Download Ethernet Surge Protective Device (SPD) Electrical Design

Ethernet Surge Protective Device (SPD)
Electrical Design Considerations
Presented by:
Mick Maytum
ICT Surge Protection Expert
ictsp-essays.info
Contents
• Surge types
Common-mode, Differential-mode unbalanced and balanced
• Ethernet system
• Unexpected consequences
Surge generators, Protective functions
• General
Port connections, Protective function
• Surge tests
Common-mode, Differential-mode, Common-mode to differentialmode conversion, Durability, Cable screen terminal
• DC tests
Insulation resistance, Voltage drop
• References
2/19/2017
Ethernet SPD Electrical Design
Considerations
2
Surge Types - Common-mode voltage
Equipotential conductor group
Reference potential
surge appearing equally on all conductors of a group at a given location
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Ethernet SPD Electrical Design
Considerations
3
Surge Types - Differential-mode voltage
a) balanced and b) unbalanced
Equipotential conductor group 1
Equipotential conductor group 1
A
Equipotential
conductor
group 2
Link
Reference potential
a)
Equipotential
conductor
group 2
B
b)
surge occurring between any two conductors or two groups of conductors
at a given location
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Ethernet SPD Electrical Design
Considerations
4
Surge Types - Differential-mode voltage
in an Ethernet system
1
PoE mode A
powering feed
pair
PoE mode B
powering feed
pair
Signal twisted pair
conductor to conductor
differential-mode surge
1
2
2
3
3
6
6
4
4
5
5
7
7
8
8
Powering pairs
pair to pair
differential-mode surge
Ref: Surges and their mitigation
Modes of PROTECTION and SURGE
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Ethernet SPD Electrical Design
Considerations
5
Ethernet system
• At surge frequencies the port loading is effectively
resistive capacitive and non-linear.
• The port Ethernet transformer presents a d.c. load of
about 1 W + 1 W
• The PoE PD circuits consists of a diode bridge, avalanche
diode and capacitance.
• The PoE PSE circuits consists of a regulating IC, series
pass element, some protection and capacitance.
• Most of the PoE PD and PSE ICs are rated about 100 V
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Ethernet SPD Electrical Design
Considerations
6
Unexpected consequences - Surge generators 1
Differential surge on Ethernet signal port
<2/>10, 800 V, 100 A
100 A
90 A
80 A
Generator current (green)
70 A
60 A
50 A
≠ (not the same result)
40 A
30 A
Secondary current (blue)
20 A
10 A
0A
0 µs
1 µs
2 µs
3 µs
4 µs
5 µs
6 µs
7 µs
8 µs
9 µs
10 µs
100 A
90 A
80 A
1.2/50-8/20 , 800 V, 100 A
Generator current (green)
70 A
60 A
50 A
40 A
30 A
Secondary current (blue)
20 A
(shorted secondary)
10 A
0A
0 µs
1 µs
2/19/2017
2 µs
3 µs
4 µs
5 µs
6 µs
7 µs
8 µs
9 µs
10 µs
Ethernet SPD Electrical Design
Considerations
7
Unexpected consequences - Surge generators 2
40 A
30 A
36 A
3)
Secondary
winding
energy
dump
1)
Linear
20 A
33 A
30 A
27 A
2)
Core
saturation
10 A
24 A
21 A
0A
0 µs
1 µs
2 µs
3 µs
4 µs
5 µs
18 A
15 A
40 A
1.2/50-8/20 (blue)
<2/>10 (red)
<2/>10 (red)
12 A
30 A
9A
20 A
6A
3A
10 A
1.2/50-8/20 (blue)
0A
0A
0 µs
0 µs
1 µs
2 µs
3 µs
4 µs
1 µs
2 µs
3 µs
4 µs
5 µs
5 µs
<2/>10, 800 V & 1.2/50-8/20, 1214 V
Refs: Ethernet differential surge testing - di/dt
Differential surge stress reduction by Ethernet magnetics
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Ethernet SPD Electrical Design
Considerations
8
Unexpected consequences – Gas Discharge Tubes - 1
RA
Equipment
port
A
RA
Equipment
port
A
RAB
RB
RAB
RB
B
Impulse
B
IB
IA
GDTB
GDTA
Impulse
GDTB
C
GDTA
C
9)
10)
GDTB conducts and hogs both conductor currents, IA & IB. The summation of GDTB arc
voltage and low voltage drop IA x RAB prevents GDTA sparkover . Equipment port suffers
a differential surge of IA.
