Retrofit medium voltage switchgear

Medium voltage up to 36 kV – technical expertise at the highest level

(licensed partnership with Siemens AG)

We are your experienced partner in the field of medium voltage switchgear up to 36 kV that have been successfully implementing projects on behalf of Siemens AG for many years. Whether it’s new construction, series production, custom designs, or retrofitting, we offer solutions that are precisely tailored to the requirements of our customers and meet the highest standards of safety, efficiency, and longevity.

Niederspannungsschaltanlage mit Messinstrumenten und Steuermodulen in einem Industriebetrieb
Niederspannungsschaltanlage mit Messinstrumenten und Steuermodulen in einem Industriebetrieb
The requirements for medium-voltage systems are constantly increasing, with grid stability, security of supply, and system availability taking centre stage. To ensure these over the long term, we combine our practical expertise with state-of-the-art testing technology:
  • Impulse voltage tests up to 170 kV to simulate overvoltage events
  • AC withstand tests up to 70 kV to verify insulation strength
  • Partial discharge measurements in accordance with IEC 60270 to detect insulation damage at an early stage and prevent failures

These testing methods ensure that every system operates reliably, even under extreme grid conditions.

Switchgear technology in detail

We have extensive experience in the planning, manufacture, and customization of various Siemens switchgear types, including:

  • 8BK20 / 15 kV for special applications, e.g. for ÖBB (single-pole design, 16⅔ Hz railway power)
  • 8BD series (8BD1, 8BD2, 8BD3) for industrial networks and power utilities
  • BJ/K20, 8BK30, 8AA10+20, OH/GH211, 221, 223 for various applications in medium-voltage networks
  • Spare parts

In addition to standard production, we also develop custom designs, for example for:

  • Furnace switchgear systems for heavy industry
  • Cable boxes for complex network infrastructures
  • Busbar bridges for network coupling
  • Metering panels for precise grid monitoring

Retrofit – modern technology for existing systems

A key focus is the retrofit of older switchgear systems, which we also carry out as part of Siemens projects. In this process, we selectively replace critical components to improve operational safety and extend service life:
  • Replacement of circuit breakers with the latest-generation vacuum circuit breakers
  • Integration of modern switch-disconnectors for greater switching reliability
  • Adaptation to current protection and control technology, such as IEC 61850
  • Optimization of cooling and insulation systems for increased load capacity
A retrofit offers a cost-effective alternative to a new installation, reduces downtime, and simultaneously improves operational safety. Your advantage: comprehensive solutions from a single source From planning and project engineering through mechanical and electrical manufacturing to commissioning, testing, and service, we support the entire life cycle of your medium-voltage system. All our projects are carried out directly on behalf of Siemens AG and therefore represent the highest standards of quality, safety, and innovation in medium-voltage technology.
Niederspannungsschaltanlage mit Leistungsschaltern, Sammelschienensystem und eingezeichnetem Schaltplan

Technical specifications

Parameter Specification
Voltage level Medium voltage up to 36 kV
Impulse withstand voltage Up to 170 kV (impulse voltage test)
AC withstand voltage Up to 70 kV (AC withstand test)
Partial discharge measurement In accordance with IEC 60270
Protection and control technology IEC 61850-compatible
Scope of retrofit Circuit breakers, switch-disconnectors, protection relays, cooling systems, and insulation systems
Siemens series 8BK20, 8BD1/2/3, BJ/K20, 8BK30, 8AA10+20, OH/GH211/221/223
Partner status Licensed partner of Siemens AG
Manufacturing and installation SKS Elektroanlagenbau GmbH, Fohnsdorf, Styria

FAQ

What is a medium-voltage switchgear retrofit?

A retrofit involves replacing outdated or worn components in an existing medium-voltage switchgear system with modern technology without replacing the entire system. Typical measures include replacing circuit breakers with vacuum circuit breakers, integrating modern protection relays, and adapting the system to current communication standards such as IEC 61850. The result is a system with improved operational safety and an extended service life at significantly lower cost than a completely new installation.

A retrofit is generally more cost-effective when the existing system structure and switchgear enclosure are still in good condition and only individual components need to be replaced. Key factors include the age of the system, the availability of spare parts for the existing equipment, and the requirements regarding operational downtime. Before every project, SKS carries out a technical condition assessment to determine the retrofit potential and its economic viability.

The duration depends on the scope of the work and the downtime requirements. Replacing components in individual panels can be completed within a few days. More extensive projects involving the modification of multiple panels and the integration of new control technology are typically carried out during scheduled maintenance periods to minimize operational disruption. SKS coordinates the process with the operator.

SKS is a licensed partner of Siemens AG and has experience with the 8BK20, 8BD1/2/3, BJ/K20, 8BK30, 8AA10+20, and OH/GH211, 221, and 223 series. In addition, SKS develops custom solutions for applications outside Siemens’ standard product range, including furnace switchgear for heavy industry and railway power systems.