvanic corrosion occurs when two different metals make contact with one another (e.g. aluminium and copper) and the contact area is exposed to moisture. Micro-arcing causes pitting and erosion of the aluminium material and increases the contact resistance of the electrical connection.
There's an increased risk of overheating of the connection/termination which may result in conductor burn, cracked insulators or cable compound leaks.
Advanced stages of this defect type are detectable with thermal imaging camera equipment and eventually through visual inspection. However, this is usually too late for minimising damage and supply disruption.
Using Northpower's Acoustic Inspection Services early detection is possible, allowing you to implement a truly predictive-based maintenance model.
Defective surge arrester – resulting in hazardous leakage currents
Our Acoustic Inspection Service has detected continuous discharge/leakage on surge arrester equipment, where the integrity of the surge arrester was most likely compromised due to lightning strikes.
Internal damage has resulted in reduced energy capability and reduced rated voltage of surge arrester. This defect was not visible to the naked eye, and couldn't be detected using traditional inspection techniques.
A solid earth fault was a likely consequence which could have led to an increased risk to public safety (step and touch potential). The Acoustic Inspection Service detection averted this.
Increased contact resistance – resulting in overheated cable termination
Our Acoustic Inspection Service identified a cable termination defect, where incorrect installation (omission of a spring washer) had resulted in a high resistance termination and consequent overheating.
Thermal imaging can detect this defect type, but only when it's in advanced stages and when the conductor is under load.
We detected this defect type at very early stages, prior to overheating occurring.
Intermittent binder contact – micro-arcing resulting in conductor erosion
Binder wire (tie wire) used to secure the conductor to the insulator must be in direct contact with the bare conductor to ensure electrical integrity.
Separation and/or any insulation between the conductor and binder wire can result in micro-arcing and conductor erosion. Electrical and mechanical properties of the conductor are ultimately compromised and can lead to unplanned outages (power supply interruption).
This defect type is extremely difficult to identify using visual inspection methods - even when in advanced stages of degradation.
Northpower Acoustic Inspection Services can provide early detection of the micro-arcing generated by defects of this type, allowing for planned remedial action.
Reduced clearance distance – resulting in conductor erosion
Reduced clearance distance can result in leakage current between a conductor (jumper wire) and insulator. Continuous discharge (leakage current) can cause conductor erosion, conductor failure and unplanned network outages. This discharge can also contaminate and damage the insulator surface.
Leakage current from reduced clearance between conductors and insulators is easily detected using Northpower Acoustic Inspection Services.
Reduced leakage distance – cracked insulator causing flashover
A cracked insulator results in reduced leakage distance and can lead to electrical breakdown (flashover) and unplanned network outages.
Reduced leakage distance is able to be detected using Northpower Acoustic Inspection Services.
Conductor clamp defects – resulting in conductor erosion
Our Acoustic Inspection Service is able to identify electrical discharge inside a conductor clamp – a defect which is impossible to detect using traditional inspection techniques. The discharge causes heavy pitting and erosion of the conductor (reduced cross-sectional area). The electrical and mechanical properties of the conductor are compromised and the defect can lead to conductor failure and unplanned outages. The discharge can also cause damage to the clamp.
Reduced leakage distance – cracked insulator causing flashover
A cracked insulator results in reduced leakage distance and can lead to electrical breakdown (flashover) and unplanned network outages.
Reduced leakage distance is able to be detected using our Acoustic Inspection Services – in this case on a transmission tower from a distance of around 35m.
Cable termination boot PD (ground mounted switchgear)
Discharge is occurring between the boots of two cables, as a result of insulation breakdown and an installation issue.
Continuous discharge (PD) can cause further damage to the cable termination boot, which may result in ultimate failure and a flashover event to occur causing unplanned network outages.
Air break switch - cracked insulator
A cracked insulator results in reduced leakage distance and can lead to electrical breakdown (flashover) and unplanned network outages.
Cracked insulators on critical assets such as air-break switches, can often impose a safety risk to the operator, and a potential large SAIDI impact.
Reduced leakage distance is able to be detected using our Acoustic Inspection Services - in this case on a distribution pole from a distance of around 12 metres.
For more information
Find out how Northpower Acoustic Inspection Services can assist you to identify network defects and improve maintenance planning and scheduling.
Contact us