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Ethernet SPD Electrical Design
Considerations
9
Unexpected consequences – Gas Discharge Tubes 2
RA
Equipment
port
A
RAB
RB
B
IB
IA
Impulse
GDTAB
C
11)
When the two outer GDT electrodes are independently surged, conduction of both halves occurs in well under 1 µs.
Low resistance Ethernet signal ports bridge the two outer electrodes lowering the non-conducting GDT section voltage.
The lower electric field voltage field takes longer to attract the conducting section plasma. As a result it can take many
microseconds before both GDT sections conduct. Before simultaneous conduction occurs, a major portion of the surge
front is applied differentially to the equipment port.
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Ethernet SPD Electrical Design
Considerations
10
Unexpected consequences – Gas Discharge Tubes 3
•
•
•
2/19/2017
Differential port voltage (cyan line, difference between
electrode voltages) and surge current (yellow line) for
generator voltages of 600 V, 1.5 kV, 2.5 kV and 6 kV.
Nominal GDT sparkover 1.1 kV.
Graphics created by Tatjana Gazivoda-Nikolic and kindly
supplied by Bourns Inc.
Ethernet SPD Electrical Design
Considerations
11
Unexpected consequences – Gas Discharge Tubes 4
RA
RA
Equipment
port
A
Equipment
port
IA
A
RAB
LAB
RB
B
RAB
RB
IB
D1
D3
RD
D5
ID
D
Impulse
LDE
GDTAB
RE
RDE
E
Impulse
D2
C
D4
D6
IE
GDTABDE
12)
C
Many simultaneous voltage limiting circuit solutions are available. The above two diagrams
show circuits using a multi-phase diode bridge and centre-tapped choke approaches.
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Ethernet SPD Electrical Design
Considerations
12
General - Port connections
• An SPD performance specification
should comprehend the
connector capability and not just
the internal component
capability.
• A hard-wire connector may be
required when the RJ45 contact
currents exceed 1 kA or voltages
between adjacent contacts will
exceed 4 kV.
2/19/2017
Twisted-pair
(1, 2) signal
1
Twisted-pair
(3, 6) signal
3
Twisted-pair
(4, 5) signal
4
Twisted-pair
(7, 8) signal
7
Cable screen
if present
2
1, 2 & 3, 6
PoE mode A
powering feed
pair
6
5
4, 5 & 7, 8
PoE mode B
powering feed
pair
8
Screen
Protective earth/
common
Ethernet RJ45 contact connections
Ethernet SPD Electrical Design
Considerations
13
General - Protective function
A generic Ethernet SPD performance specification should try to
be technology neutral on the surge protective components
(SPCs) used in the SPD.
SPD
1W
SPD
10 nF
10 nF
1W
75 W
1W
75 W
Termination
circuit
1 nF
Termination
circuit
1 nF
GDT common-mode voltage limiting
(partial circuit for only one twisted pair)
2/19/2017
1W
Isolating transformer common-mode voltage
blocking (partial circuit for only one twisted pair)
Ethernet SPD Electrical Design
Considerations
14
Surge tests - Common-mode
R1 through R8 = 1 W
C1 through C4 = 10 nF, 300V
Cable
port
R11 through R14= 75 W
Equipment
port
1
1
2
2
3
3
6
6
•
R1
C1
R11
C2
R12
C3
R13
•
•
R2
R3
R6
R9 = 5 W
SPD
•
R4
4
4
5
5
7
7
8
8
R5
Generator
charge
voltage kV
2.5
6
12
Manufacturer
defined
R7
1.2/50-8/20
combination
wave generator
C4
R14
R8
C5
PE
Screen
Screen
Termination
circuit
1 nF
3 kV
reference bar
Generator return/Earth
2/19/2017
a
b
c
Common source for maximum
stress on breakdown paths
Simulated Equipment port
Voltage limiting and isolation
technologies covered
DC tested after impulses
Maximum equipment
impulse limiting
voltage kV
1.0
1.5
2.0
Manufacturer
defined
d
Ethernet SPD Electrical Design
Considerations
15
Surge tests - Differential-mode single pair
R1 through R8 = 1 W
C1 through C4 = 10 nF, 300V
SW
(1-2)
R11 through R14= 75 W
Equipment
port
Cable
port
1
R1
1
C1
R11
C2
R12
R2
2
2
3
3
•
•
•
R3
SW
(3-6)
•
R6
6
R9 = 10 W
6
Differential
voltage
SPD
4
SW
(4-5)
R4
4
C3
R13
C4
R14
Generator
charge
voltage
kV
