Application of the Cresatech CuTS® system to tackle the safety and service risks caused by removal/theft of grounding material on substation sites.
The worldwide metal theft epidemic has significant impact in many service environments. This impact on safety and service provision is particularly acute in the Electrical Transmission and Distribution industry. While theft of valuable metals causes inconvenience and financial loss in most environments, we are regularly reminded of the consequential damage, power losses, fires, death and injury to both public and power company employees associated with metal theft from electrical networks.
The attraction of substations for theft is well known; the presence of large quantities of high-value copper used to ground infrastructure, which is seen as an easy, low risk target. While this is often the case, the grounding network is not always so benign, as is too often demonstrated through severe injury or worse. To combat this activity, network operators have deployed many types of security solutions. Such solutions either aim to stop access to site (e.g. fences, locks), detect a perpetrator on site (e.g. movement sensors, cameras) or identify the perpetrator after the event (e.g. DNA dyes, cable etching).
These solutions are applied on substation sites commensurate with the size and criticality of the site, with large core transmission sites often having comprehensive camera and movement sensor systems. Due to their numbers, small distribution sites are often limited to fences and locks to prevent access. All these approaches are complementary and can be effective in their specific purpose, though the more costly technologies can have limited deployment due to cost. Substations are physically complex environments and often provide a challenging environment for the more active of these solutions.While the majority of these solutions serve a specific and useful purpose, they do not detect whether the most regularly recurring event has actually happened: removal of material from the grounding infrastructure. Since this event makes a substation inherently unsafe, detection is imperative. The CuTS® system was developed at the request of electrical network operators that, having researched available technologies, could not find a practical and cost effective solution. The design brief for CuTS® that resulted can be summarised as follows:
- Real time detection and notification of removal of grounding materials
- Practical deployment methodology that does not disrupt service delivery
- Suitable for deployment on old and new sites alike
- Suitable for deployment on small and large substations
- Minimal false alarms
- Does not compromise site grounding grid/safety
- Cost effective asset: both capital cost and lifetime costs
- Difficult to circumvent
Working from this design brief, the CuTS® system was funded by and developed in collaboration with the industry, both in the UK and the USA. The resulting system is now being deployed in both markets.
A typical substation theft usually starts with the easy to remove copper connections between the grounded grid under the substation and the equipment and supporting physical infrastructure above ground. Whether steel or reinforced concrete is used for physical support of bus bars, insulators and other site elements, the tapes or cables to the underground grid provide the grounding connection. Some thefts stop at the removal of much of these easy-to-harvest connections on a site. This renders large parts of the site ungrounded. While these are not expensive to replace, their removal renders the site unsafe.
However, many theft events are more comprehensive and the perpetrators move on to more difficult to reach or more challenging infrastructure, which takes time to steal and can cause significant damage. Thieves are often very knowledgeable and know the areas of danger to avoid. Less informed perpetrators will try to harvest cable right up to insulators that support HV bus-bars, often resulting in severe burns or fatalities. Another trend is that of removal of the grounding grid approximately 18 inches/450mm under the surface. After digging down to the grid, hooks are attached to the grounding, the other end of the cable to a vehicle, and as much of the material is hauled out of the ground as they can manage. While this has varying degrees of success in terms of material removed, it does cause significant damage.
At larger substations where there are more security resources deployed, removal of material presents more of a challenge due to movement sensors and thermal cameras, though the more effective of these systems can only be deployed at large sites due to cost. Again, some perpetrators seem remarkably well informed and manage to harvest areas of the site where detection is less likely. A large transmission site that had a significant number of up-to-date cameras and other security resources had more than 40% of its grounding connections removed over a period of time, prior to detection through chance sighting of the damage by security staff (will take two years to re-instate). While the appropriate layers of security for a site can make the theft more difficult to carry out, organised groups continue to carry out damaging raids.
The resulting safety and damage risk
The primary concern raised by copper grounding theft is safety implications. An unsafe site is a danger to the network operators’ personnel, the public and customers at the power delivery points. There are regular reports of substation grounding theft causing power related damage and sometimes fires at customer sites, not just at the substation.
