Blog article
Looking for a replacement for SOULÉ / TRIDELTA CLS voltage-limiting devices (VLDs)? We have the solution!
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SALTEK Author of the article -
07. 10. 2026
SALTEK BLOG · VLD · RAILWAY INFRASTRUCTURE
Looking for a replacement for SOULÉ / TRIDELTA CLS voltage-limiting devices (VLDs)? We have the solution!
Many railway networks in Europe use SOULÉ / TRIDELTA CLS voltage-limiting devices (VLDs) to connect exposed conductive parts to the rail, to protect track circuits and in cathodic protection applications. These devices have served railway infrastructure reliably for decades, but in many installations they are now approaching the end of their technical and physical service life.
LIMITATIONS
Compared with modern VLDs, they also show certain design and operating limitations:
01leakage current of up to 50 mA at operating voltage;
02use of a protective element subject to ageing;
03difficult operating-status checks;
04the need for special inspection procedures in the field.
< 1 μA
virtually zero leakage current2 metres
operating-status verificationVLD 1
Class 1 voltage-limiting deviceEN
50526-2 · 50122-1
THE SOLUTION
SALTEK brings a modern replacement for these devices – SCG-S with contactless operating-status signalling.
SCG-S is the first to combine the function of a Class 1 voltage-limiting device (VLD) with contactless operating-status signalling. The new SCG-S allows a fast and reliable functional check of the device without restricting operation and without dismantling. Instant information on VLD activation and its transition to the low-impedance state significantly shortens maintenance response time and reduces the risk of unplanned outages.
CLASS 1 VLD · SCG-SVARIANTS
Signalling module colour by type
BENEFITS
The main benefits of SCG-S include:
- virtually zero leakage current (< 1 μA);
- contactless operating-status check without track closures and without dismantling the device;
- operating-status verification from a distance of up to 2 m;
- instant information on VLD activation and its transition to the low-impedance state;
- reduced effects of stray currents and longer infrastructure service life;
- lower operating costs (OPEX);
- compliance with EN 50526-2 and EN 50122-1.
The replacement of existing SOULÉ / TRIDELTA CLS devices and the selection of a suitable SALTEK VLD type must always take into account the traction system, the required protective function, the short-circuit conditions and the specific installation site.
CONTACT
If you are planning to modernise SOULÉ / TRIDELTA CLS devices, we will be happy to help with our technical expertise. Contact our technical support.
Or get in touch directly with Pascal Magon, who will help you choose the right replacement:
Technical support →PM
Pascal Magon
Business Development Manager – VLD · SALTEK
FRDEENCZHRSKPascal speaks French, German, English, Czech, Croatian and Slovak.
EmailPascal Magon→
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