R5
5
5
7
7
8
8
R7
1.2/50-8/20
Generator
R10 = 10 W
SW
(7-8)
R8
Screen
C5
PE Screen
Termination
circuit
1 nF
3 kV
reference bar
Generator return/Earth
2/19/2017
Individual twisted pair tests
Simulated Equipment port
Simulated generator current
division
DC tested after impulses
a
b
c
d
Ethernet SPD Electrical Design
Considerations
2.5
6
12
Manufacturer
defined
Preferred measured values for
1-2, 3-6, 4-5 & 7-8
Termination
peak voltage
V
100
200
300
Manufacturer
defined
Termination
peak current
A
50
100
150
Manufacturer
defined
16
Surge tests - Differential-mode PoE pairs
PoE port
termination
Equipment
port
Cable
port
1
D1
D2
D3
D4
1
2
2
3
3
A
6
R9 = 10 W
C1
6
D5
A
SPD
B
SW
4
4
5
5
7
7
•
•
•
D6
D7
D8
D9
•
Individual PoE pair tests
Simulated Equipment port
Simulated generator current
division
DC tested after impulses
B
A
1.2/50-8/20
Generator
R10 = 10 W
B
8
Screen
C2
8
PE Screen
D10
reference bar
Generator return/Earth
2/19/2017
a
b
c
Ethernet SPD Electrical Design
Considerations
Generator
charge
voltage
kV
2.5
6
12
Manufacturer
defined
Preferred Peak
mode A or mode B
termination voltage
V
90
95
100
Manufacturer
defined
17
Surge tests - Common-mode to
differential-mode conversion – single pair
Generator
current sharing
network
Equipment
port
Cable
port
1
R1 = 40 W
Twisted
pair
differential
voltage
Termination
circuit
R12 = 150 W
1
•
•
R2 = 40 W
2
2
3
3
6
6
R3 = 40 W
R36 = 150 W
R6 = 40 W
R4 = 40 W
SPD
4
4
5
5
7
7
•
•
Individual twisted pair measurements
High impedance equipment port to
measure source voltage
Equalised generator current division
DC tested after impulses
R45 = 150 W
R5 = 40 W
R7 = 40 W
1.2/50-8/20
Generator
R78 = 150 W
R8 = 40 W
8
8
Screen
PE Screen
reference bar
Generator return/Earth
2/19/2017
a
b
c
Ethernet SPD Electrical Design
Considerations
Generator
charge
voltage
kV
2.5
6
12
Manufacturer
defined
Preferred values
of differential
voltage
V
100
200
300
Manufacturer
defined
18
Surge tests - Common-mode to
differential-mode conversion – PoE pairs
Generator
current sharing
network
Cable
port
1
R1 = 40 W
Termination
circuit
Equipment
port
R11 = 1 W
1
R2 = 40 W
•
•
R12 = 1 W
2
2
R3 = 40 W
R13 = 1 W
3
3
R6 = 40 W
R16 = 1 W
6
6
R4 = 40 W
Mode A
differential
voltage
•
•
Individual twisted pair measurements
High impedance equipment port to
measure source voltage
Equalised generator current division
DC tested after impulses
R14 = 1 W
SPD
4
4
5
5
R5 = 40 W
R15 = 1 W
R7 = 40 W
1.2/50-8/20
Generator
PoE
differential
voltage
R17 = 1 W
7
7
8
8
R8 = 40 W
Mode B
differential
voltage
R18 = 1 W
Screen
PE Screen
reference bar
Generator return/Earth
2/19/2017
a
b
c
Ethernet SPD Electrical Design
Considerations
Generator
charge
voltage
kV
2.5
6
12
Manufacturer
defined
Preferred values
of differential
voltage
V
90
95
100
Manufacturer
defined
19
Surge tests - Durability
• Little attention is given to impulse durability rather than
big number single impulse ratings
• Over life SPDs may experience many thousands of surges
not just one big one
• Further depending on the technology the single and
multi-impulse ratings maybe the same (silicon junction)
or require major rating reduction due to wear-out
(MOVs)
• It makes sense to know what the SPD 100 impulse or
more impulse rating is
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Ethernet SPD Electrical Design
Considerations
20
Surge tests - Cable screen terminal
Equipment
port
Cable
port
1
R9 = 5 W
SW
1
2
3
1
2
3
1.2/50-8/20
Generator
1
2
2
3
3
6
6
4
5
5
7
7
8
PE Screen
Screen
reference bar
2/19/2017
•
SPD
4
8
Generator return/Earth
•
•
b
•
Values based on IEC 60603-7-7
SW position 1 checks cable port screen terminal to
protective earth (PE) terminal bonding
SW position 2 checks equipment port screen
terminal to protective earth (PE) terminal bonding
SW position 3 checks cable port screen terminal to
the equipment port screen terminal.
