Benefits of a predictive maintenance solution for PROFIBUS networks

21 September 2016

Optimising network performance, through the use of a continuous maintenance system, can offer huge cost and energy savings. It also plays a key role in the success of Industry 4.0, smart factories and smart cities.

Across all industries today there is a drive to increase productivity and efficiency with less expenditures. The focus is on introducing cost savings, such as greater energy efficiency or downtime reduction.

Alongside these demands, control engineers also need to be mindful of the trend towards just-in-time production and smaller, customised batch sizes which has resulted in fewer maintenance opportunities. Instead, companies are seeking preventative maintenance solutions – including systems that give warning of a pending network failure and which also allow for remote access to the facility.

Although growth in PROFIBUS DP/PA is now slowing in favour of PROFINET, there are currently still over 50 million PROFIBUS DP nodes and nine million PROFIBUS PA nodes in use across the globe, according to PI International. Taking into account the exceptionally strong loyalty factor towards PROFIBUS and its specifically designed products, there will be some time before Ethernet networks become ubiquitous on the plant floor and overtake the currently installed PROFIBUS DP/PA networks. 

True impact of downtime
Fieldbus and Industrial Ethernet systems alike, the robustness of PROFIBUS networks are compromised by several factors. Having a good understanding of cable length limitations and other installation rules, during the design phase is paramount to ensure the installation meets all electrical standards in order to maximise uptime. PROFIBUS networks are also prone to failures caused by slow degradation due to the often harsh industrial environments which can disrupt plant productivity. Heat, moisture or vibration can result in failures which can initiate a system shutdown. 

It is important to understand the true impact of plant downtime. It could include lost revenue through non-production; the cost of removing product from the production line to make unscheduled repairs; the cost of lost raw materials or damaged products; the cost of getting a process back online; the cost of energy; and the cost of engineers having to determine the underlying issues that led to the downtime.

Innovative backbone solutions
In this age of tight operational and capital budgets, there is real value in monitoring network operations to predict any potential problems. Ensuring maximum system uptime will offer a rapid return on investment when installing a network diagnostic solution. 

One solution is PROCENTEC ComBricks, a continuous 24/7 industrial network maintenance monitoring system for use in PROFIBUS DP/PA automation systems. PROCENTEC ComBricks unites network components and offers permanent monitoring with industry leading features. It enables users to remotely monitor PROFIBUS installations and gives advance warning of any potential system faults, acting as a virtual maintenance professional.  

The use of PROCENTEC ComBricks makes it possible to collect and store network diagnostic data to identify even intermittent network faults, which are usually the most difficult to diagnose and rectify. Based on a set of personalised criteria, it gives an easy to interpret notification that can then be acted upon before a failure occurs. The system works with an integrated web browser which gives secure access to the units via a web connection. 

In addition to the diagnostic features of the ComBricks module, it also works as a modular repeater platform which allows for strategic segmentation of a network to reduce the impact of an outage or malfunction. This is illustrated in Figure 1 as PROCENTEC’s  Innovative Backbone Solutions: PROCENTEC ComBricks combined with ProfiHub and ProfiSwitch repeaters allow for better maintenance control and overall network performance. For the energy sector ComBricks RS 485 is an intrinsically safe SCOPE repeater for use in potentially explosive atmospheres. It is the only available solution for remotely monitoring intrinsically safe segments over Ethernet. The EX i module has an integrated ProfiTrace and oscilloscope for bus level measurements for segments installed in EX zone 1 and 2. 

A real-life example of improving network performance is a waste to energy company in the Netherlands, which implemented the PROCENTEC ComBricks Fiber Optic Ring module. The choice to combine a redundant ring topology with fibre optics was quickly made, as they needed to cover long distances through EMC-sensitive areas. As an additional bonus, the headstation of the ComBricks indicates whether the quality of the fibre optic signal is still optimal. This solution provided permanent diagnostics and strategic segmentation, leading to increased robustness of the network without any EMC-disturbances throughout the installation.

Uncaptured profit
In many industry sectors when a network system shuts down, restarting production after troubleshooting and repairs is a costly and time-consuming task, which further adds to the issues caused by lost productivity. For example, another PROCENTEC customer – a Belgian steel company – says that if its network goes down and stops production, its biggest restarting cost is energy, because the steel will need to be re-heated using energy-hungry gas and electric ovens. 

Understanding the true costs of downtime, repairs and restarting production, leaves the question of how to determine the return of investment of a diagnostic installation. The amount of time a diagnostic solution can reduce in creating clarity of the situation is extremely valuable. In case of the aforementioned steel company, it was estimated that they had a downtime cost of €1,500 per minute. Any solution which allows for increased efficiency in downtime reduction has a high and immediate return on investment.

“If I make this investment, one prevented downtime pays for the whole system,” was the argument made by the maintenance professional of the steel company. There is a lot of internal ‘profit’ to be made by increasing the margins for the company without spending a ton of money. It is time for management to realise the added value of a lifelong ROI on a diagnostic solution and to move the argument of initial cost to the ROI of investment. After all, how do you define the value of safety on your products?

Staying operational
PROCENTEC ComBricks forms an important element of Industry 4.0 or smart factory projects, helping to ensure 24/7 availability of a healthy plant network to enable the continuous flow of data which is vital to Industry 4.0 success. Often innovation is confused with a completely new industry or technology, while overlooking what can be done with existing market-ready solutions. Those companies who seek solutions with today's technologies will be ready for tomorrow. In the future, smart factories will be all about staying operational. Without an operational infrastructure, the true reality of Industry 4.0 cannot be reached.

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