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ITU-T K.30 (12/2004)

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Self-restoring overcurrent protectors
Current-limiting protective devices are used worldwide to limit currents conducted by telecommunications wiring during high voltage faults on nearby power lines, due to electric traction systems, and from low voltage mains power contacts.
This Recommendation provides performance requirements for positive temperature coefficient (PTC) thermistors and contains information on coordination and application of self-restoring overcurrent protectors. These overcurrent protectors may be used inside the equipment to enable compliance with the requirements of the resistibility ITU-T Recs K.20, K.21 and K.45.
A PTC thermistor is mainly intended to limit overcurrents of relatively long duration and will normally have too slow a response time for switching transients or surges caused by lightning discharges, while semiconductor self-restoring overcurrent protectors (see Appendix II) have a faster response time than the PTC and will also operate for short duration surges.
Approval date: 2004-12-14
Approval process:AAP
Status: Superseded
Observation:Rec. ITU-T K.30 was deleted on 2011-03-14. Relevant parts were incorporated into ITU-T K.82 (05/2010).
Maintenance responsibility: ITU-T Study Group 5
Further details: Patent statement(s)
Development history
Ed. ITU-T Recommendation Status Summary Table of Contents Download
2 K.30 (12/2004) Superseded
1 K.30 (03/1993) Superseded -