ethernet surge protective device (spd) electrical design ... · presented by: mick maytum ict surge...

Presented by: Mick Maytum

ICT Surge Protection Expert ictsp-essays.info

Ethernet Surge Protective Device (SPD) Electrical Design Considerations

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 differential-mode 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


Considerations 3

Equipotential conductor group

Reference potential

surge appearing equally on all conductors of a group at a given location

Surge Types - Differential-mode voltage a) balanced and b) unbalanced


Considerations 4

Reference potential

Equipotential conductor group 1

Equipotentialconductorgroup 2

Equipotential conductor group 1

Equipotentialconductorgroup 2

A

B

Link

a) b)

surge occurring between any two conductors or two groups of conductors at a given location

Surge Types - Differential-mode voltage in an Ethernet system


Considerations 5

Ref: Surges and their mitigation Modes of PROTECTION and SURGE

1

8

7

5

4

6

3

2

1

8

7

5

4

6

3

2

PoE mode Apowering feed

pair

PoE mode Bpowering feed

pair

Signal twisted pairconductor to conductordifferential-mode surge

Powering pairspair to pair

differential-mode surge

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


Considerations 6

Unexpected consequences - Surge generators 1 Differential surge on Ethernet signal port

<2/>10, 800 V, 100 A

≠ (not the same result)

1.2/50-8/20 , 800 V, 100 A

(shorted secondary)


Considerations 7

0 µs 1 µs 2 µs 3 µs 4 µs 5 µs 6 µs 7 µs 8 µs 9 µs

0 A

10 A

20 A

30 A

40 A

50 A

60 A

70 A

80 A

90 A

100 A

10 µs

Secondary current (blue)

Generator current (green)

0 µs 1 µs 2 µs 3 µs 4 µs 5 µs 6 µs 7 µs 8 µs 9 µs

0 A

10 A

20 A

30 A

40 A

50 A

60 A

70 A

80 A

90 A

100 A

10 µs

Secondary current (blue)

Generator current (green)

Unexpected consequences - Surge generators 2


Considerations 8

0 µs 1 µs 2 µs 3 µs 4 µs 5 µs

0 A

10 A

20 A

30 A

40 A

2)Core

saturation

1)Linear

3)Secondary

windingenergydump


0 A

10 A

20 A

30 A

40 A

1.2/50-8/20 (blue)

<2/>10 (red)


0 A

3 A

6 A

9 A

12 A

15 A

18 A

21 A

24 A

27 A

30 A

33 A

36 A

<2/>10 (red)1.2/50-8/20 (blue)

<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

Unexpected consequences – Gas Discharge Tubes - 1

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.


Considerations 9

9)

C

ARA

GDTB GDTA

Equipmentport

Impulse

BRB

RAB

10)

C

ARA

GDTB GDTA

Equipmentport

Impulse

BRB

RAB

IB IA

Unexpected consequences – Gas Discharge Tubes 2

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.


Considerations 10

11)

C

ARA

GDTAB

Equipmentport

Impulse

BRB

RAB

IB IA


• 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.


Considerations 11


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.


Considerations 12

12)

C

ARA

GDTAB

Equipmentport

Impulse

D1

RB

RAB

D2

D3

D4

D5

D6

ARA

C

Equipmentport

Impulse

BRB

RAB

IB

IA

LAB

GDTABDE

DRD

ERE

RDE

IE

ID

LDE

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.


Considerations 13

Screen

1, 2 & 3, 6

PoE mode A

powering feed

pair

1

8

7

5

4

6

3

2

Twisted-pair

(1, 2) signal

Twisted-pair

(7, 8) signal

Twisted-pair

(4, 5) signal

Twisted-pair

(3, 6) signal

4, 5 & 7, 8

PoE mode B

powering feed

pair

Cable screen

if present

Protective earth/

common

Ethernet RJ45 contact connections

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.


Considerations 14

Terminationcircuit

10 nF1 W

1 W 75 W

1 nF

SPD

Terminationcircuit

10 nF1 W

1 W 75 W

1 nF

SPD

GDT common-mode voltage limiting (partial circuit for only one twisted pair)

Isolating transformer common-mode voltage blocking (partial circuit for only one twisted pair)

Surge tests - Common-mode

• Common source for maximum stress on breakdown paths

• Simulated Equipment port

• Voltage limiting and isolation technologies covered

• DC tested after impulses


Considerations 15

1.2/50-8/20

combination

wave generator

SPD

Generator return/Earth

ScreenPE

ba

reference bar

7

4

6

5

3

2

8

1

R9 = 5 W

Cable

portEquipment

port

R1 through R8 = 1 W

R1

R2

R3

R6

R4

R5

R7

R8

7

4

6

5

3

2

8

1

C1 through C4 = 10 nF, 300V

C1

C2

C3

C4

R11

R12

R13

R14

R11 through R14= 75 W

C5

1 nF

3 kV

Termination

circuit

d

Screen

c

Generator charge

voltage kV

Maximum equipment impulse limiting

voltage kV

2.5 1.0

6 1.5

12 2.0

Manufacturer defined


Surge tests - Differential-mode single pair

• Individual twisted pair tests


• Simulated generator current division



Considerations 16

SPD

ScreenPE

b

reference bar

Cable

port

Equipment

port

R1 through R8 = 1 W

R1

R2

R3

R6

R4

R5

R7

R8

7

4

6

5

3

2

8

1

C1 through C4 = 10 nF, 300V

C1

C2

C3

C4

R11

R12

R13

R14

R11 through R14= 75 W

C5

1 nF

3 kV

Termination

circuit

d

Screen

Generator return/Earth a

SW

(1-2)

