Background

Our Partner, committed to sustainable development, is expanding its photovoltaic farms and upgrading its in-house power grid. This expansion required the addition of three new medium-voltage switchgears:

• A 30 kV switchgear to serve the photovoltaic farm, fed from the 110 kV GPZ and connected to the others via a 30 by 6 kV transformer.
• Two 6 kV rated switchgears for energy distribution and power supply to the plant.
• The Challenge

What challenges did our partner face?

Our Partner needed surge protectors for all three new medium-voltage switchgears. Our task was to select surge arresters to protect the following MV equipment:

• Switchboards.
• Cable lines.
• Transformers.

We identified two key hotspots specific to this project:

• Transitions between cable and overhead lines: These points can experience surges of multiplied value. Additionally, repairing damage to cable lines is labor-intensive and costly, necessitating careful design to secure these connections.
• Incoming connections to transformers: These connections, being overhead, required careful calculation of the appropriate set of surge arresters to protect the MV transformer effectively.

Additionally, the absence of an existing overvoltage protection design meant we had to create one from scratch. Moreover, some proposed installation locations did not meet the technical requirements, requiring adjustments to the surge arrester parameters.

Our Solution

We began by obtaining comprehensive technical documentation of the existing electrical network from our Partner, including facility photos. We also conducted two video conferences with the client’s technical team. Although we were ready to visit the implementation site, it was unnecessary in this case.

Our work included:

• Calculating the maximum operating voltage of the arresters.
• Selecting appropriate limiter models.
• Analyzing operating points around switches to determine the best locations.
• Defining protection zones to establish the extent of individual surge arrester sets.
• Determining installation locations based on technical conditions and the Partner’s requirements.
• Checking short-circuit conditions to ensure our solutions could withstand short-circuit currents according to standards.
• Manufacturing and delivering custom surge arresters with specific parameters.
• Providing technical documentation, including installation and operation instructions, and product data sheets.

We produced custom surge arresters specifically for our Partner’s needs. The process, from initial contact to the submission of a comprehensive offer, took approximately two weeks. From technical discussions to the delivery of surge arresters, the timeline spanned about six weeks, despite the Partner’s tender process.

Outcomes

The project was scheduled for completion by the end of April 2023, but by mid-March, some arresters were already installed and operational. Upon project completion, the Partner achieved reliable protection for the power supply installation to their industrial plants. The number of surge damages is expected to decrease. Additionally, our client gained a trusted partner, as evidenced by selecting Protektel for the supply of replacement transformers in their next project.

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