The grounding infrastructure is designed to manage and dissipate faults, both minor and major, and high energy events such as lightning strikes to both lines and the substation itself. When all exposed metal work and equipment is grounded correctly and the grounding grid in place as designed for that specific substation, touch potentials are at safe levels and fault routes operate correctly and have the capacity to manage extreme events. Grounding design and analysis is a complex science and removal of even a part of the grounding infrastructure can have unexpected results.
Most operators have had multiple theft incidents of varying seriousness. Unfortunately a lot of substation engineers have been injured or worse over the years by walking onto sites that have had grounding removed. While awareness is high now and walk round inspections prior to entry common, the more organised perpetrators are careful to steal where visual detection is unlikely so that the maximum material can be harvested from a site over time. While visual inspection does detect the more obvious theft, monitoring of the grounded infrastructure itself is necessary to reduce the risk further. Whether the equipment whose grounding is compromised is a transformer, an automatic or manual switch or other typical site plant, the risks to personnel are clear.
The safety risk to the perpetrators is a less popular discussion, but a liability risk nonetheless, dependent on the country in which the crime is committed. In most countries it is accepted that the operator should do all it reasonably can to protect the criminals from themselves, though this can be difficult to achieve in reality. A fast response once the issue is detected is a significant step forward. While risk to personnel safety is well understood, there are many examples where theft at the substation has caused unstable or faulty power delivery. In rare circumstances this can be dangerous for customers, due to high voltages and/or currents and the possible fires that result (e.g. domestic appliances). While these occurrences are not common, they are a real risk which requires swift action upon detection of the grounding theft at the substation. When they do occur, these events can be quite widespread and the damage and resulting compensation quite costly.
While the safety of people is primary, the resulting potential for damage to operational equipment on and off site is also of concern. While damage usually does not occur upon removal of grounding from a transformer or switch, a voltage imbalance or other fault can stress equipment and cause a fault immediately or over a period of time. Equally a high energy event such as a lightning strike can cause significant widespread damage if the substation equipment is not grounded.
When assessing the costs of a theft event, often only the cost of the copper and its replacement costs are taken into account. The real and potential safety and damage risks and hence costs are variable, but occasionally far higher. Upon assessment of these safety risks and service related costs, the return on investment on roll out is generally between two to four years.
Utilising the CuTS® system to detect and alert upon substation grounding theft as it happens
The CuTS® system, models ZM and ZS were specifically developed in collaboration with the industry for the task of detecting and alerting to grounding theft activity on small and large substations. The primary purpose of the CuTS® system is to help mitigate the safety and operational risks that result from this activity. While it does provide a real time alarm upon such theft activity, its security function is secondary to its capability of notifying an operator when a sites’ safety has been compromised.
The CuTS® system detects removal of material by monitoring for slight but steady changes in inductance of the site grounding infrastructure. This technique is used for its environmental stability and for its minimal cabling required on the site for installation. Since substations have complex grounding infrastructures, the CuTS® methodology breaks a substation into detection zones. This is required so that the slight inductance changes that occur upon grounding removal do not get diluted beyond detectability through looking at too much infrastructure with one sensor.
Very small substations can be monitored with a CuTS®ZS single zone unit. This comprises a single zone card, identical to a ZM zone card. Usually one, maximum two sense wires are distributed to each zone, depending on the topology of the site, ensuring minimal installation work.In conclusion, the ubiquitous safety and service continuity issues generated by site grounding theft have driven power network operators requirements for a cost effective method of detecting such theft activity as it happens. Any approach considered has to be suitable for wide network deployment at both large and small substation sites, since existing protection systems do not alert to theft unless virtually all grounding from site is removed, which is rarely the case. The aim is to alert as theft events occur, so safety and service risks can be mitigated in the most suitable and effective manner. Occurrences of undetected theft at transmission sites through to pole transformers have been responsible for some of the worst safety scenarios for operators and public alike, and have been the cause some of the most damaging and public service interruption events. The scale and cost of undetected theft has led to the development of the CuTS® Solution.
Cresatech U.S.A. Office: 1 303 221 9033
Cresatech Europe Office: 08452 33 55 77