Generator
charge
voltage
kV
2.5
6
12
Manufacturer
defined
Ethernet SPD Electrical Design
Considerations
Maximum screen
to PE voltage,
SW positions 1 & 2
V
40
90
180
Manufacturer
defined
Maximum screen
to screen voltage,
SW position 3
V
80
180
360
Manufacturer
defined
21
DC tests - Insulation resistance 500 V >2 MW
1, 2
3, 6
SW
7, 8
4, 5
1
1
2
2
3
3
1, 2
6
6
SW
3, 6
2
2
3
3
6
6
SPD
SPD
W
Equipment
port
Cable
port
1
Equipment
port
Cable
port
1
4
4
5
5
7
7
W
7, 8
4, 5
4
4
5
5
7
7
8
8
8
PE Screen
Screen
Screen
8
Screen
reference bar
reference bar
b
Isolating transformer SPD
Voltage limiting SPD
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Ethernet SPD Electrical Design
Considerations
22
DC tests - Voltage drop
Equipment
port
Cable
port
1
1
V12
2
2
3
3
6
6
V36
0.5 A
current
source
SPD
4
4
5
5
7
7
V45
V78
8
8
Screen
2/19/2017
• Important for PoE
• Preferred value < 0.5 V
• Then total d.c. power
feed mode A or B
series resistance of the
SPD < 0.5 W
PE
Screen
Ethernet SPD Electrical Design
Considerations
23
References 1 of 3
Ethernet differential surge testing - di/dt
Differential surge stress reduction by Ethernet magnetics
Surges and their mitigation
Modes of PROTECTION and SURGE
Voltages and currents in Ethernet cables due to lightning strokes
ETHERNET port surge testing – Test levels and configurations
Ethernet Surge Protective Device (SPD) design considerations
Recommendation ITU-T K.117 : Primary protector parameters for the surge protection of
equipment Ethernet ports
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Ethernet SPD Electrical Design
Considerations
24
References 2 of 3
Ethernet ATIS PEG Conference Papers 1999-2012
CD currently available of all 1999-2012 papers
ATIS PEG Conference 1999 Papers
10Base-T Surge Protection: Nisar Chaudhry
ATIS PEG Conference 2007 Papers
Power Over Ethernet (POE) – What is it? How to Protect it?: Mick Maytum
ATIS PEG Conference 2008 Papers
Ethernet Protection (Once it has Left the Building; Inside the Cell Site): Nisar Chaudhry
ATIS PEG Conference 2009 Papers
Electrical Protection Considerations for the Deployment of Ethernet Services in the Outside Plant: Larry Payne
ATIS PEG Conference 2010 Papers
Evolving Ethernet Applications and Protection: Jim Wiese
Ethernet Protection: Nisar Chaudhry
ATIS PEG Conference 2011 Papers
A Comparison of Various Ethernet Protection Solutions: Ben Huang
Lightning Damage of the Home Network Ports: Mick Maytum
IEEE Std. 802.3 Ethernet ports — Types, Surge Capability and Applications: Mick Maytum
ATIS PEG Conference 2012 Papers
ONT Damage: Jim Wiese
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Ethernet SPD Electrical Design
Considerations
25
References 3 of 3
Ethernet ATIS PEG Conference Papers 2013-2016
Currently downloadable at the PEG Library
ATIS PEG Conference 2013 Papers
Ground or Not to Ground Ethernet Protection, Part 2: Nisar Chaudhry
Optical Network Terminations (ONTs): Lightning Damage and Standards – What’s the Latest Information?: Jim Weise
The Ethernet Port Maze, Part 1: Michael (Mick) Maytum
The Ethernet Port Maze, Part 2: Michael (Mick) Maytum
ATIS PEG Conference 2014 Papers
Ethernet Protection-Latest Standards Work: Jim Wiese
GbE Port Protection in Exposed Environments: Len Stencel
ATIS PEG Conference 2015 Papers
Power Over Ethernet (PoE) Part 1- What Is It, How It Is Used, and Lightning Field Failure Analysis: Jim Wiese
Power Over Ethernet (PoE) Part 2 – Protecting PoE Against Intra-Building and OSP Environments: Tim Ardley
Latest ITU-T Surge Protection K Recommendations: Michael “Mick” Maytum
Direct Lightning Strike Surge Propagation in Customer Premises Wiring: Michael “Mick” Maytum
Lightning Surge Damage to Ethernet and POTS Ports Connected to Inside Wiring: Joe Randolph
ATIS PEG Conference 2016 Papers
Protecting PoE PSE and Ethernet to the Latest International OSP Standards: Tim Ardley
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Ethernet SPD Electrical Design
Considerations
26