The renovation and modernisation of equipment makes it possible to manage the obsolescence of existing equipment and to ensure the durability of installations without having to replace the entire LV switchboard.
It is therefore possible to maintain the characteristics of the original equipment and functional unit or even increase its capacity while ensuring continuity of service, performance and safety.

In the case study below, our Comeca Services teams have carried out the modernisation of all 303 drawers and 34 incomers installed in the existing NORMABLOC switchboards at one of our customers, a major player in the nuclear sector.

How to modernise Normabloc LV switchboards which have become obsolete in the nuclear environment?

We regularly intervene and manufacture replacement drawers and retrofits for this customer. Our support is complete, as we also carry out level IV manufacturer maintenance for its LV switchboards.

The installation consists of 13 low-voltage switchboards including 11 NORMABLOC N660 (rear connection) and N680 (front connection) switchboards. These Low Voltage switchboards, installed in the 1980s, are ageing and some of their equipment has become obsolete. This is the case of the existing UNELEC type circuit breakers which are no longer marketed as well as the Evocom relays manufactured by Comeca.

The renovation of NORMABLOC switchboards under nuclear constraints

Although the structure of the switchboard is in good condition, all the outgoing and incoming feeders must be replaced in view of the obsolete material detected. On the other hand, our teams must meet a major constraint: the outgoing and incoming feeders must be put back into service at the end of the day in order to avoid a production stoppage. Indeed, stoppage is unthinkable in such a demanding environment as the energy production sector.

To overcome the obsolescence of the equipment, two solutions are possible:

• Complete replacement of LV switchboards
• Renovation

Why choose renovation in this particular case?

The option of replacing all the switchboards implies a production stoppage and a high acquisition cost. In addition, the intervention on a nuclear reprocessing site requires the switchboard to be stopped for less than a day. The replacement of complete switchboards is therefore impossible since this type of intervention can last several days.

The solution chosen was therefore to renovate its equipment (drawers and incomings) in order to keep the existing equipment functional for several years, while limiting the production stoppage to a strict minimum during the intervention.

Once the technical solution has been designed and approved in collaboration with the client and our technical teams, we help our client to calculate the cost of the equipment to be replaced for the entire project by providing innovative technical solutions.

Comeca offers specific solutions for demanding environments

Due to the operating constraints of this nuclear site, the LVBs must be put back into service each evening to ensure continuity of service. In response to this problem, our teams offer a solution for effectively going back in time in the event of unfinished work in the evening before the technicians leave.

This solution makes it possible to plug in the old drawers again to supply the existing loads if the intervention could not be completed before the end of the day. For example, if the equipment is unavailable or an alarm is triggered on site.

Our response COMECA Services: performance and safety

In 2016, a pilot project was carried out on each type of equipment with the aim of validating the technical solution and rolling it out to a set of switchboards. This project is the result of 4 years of work in collaboration with our client. Here are the various works and replacements that we carries out to modernise all 303 drawers and 34 incomers of the NORMABLOC switchboards.

• Modernisation of communications with the replacement of EVOCOM cards with 79 FDM128 measurement units.

Thanks to a PLC and a communication network, the information is sent to a central measuring unit. The control units are placed on the outgoing and incoming columns.

• Retrofitting the incoming feeders in the columns: Retrofitting consists of replacing obsolete open circuit breakers (no longer on the market or unavailability of spare parts) with new generation circuit breakers of the communicating type via FDM measurement units in our case.

Each incoming feeder, whether normal or emergency, is equipped with data loggers (FDM128) to monitor the status of the circuit breakers (switching on or off) and the feedback of information (energy consumption) to a supervision screen.

• Retrofitting of the new generation feeders in the outgoing columns: all drawers were replaced by new generation drawers (remote monitoring).

These communicating drawers can be used for both supervision and prevention of ageing of the elements supplied by the switchboard. It provides information on the switching on or off of the circuit breaker...

Would you like to know more about our retrofit solutions?

• The addition of 12 lightning protection drawers (1 lightning drawer per incoming feeder): They protect the electrical panel against transient overvoltages linked to a lightning strike by evacuating the energy towards the earth. Lightning can impact the entire electrical installation of the main switchboard and cause short-circuit risks, and generate faults on the electronic cards for example.

Lightning Surge Arrestor

These Surge Arrestor Compartments are removable and interchangeable: if a lightning strike damages the drawer, it can be changed safely and without disconnecting the LV switchboard and then put back in place without danger. On the front of this drawer there is an "in service" light indicating the presence of voltage on the drawer.

• LV switchboards Manufacturer maintenance of level IV:

When the LV switchboards are shut down, the busbars are accessible and can be checked. During the maintenance operation we mainly check:

If a defect is found, the copper bars and bolts must be replaced.

In summary

The COMECA teams are accompanying and advising this major nuclear player throughout this large-scale project. Our skills and expertise enable us to offer modern solutions accompanied by communication systems to facilitate maintenance and remote monitoring of the panels.

The specificities of demanding environments require our engineering teams to focus on the safety and adaptability of the proposed solutions. Our objective: to support you throughout the life of your equipment while guaranteeing the best investment / service continuity ratio.