Strypes works with its energy specialists on various infrastructure projects. One of our projects involves a large rail project in which an enthusiastic team has set to work to bundle all its expertise and produce a good design that both Contractor and Client can work with.

With the team, consisting of Strypes specialists and specialists of the Contractor, a standard approach has been applied. The first steps in the approach lead to a capital balance:

• Analysis and insight into all electrical consumers and bottlenecks;
• Setting up an asset balance sheet including various scenarios.

These steps provide a good insight into when a maximum power is taken in a particular scenario. This is important for the rest of the design as the design choices are based on this. The power balance therefore forms the source for the entire energy design. The team took the time to draw up a sound power balance and to design as many scenarios as possible. This provides a good basis for the rest of the design process.

Perform calculations

Once the power balance has been completed, the calculations are made using a V-model. In this model, the high-voltage calculations (10kV) per scenario are first performed in the simulation programme Vision from Phase to Phase. On the basis of these results, it is determined which components will be used. Examples are the short-circuit resistance of a safety device and the rail system in the main distribution boards.

The next step down in the V-model is to perform the low voltage calculations (400V/690V) based on the results of the high voltage calculations. These calculations are performed in the software program Intelec. An important part of these calculations is the selectivity analysis. This analysis ensures that the correct disconnection per protection is guaranteed when a short circuit or overload occurs. This ensures that any faults are dealt with as close to the source as possible and that other electrical consumers are not switched off unnecessarily.

As a result of the low voltage calculations, a number of calculations have been made in accordance with the most current NEN1010 standard. The team carried out cable calculations, short-circuit calculations and voltage drop calculations. With these calculations, the V-model on the left side was run through completely from top to bottom.

Refining the design

After the low voltage calculations were completed, the team picked up the right side of the V-model. On the right side, the results from the low-voltage calculations were processed again in the high-voltage calculations from the first design calculation, a further refinement. This step is necessary so that all the safety devices are well attuned to each other. With this final step, the team completed the complete energy design.

Specific project challenges

In the project, the team faced a number of specific challenges. The team worked closely together to come up with the right solutions and incorporated them into the design. Some of the challenges on this project:

• Influence of cold air flow causing tunnel fans to reduce more current;
• The use of smart adjustable automats to reduce the cable diameter for long cable lengths;
• No-break system sizing on short-circuit power instead of power consumption;
• Implementation of various scenarios in the high-voltage model to simulate critical situations.

Success factor

The team felt it was important for the client to be aware of the design. Erik Schurink: “We gave a presentation every fortnight during the project with the technical findings and the decisions to be taken. This keeps the client well informed of the progress and gives confidence on both sides. This was an essential success factor for the smooth running of the project”.

Within Strypes there are various energy specialists active who all use the same approach. As a result, they work well together, sharing knowledge and continuously improving the approach.