Many medium- and low-voltage switchgear systems in Austrian industrial facilities are between 20 and 35 years old. Spare parts are no longer available, protection relays rely on outdated technology, and a fault can bring the entire production process to a standstill. The question is therefore not whether action is required, but how: complete replacement or a retrofit of the existing system?
Both options have their merits—which one is right depends on the condition of the system, the available budget, and the operational requirements.
What is a switchgear retrofit?
In a switchgear retrofit, outdated or no longer available components are replaced while the existing enclosure and busbar system are retained. The main focus is typically on:
- Circuit breakers: Replacement of unsupported models with modern vacuum circuit breakers.
- Protection relays: Replacement of electromechanical or older digital relays with modern protection devices featuring communication interfaces.
- Control and auxiliary circuits: Modernization of wiring and terminal blocks.
- Measurement and instrument transformer technology: Replacement of outdated current and voltage transformers.
- Control and display elements: Replacement of mechanical instruments with digital displays.
The enclosure, busbars, and cable connections generally remain unchanged. This eliminates the need for extensive civil engineering work, cable installation, and long delivery times for new switchgear frames.
Retrofit or new installation: the key differences
| Criterion | Retrofit | New installation |
| Cost | 30–60% of the cost of a new installation, depending on the scope | Full costs for the system, installation, cabling, and civil engineering work |
| Downtime | Short shutdown windows; modernization can be carried out panel by panel | Longer production interruption, often requiring a shutdown lasting several days |
| Lead time | Shorter lead times, with no need to wait for new enclosures | 6–18 months, depending on the manufacturer and configuration |
| Space requirements | No additional space required | Modification of the switchgear room may be necessary |
| Technology level | Modern protection and control technology integrated into the existing enclosure | Completely new technology and the latest design |
| Compliance with standards | The existing system must continue to meet the requirements of IEC 62271-200 | Complete recertification in accordance with current standards |
| Recommended when… | The enclosure and busbars are in good condition, but spare parts are no longer available | The system is structurally damaged, power requirements are increasing significantly, or SF₆ replacement is being carried out |
Note on costs: The stated cost ratio (a retrofit costing 30–60% of a new installation) is a practical guideline and depends on the scope of the work, the system type, and the condition of the existing equipment. A reliable assessment and binding quotation always require an on-site technical inspection.
When is a retrofit the right decision?
A retrofit is particularly worthwhile when the following conditions apply:
- The enclosure is structurally intact: There is no corrosion damage, mechanical deformation, or arc-related damage to the main structure.
- The busbars are in perfect condition and meet the current requirements for rated current and short-circuit withstand capacity.
- Spare parts for circuit breakers or protection relays are no longer available or can only be obtained as used parts at high cost.
- Connection and space requirements remain unchanged: No new cable entries or modifications to the switchgear room are required.
- The system must remain operational: A production shutdown lasting several days for a completely new installation would not be economically viable.
When is a new installation necessary?
In the following situations, a complete new installation is the more technically and economically viable option:
- The system has suffered arc damage or shows structural damage that makes continued safe operation impossible.
- The site’s power requirements have increased significantly: New machinery, expansions, or process changes require higher rated currents or additional panels.
- The system is gas-insulated using SF₆ and is to be converted to SF₆-free technology in accordance with the F-Gas Regulation (EU) 2024/573. For very old GIS systems, a new installation may be more economical than an SF₆ conversion.
- The switchgear room is being renovated anyway or the system must be relocated to another site.
- The system is more than 35 years old and several major components have reached the end of their service life at the same time.
Typical process of a retrofit project
| Phase PDF | Content PDF |
| 1. Existing system assessment | Technical inspection of the existing system, including the condition of the enclosure, busbars, protection devices, and wiring. Review and documentation of the existing circuit diagrams. |
| 2. Concept and quotation | Definition of the retrofit scope: which components will be replaced and which will remain. Selection of new protection relays and circuit breakers. Review of compliance with applicable standards. |
| 3. Planning and engineering | Preparation of new circuit diagrams and bills of materials. Coordination with the operator regarding shutdown windows and the installation process. |
| 4. Manufacturing and preparation | Pre-assembly of the new components wherever possible. Preparation of the installation documentation. |
| 5. On-site installation | Panel-by-panel shutdown and replacement of components. The objective is to minimize downtime for each panel. |
| 6. Testing and commissioning | Electrical testing, including insulation measurements, functional testing of protection relays, and testing of interlocking systems. Preparation of the commissioning report. |
| 7. Documentation | Handover of updated circuit diagrams, test reports, and operating manuals. |
Switchgear Retrofit by SKS Elektroanlagenbau
SKS Elektroanlagenbau carries out retrofit projects for medium- and low-voltage switchgear from a wide range of manufacturers, completely independently of any specific manufacturer. Our key areas of expertise include:
- Medium-voltage switchgear: Replacement of circuit breakers and protection relays in air-insulated systems up to 36 kV.
- Low-voltage switchgear: Replacement of circuit breakers, motor protection devices, and measurement systems.
- In-house testing facility in Fohnsdorf: Comprehensive electrical acceptance testing prior to on-site installation.
- Professional installation by our own experienced technicians in Austria and on international projects.
Detailed information about our SKS services can be found here: Medium-voltage switchgear retrofit.
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