Overview
EN IEC 61643-352:2018 (CLC) - Components for low-voltage surge protection, Part 352 - provides selection and application principles for surge isolation transformers (SITs) used in telecommunications and signalling networks. The standard applies to telecommunication transformer applications with signal levels up to 400 V peak-to-peak and describes SITs that have high rated impulse withstand voltages, with or without an electric screen between input and output windings. It focuses on SITs as surge protection components that mitigate onward propagation of common‑mode voltage surges. This document does not cover power line communication (PLC) transformers.
Key Topics
- Scope and definitions: Terms, symbols and abbreviations specific to SITs and telecommunication transformer applications.
- Service conditions: Environmental considerations such as temperature range, humidity, altitude and microclimate classification relevant to SIT selection and installation.
- Surge conditions: Characterisation of common‑mode and differential‑mode surges and the SIT role in mitigation and truncation of surge waveforms.
- Selection criteria: Guidance on choosing SITs based on impulse withstand voltage, rated values and coordination with the expected surge environment.
- Application principles: Installation practices, earthing/screening considerations, and system integration to limit onward surge propagation.
- Practical examples: Typical application scenarios including interbuilding links, substations, communication buildings, data centres, PoE systems and LAN installations.
Applications
EN IEC 61643-352:2018 is intended for engineers and specifiers involved in the design, selection and installation of surge protection in telecommunication and signalling environments. Typical users include:
- Telecommunication and network engineers specifying isolation and surge protection for lines and equipment.
- Substation and utility engineers protecting signalling links between control systems and field equipment.
- Data centre and IT infrastructure designers implementing isolation for sensitive network and PoE devices.
- Manufacturers of SITs and surge protection components developing products to meet selection and application requirements.
- Compliance and standards teams ensuring installations meet the IEC 61643 series guidance.
Practical benefits of following this standard:
- Improved resilience of telecommunication links to lightning and switching transients.
- Reduced risk of surge propagation between buildings or equipment racks.
- Clear criteria for matching SIT rated impulse performance to the expected surge environment.
Related Standards
- IEC 61643-351 / EN 61643-351 - Performance requirements and test methods for telecommunications and signalling network SITs.
- Other parts of the IEC 61643 series covering low-voltage surge protection components and systems.
Keywords: EN IEC 61643-352:2018, surge isolation transformers (SITs), telecommunication transformer applications, low-voltage surge protection, SIT selection, common-mode surges.