SW

(3-6)

SW

(4-5)

SW

(7-8)1.2/50-8/20

Generator

R9 = 10 W

R10 = 10 W

7

4

6

5

3

2

8

1

c

Differential

voltage

Generator charge voltage

kV

Preferred measured values for 1-2, 3-6, 4-5 & 7-8

Termination peak voltage

V

Termination peak current

A

2.5 100 50

6 200 100

12 300 150




Surge tests - Differential-mode PoE pairs

• Individual PoE pair tests


• Simulated generator current division



Considerations 17

SPD

ScreenPE

b

reference bar

Cable

port

Equipment

port

7

4

6

5

3

2

8

1

Screen

a

7

4

6

5

3

2

8

1

c

A

B

A

B

SW


1.2/50-8/20

Generator

R9 = 10 W

R10 = 10 W

PoE port

termination

D1 D2

D3 D4

D5

C1

D6 D7

D8 D9

D10

C2

B

A


kV

Preferred Peak mode A or mode B termination voltage

V

2.5 90

6 95

12 100



Surge tests - Common-mode to differential-mode conversion – single pair

• Individual twisted pair measurements

• High impedance equipment port to measure source voltage

• Equalised generator current division



Considerations 18

SPD

ScreenPE

b

reference bar

Equipment

port

Screen

a c

Cable

port

7

4

6

5

3

2

8

1


1.2/50-8/20

Generator

R2 = 40 W

R3 = 40 W

R6 = 40 W

R4 = 40 W

R5 = 40 W

R7 = 40 W

R8 = 40 W

R1 = 40 WR12 = 150 W

7

4

6

5

3

2

8

1

Termination

circuit

Twisted

pair

differential

voltage

Generator

current sharing

network

R36 = 150 W

R45 = 150 W

R78 = 150 W


kV

Preferred values of differential

voltage V

2.5 100

6 200

12 300



Surge tests - Common-mode to differential-mode conversion – PoE pairs

• Individual twisted pair measurements

• High impedance equipment port to measure source voltage

• Equalised generator current division



Considerations 19


kV

Preferred values of differential

voltage V

2.5 90

6 95

12 100



SPD

ScreenPE

b

reference bar

Equipment

port

Screen

a c

Cable

port

7

4

6

5

3

2

8

1


1.2/50-8/20

Generator

R2 = 40 W

R3 = 40 W

R6 = 40 W

R4 = 40 W

R5 = 40 W

R7 = 40 W

R8 = 40 W

R1 = 40 W

7

4

6

5

3

2

8

1

Termination

circuit

PoE

differential

voltageGenerator

current sharing

network

Mode B

differential

voltage

Mode A

differential

voltage

R12 = 1 W

R13 = 1 W

R16 = 1 W

R14 = 1 W

R15 = 1 W

R17 = 1 W

R18 = 1 W

R11 = 1 W

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


Considerations 20

Surge tests - Cable screen terminal


kV

Maximum screen to PE voltage,

SW positions 1 & 2 V

Maximum screen to screen voltage,

SW position 3 V

2.5 40 80

6 90 180

12 180 360





Considerations 21

SPD

ScreenPE

b

reference bar

Cable

port

Equipment

port

7

4

6

5

3

2

8

1

Screen

7

4

6

5

3

2

8

1

1

2

SW


1.2/50-8/20

Generator

R9 = 5 W

3

1

2

3

• 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.

DC tests - Insulation resistance 500 V >2 MW

Voltage limiting SPD


Considerations 22

SPD

ScreenPE

b

reference bar

Cable

port

Equipment

port

7

4

6

5

3

2

8

1

Screen

7

4

6

5

3

2

8

1

W

SW

7, 8

1, 2 3, 6

4, 5

SPD

Screen

reference bar

Cable

port

Equipment

port

7

4

6

5

3

2

8

1

Screen

7

4

6

5

3

2

8

1

W

SW

7, 8

1, 2 3, 6

4, 5

Isolating transformer SPD

DC tests - Voltage drop

• 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


Considerations 23

SPD

ScreenPE

Equipment

port

Screen

Cable

port

7

4

6

5

3

2

8

1

7

4

6

5

3

2

8

1

V12

V36

V45

V78

0.5 A

current

source

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


Considerations 24

http://www.ictsp-essays.info/wp-content/uploads/2016/11/Ethernet-differential-surge-testing-dibydt.pdf






http://ictsp-essays.info/product/differential-surge-stress-reduction-by-ethernet-magnetics/

http://www.ictsp-essays.info/wp-content/uploads/2016/11/surges-and-their-mitigation-rev0-1.pdf

http://www.ictsp-essays.info/wp-content/uploads/2016/11/surges-and-their-mitigation-rev0-1.pdf

http://ictsp-essays.info/product/modes-of-protection-and-surge/

http://ictsp-essays.info/product/modes-of-protection-and-surge/

http://ictsp-essays.info/product/voltages-and-currents-in-ethernet-cables-due-to-lightning-strokes/

http://ictsp-essays.info/product/voltages-and-currents-in-ethernet-cables-due-to-lightning-strokes/

http://ictsp-essays.info/product/ethernet-port-surge-testing-test-levels-and-configurations/






Ethernet Surge Protective Device (SPD) design considerations

https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-K.117-201612-I!!PDF-E&type=items





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


Considerations 25

https://www.atis.org/docstore/product.aspx?id=24555



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


Considerations 26

http://www.atis.org/peg/library.asp

ethernet surge protective device (spd) electrical design ... · presented by: mick maytum ict surge...

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