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International Telecommunication Union
ITU-T Study Group 5
The need for The need for special special
requirementsrequirementsTetsuya Tominaga
Technical Session on Home NetworksGeneva, 29/04/2011
ITU-TStudy Group 05
AC mains plugs in globalo There are many plugs in the worldo There is no earth terminal in Japanese type
Technical Session - Home Networks - Geneva
JAPANESE TYPE
ITU-TStudy Group 05
Japanese customer premises AC power
o Voltage: 100 V rmso Frequency:o • 50 Hz Eastern Japano • 60 Hz Western Japano Configuration: TT
Technical Session - Home Networks - Geneva
Each PE has each grounding rod
ITU-TStudy Group 05
Smart House is “Connected House”
47/3/2011 TTC WorkShop
SPD ： Surge Protective Device
OpticFiber
Smart Meter
Many kinds of equipment will be connected each other under the TT system.
ITU-TStudy Group 05
Bad installation and insufficient resistibility
57/3/2011 TTC WorkShop
SPD ： Surge Protective Device
OpticFiber
Smart Meter
Good installation and Adequate resistibility are needed.
ITU-TStudy Group 05
Philosophy of protection
67/3/2011 TTC WorkShop
SPD
SPD ： Surge Protective Device
OpticFiber
SPD SPD
Good Bonding (K.66) Additional Protection (K.66)
Adequate Resistibility(K.21,K.44,K.66,K.71,K.hnwr)
Classification of interface (K.75)
Good installation and Adequate resistibility of equipment
Who knows K.66? Is Japanese type grounding configuration special?
ITU-TStudy Group 05
77/3/2011 TTC WorkShop
Yes
No
Determine the power induction limits
Identify the equipment and the number and type of ports
Does the equipment have more than one
port type?
“Enhanced”
Are there unique problems requiring
high isolation values?
No
Yes
“Special” “Basic”
Are the power induction limits >
600 V?
Yes
No
Figure 1/K.hnwr - Flowchart for determining required level of resistibilityFigure 1/K.hnwr - Flowchart for determining required level of resistibility
Figure 1/K.hnwr - Flowchart for determining required level of resistibility
Selection for Required resistibility
(K.hnwr/Draft)Bad bonding configuration(K.66 For example, the bonding wire length >1.5m )
5.2 ResistibilityRecommendation K.21 has two levels of resistibility “basic” and “enhanced”. Specification EN 50468:2009 gives advice on the selection of “basic” and “enhanced”. EN 50468:2009 advises:For equipment having only external telecommunication ports the resistibility requirements are defined in ITU-T K.21 “Basic level”.For equipment having additional connections to networks e.g. power networks, the test levels are defined in ITU-T K.21 “Enhanced level”The required level of resistibility can be determined in Figure 1/K.hnw. Information on “Special requirements” is contained in K.44.
When the bonding configuration is not along with K.66
ITU-TStudy Group 05
Proposal: Special Resistibility(K.44, K.66,K.hnwr)
TEST
Telecommunic
ation line
longitudinal
Telecommunic
ation line
transverse
Mains power longitudinal
Mains power
transverse
Telecommunic
ation line –
Internal port
Mains power – Internal
port
Telecommunic
ation line – Mains power
line
Internal tel. Port
–Internal tel. Port
Internal tel. Port (L1-L2)
InternalEther Port
InternalUSB Port
Coax. Port
Lightning
Surge Test
13 kV 10/700
4 kV 10/700
10 kV combination
10 kV combination
13 kV 10/700
10 kV combination
13 kV 10/700
10 kV combination
10 kVcombination
4 kVCombinationCurrent
limit resistor =
50
10kV??
6 kV??
6.42kA10/350 K.75For SPD
Technical Session - Home Networks - Geneva
Table II.6-1/K.44 – Resistibility and safety requirements of customer premises equipment powered by mains power
The special level is already described in K.44 and K.66.The external port is optical fibre now.So, All telecom. Ports are “Internal”The proposal is adequate Internal port test levels
Proposal UnderStudy
ITU-TStudy Group 05
ConciderationCoordination of “protecters” and “Safety and Lightning
protection” are important.
97/3/2011 TTC WorkShop
A
N
E
Un safe methodClass II without earthed SPDs
A
N
E
Safe methodClass II with earthed SPDs
Safety and lightning Protection in no earth
FUSE
Safety = Breaking FuseMinimize of Damage ratio = No Breaking Fuse
SPD2
SPD1
The impedance is need for coordination between SPDs
V0
V1V2
Coordination of protection
o Resistibility of inherent IC’s or circuit is becoming smaller, so it becomes more difficult to prevent the damage.
o No Earth is Un safe?
ITU-TStudy Group 05
Bypass circuit and Safety standard
o Conflict between Safety standards (e.g. IEC 60950) and Lightning protection (Recommendation K.66 and so on).• Bypass circuits between AC mains and telecom ports
described in K.66 should be permitted in any case to protect telecommunication equipments against overvoltages.
• The protector operate voltage would be higher than the insulation test voltage. Unfortunately the safety standards, e.g. IEC 60950, do not allow voltage limiters to bridge supplementary insulation, double insulation or reinforced insulation.
Technical Session - Home Networks - Geneva
TD566 is describe in detail, please read them.
ITU-TStudy Group 05
117/3/2011 TTC WorkShop
Conclusion
o If we are to prevent damage to HNW equipment we need:• Adequate resistibility of equipment• Special resistibility of equipment, when the
equipment can not be controlled the installation environment.
• Correct classification and use of ports• Good installation practices• Correct earthing and bonding• Protection for external and internal ports as
necessary.
