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Technical guideFree to read2010

Sistemi statici di trasferimento (STS): nuovi standard per garantire le prestazioni e la sicurezza dei sistemi con la norma IEC 62310 (IEC 62310 for Static Transfer Systems)

Socomec · Matteo Granziero

An Italian-language Socomec white paper by Matteo Granziero on what the IEC 62310 product standard (parts 1-3, 2005-2008) changed for static transfer systems compared with relying on the UPS standard IEC 62040. The performance classification code, the test regime and neutral handling are its main topics.

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Overview

Before IEC 62310 (2008) there was no STS product standard, and IEC 62040 lacked definitions of preferred/alternate source, transfer/retransfer, synchronous/asynchronous transfer and sensitivity. STS are rated by current (A), not apparent power (kVA) as UPSs are. The paper shows how IEC 62310 fills this gap.

The classification code reads 'XX YY B ST'. CB means integral breakers/fuses, while PC withstands faults but cannot clear them. Neutral options are 00, NC (common), NS (switched) and NI (galvanically isolated). The switching mode is BB (break-before-make) or MM (make-before-break, which must be synchronous); T is the load interruption time and S the detection tolerance, graded 1-4 against ITIC-style tolerance.

IEC 62310-3 lists routine and type tests including backfeed, overcurrent breaking, short-circuit withstand, source tolerance and EMC. The overcurrent test applies overcurrent for at least 100 ms without damage, and the forced-ventilation test locks a fan rotor to check run time before shutdown. The paper also covers neutral handling in IT, TT, TN-S and TN-C earthing systems, required markings and maintenance-safety features such as backfeed protection.

Key points

  1. Before 2008 there was no STS product standard; IEC 62040 lacked source, transfer, synchronous/asynchronous and sensitivity definitions.
  2. STS are rated by current (A), not kVA as UPSs are.
  3. Class code 'XX YY B ST': CB (integral breakers/fuses) vs PC (withstands but cannot clear faults); neutral 00 / NC common / NS switched / NI galvanically isolated.
  4. Switching BB (break-before-make) or MM (make-before-break, synchronous); T interruption time, S detection tolerance, graded 1-4.
  5. IEC 62310-3 tests: backfeed, overcurrent breaking, short-circuit withstand, source tolerance, EMC.
  6. The overcurrent test applies at least 100 ms of overcurrent without damage.
  7. The forced-ventilation test locks a fan rotor to check run time before shutdown.

Using it in design

  • Give the STS catalogue fields for rated current (A), IEC 62310 class code (CB/PC, neutral NC/NS/NI, BB/MM, S and T grades) and backfeed protection.
  • Check neutral handling against the earthing system of both sources, for example a switched neutral where the sources have separate earthing.
  • Warn if MM transfer is selected with unsynchronised sources.

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Who should read it

Power-distribution engineers selecting STS and deciding source earthing and transfer behaviour.

Related standards

  • IEC 62310-1
  • IEC 62310-2
  • IEC 62310-3
  • IEC 62040-3
  • ITIC/CBEMA curve

Publication details

Authors
Matteo Granziero
Publisher
Socomec
Year
2010
Document number
WP STS 2010 IT
Document language
English
Source type
Manufacturer
Access
Free to read
Licence
Copyright retained; citation only — the publisher’s terms apply to the original document

Citation

Matteo Granziero (2010). Sistemi statici di trasferimento (STS): nuovi standard per garantire le prestazioni e la sicurezza dei sistemi con la norma IEC 62310 (IEC 62310 for Static Transfer Systems). Socomec. WP STS 2010 IT. https://content.voltimum.com/it/7277/whitepaper_socomec_sts_norma_iec_62310.pdf

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