Table of Contents - K.147 (07/2025) - Protection of digital ports connected to balanced pairs of conductors

1	Scope
2	References
3	Definitions
	3.1	Terms defined elsewhere
	3.2	Terms defined in this Recommendation
4	Abbreviations and acronyms
5	Conventions
6	Overview
	6.1	General
	6.2	Network power delivery
	6.3	Twisted-pair data link and surge protector capacitance
	6.4	Twisted pair powering usage
	6.5	Link insulation
	6.6	Summary of link conductor usage
7	Link voltage, current and resistance values
8	Surges on network systems
	8.1	Surge coupling mechanisms
	8.2	Direct coupling – permanent
	8.3	Direct coupling – transient
	8.4	Magnetic coupling
	8.5	Electric and electromagnetic coupling
	8.6	Surge resistibility design approaches
9	[ITU-T K.44] and [ITU-T K.117] test circuits
	9.1	Test circuit overview
	9.2	Power fault resistibility
	9.3	RP link
Annex A – Ethernet surge test circuits based on ITU-T K-series Recommendations
	A.1	Introduction
	A.2	Ethernet port testing
	A.3	Testing of XDSL ports
Appendix I – Examples of Ethernet twisted pair DC power feeds
	I.1	Introduction
	I.2	Powering over one twisted pair
	I.3	Powering over two twisted pairs
	I.4	Powering over four twisted pairs
Appendix II – Networking evolution
	II.1	General
	Page
	II.2	Testing
Bibliography