November 24, 2017

Meticulous planning, right installation and consistent inspection

DEHN Africa advises mines in Africa to be well-resourced to manage the increasing risks of lightning flashes and surges to their operations.

When lightning flashes occur in mines, in most cases, the consequences can be catastrophic, with fatalities recorded and untold damage to equipment running into hundreds of millions of dollars. The greatest concern is whether mines are well-equipped enough to mitigate the potential events. Various pieces of legislation, mainly the Mine Health and Safety Act (MHSA) and Occupational Health and Safety (OHS) Act, which emphasise safety of workers in mines, render lightning and surge protection compulsory, yet it isn’t readily considered and implemented.

DEHN Africa fears that many mines in South Africa and other countries on the continent might be more vulnerable to lightning flashes events than they think. For this reason, it is imparting advice to mines on implementing a sound approach to surge and lightning protection in their operations.

DEHN Africa is the local subsidiary of Germany-based lightning and surge protection, earthing components and safety equipment manufacturer, DEHN + SÖHNE. DEHN specialises in earthing and lightning protection solutions in various market sectors. This includes areas such as building technology, transportation, telecommunication, process automation and the energy sector (photovoltaic systems, wind turbines, renewables and so on).

In an interview with African Mining Brief, the Managing Director of DEHN Africa, Hannes Ackermann, says he believes that most mines in South Africa and other countries on the continent might be more vulnerable to lightning flashes than they think. “Most mining companies may think that the chances of damage from lightning discharges are remote, but they do not imagine that they could be facing the next event. DEHN believes that prevention and mitigation is better than cure,” he comments.

Common oversights 

While working with mines, DEHN Africa has noticed a number of oversights which increase the vulnerability of mines to lightning flash damage. These are mainly a relaxed attitude, thinking that ‘one lightning protection system (LPS) design fits all’, poor installation practices and lack of inspections, overlooking protection for  sensitive and critical  electronic equipment, non-compliant products of poor quality / design and a lack of knowledge with respect to external lightning protection (ELP) design.

Looking at each point in more detail, Ackermann notes the following:

  1. Proactive rather than reactive approach

There is a tendency to be reactive rather than proactive about LPSes belatedly, after fatalities and damage to valuable equipment have occurred.

  1. One LPS design does not fit all

There is an erroneous assumption that the design of earthing protection systems and an LPS that has worked in a specific scenario in one mine can be just as effective in another. This flawed approach is in itself a risk, cautions Ackermann.  Instead, for a more effective LPS design when it comes to a particular mine, a prior risk assessment according to SANS IEC 62305 is obligatory.

  • Overlooking sensitive electronic equipment

Another oversight, Ackermann points out, is that mines focus on external lightning protection and earthing and overlook the vulnerability of their sensitive electronic equipment. “Some mining companies neglect to consider surge protection on their sensitive electronics and electrical equipment. Surge arresters fitted on the high voltage (HV) lines cannot offer the required protection to low voltage (LV) equipment,” he explains.

Ackermann adds: “As more technology-sensitive mechanisation, automation and communications equipment is deployed in mines, the level of lightning-related damage and safety risks which mines face is escalated. Electronic equipment in a mine is not safe, unless adequately protected, contrary to what some believe.”

  1. Poor installation practices and inferior products

Owing to fluctuating commodity prices, mining companies are being tempted to opt for ‘affordable’ means in their procurement processes in order to cut costs. Ackermann says that when we consider earthing and lightning protection, the practice of hiring installers who are ‘jacks of all trades and masters of none’, instead of organisations with a proven track record, backfires.

“First of all, installers who are not qualified do not follow the correct standards and procedures of installation. In particular, this has been observed with high voltage resistant insulated cable installations and other earthing and lightning installations in general. It is a problem of “not knowing better” versus blatantly cutting costs in workmanship, using noncompliant products and trying to squeeze the most profit from the project. This will have consequences.”

  1. Irregular (or lack of) inspection and testing

An LPS needs to be regularly inspected, as corrosion, maintenance and installation due to wear and tear may lead to the LPS becoming ineffective. As much as correct design and proper component selection and installation is required, regular inspection and testing will provide the assurance that the equipment is properly protected and the risks mitigated, as far as possible.

Fatalities and damage to equipment

The damages to equipment could have a massive impact on mining operations. Downtime to equipment leads to production losses, loss of revenue and loss of income, which is sometimes worse than actual damage to equipment. Consequential losses are far worse than actual losses.

Two incidents that occurred in South Africa a few years back illustrate the magnitude of the impact of lightning flashes. After lightning had caused the failure of a primary water pumping system, underground flooding closed a mine for 45 days. In another incident, after a lightning flash had disabled two substations near an underground mine, mineworkers were trapped two kilometres below the surface, and as result production was suspended.

Effective lightning protection

An LPS should be effectively planned, installed and maintained by experienced professionals, and Ackermann singles out three main steps, as follows: engagement and design with an expert LPS solutions provider who provides a detailed report identifying risks and a mitigation strategy; correct component selection and accredited installations; and regular inspections and compliance verification.

  • Engagement and design including risk assessment

Before implementing an LPS, a detailed engagement and design needs to be conducted, with a risk assessment being essential. Findings from the assessment provide the correct risk mitigation strategy for a particular site or sites. A risk analysis should be conducted in accordance with South African National Standards (SANS) IEC 62305 specifications.

On the significance of risk assessment, Ackermann says: “It is important to identify structures and critical equipment which could be damaged, and carry out soil testing and other necessary investigative procedures. The effects of downtime, as well as damage to property and other factors are considered, and the risk are analysed. Based on the site assessment data, the actual results from earth resistance tests and so on, a strategy to mitigate the consequences can be developed and implemented according to the risk management tooling provided by DEHN.

  • Correct component selection and accredited installers

For safety issues like lightning protection, cutting corners to save money can expose mines to costly damage and fatalities to employees. And so, it is advisable to choose the correct products based on the required KA ratings, latest design standards and guidelines and also to use qualified personnel at all times, advises Ackermann.  “The use of qualified and accredited installers is recommended, because this ensures the application of standards through proper installation techniques and guidelines, and according to the industry standards. Accredited installers from  the Earthing and Lightning Protection Association (ELPA) are trained in accordance to these specifications and regulations, tested and certified.

In addition, he says, suppliers have an obligation to train companies that install their equipment and products, to maintain high standards of quality and maintain the brand values. Particular training needed includes product selection and application training, solutions and installation training for specialised solution like HVI High Voltage Insulation solutions.

Urgent action to cope

Given the abovementioned scenario, calls for mines to be adequately prepared to mitigate the consequences of lightning flashes are not alarmist. With global warming resulting in erratic weather patterns globally, there has been increase in thunderstorms. Consequently, there is bound to be an increase in the number of ground flash density on mine sites in the coming years.

Besides, while data for lightning density in towns and cities is readily available from the South African Weather Services (SAWS), it has been established that in remote areas, where most mines are located, lightning ground flash density can be five times higher than the norm.

So, bearing in mind the risks they face, the importance of mines being well-resourced to cope with lightning can simply not be over-emphasised.

Related posts

Leave a Reply

Your email address will not be published. Required fields are marked *

Time limit is exhausted. Please reload the CAPTCHA.