Download The Ethernet Port Maze Part 2 -

The Ethernet Port Maze Part 2 Future standardization in the ITU-T and
IEC
Presented by Mick Maytum
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
Surge Protection 101 - Part 2
ITU-T
The ITU-T activity was described in the “2012 Updates to ITU-T
Recommendations for Telecommunication Equipment and SPDs”
presentation.
ITU-T Study Group 5, Question 2/5 (Protective components and assemblies)
has a proposed Recommendation of:
 Surge Protective Component Application Guide - Lightning Isolation
Transformers
It is likely the supporting test and performance Recommendation will also be
produced:
 Test requirements and performance criteria for Lightning Isolation
Transformers
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
2
Surge Protection 101 - Part 2
IEC
IEC Sub-committee 37B (Specific components for surge arresters and surge
protective devices), Working Group 3 (Performance requirements, test
methods and application principles for Lightning Isolation Transformers) is
working on two proposed Standards from Japan:
 IEC 61643-351: Components for low-voltage surge protective devices - Part
351: Performance requirements and test circuits for lightning isolation
transformers (LIT)
 IEC 61643-352: Components for low-voltage surge protective devices - Part
352: Selection and application principles for lightning isolation transformers
(LIT)
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
3
Surge Protection 101 - Part 2
IEC
Current Situation
Chaotic, because the current material :




Doesn’t differentiate between surge protective devices (SPDs) and surge
protective components (SPCs). SPDs are out of scope for IEC SC 37B
Covers not just the surge protective parameters but also other application
specific parameters like return loss.
Causes strong opposition from one US delegate who claims (a.c. mains)
isolating transformers have been around for ever and are not SPCs.
Has a poor scope.
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
4
Surge Protection 101 - Part 2
IEC
Example IEC 61643-351 scope
Proposed : LIGHTNING ISOLATION TRANSFORMERS (LITs) are used for applications
up to 1000 V a.c. or 1500 V d.c. in telecommunication or signalling circuits and in lowvoltage power distribution systems. They are defined as transformers with high impulse
withstanding voltage with/without shielding between the input and output windings. LIT
are used for surge protection only from an indirect lightning stroke. When assuming the
surge protection from a direct stroke, the measure against direct lightning is performed in
combination with suitable SPD. This standard defines test circuits and test methods for
determining and verifying the LIT surge parameters. Preferred performance values for key
parameters are given.
Rebuttal: LIGHTNING ISOLATION TRANSFORMERS (LITs) are used for power
frequency supply applications up to 1000 V a.c., high frequency switching mode power
supply applications with transformer voltage-time ratings of 50 mVs and signal transformer
applications with signal levels up to 400 V peak to peak. They are defined as transformers
with high rated impulse voltage with/without screening between the input and output
windings. LITs are used to mitigate the onward propagation of common mode voltage
surges. Differential mode voltage surges occur due to line unbalance, SPD operation,
selective direct lightning or flash-over. Differential mode voltage surges can be mitigated
by cable shielding or applying surge protection across the conductor pair. This standard
defines test circuits and test methods for determining and verifying the LIT surge
parameters. Preferred performance values for key parameters are given.
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
5
Surge Protection 101 - Part 2
IEC
Key Surge Parameters

rated impulse voltage:
impulse withstand voltage value assigned by the manufacturer to the
equipment or to a part of it, characterizing the specified withstand capability
of its insulation against transient overvoltages

Inter-winding capacitance (characteristic)

Core saturation voltage-time integral (signal transformer characteristic)

Insulation resistance (for rating verification) (characteristic)
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
6
Surge Protection 101 - Part 2
IEC
rated impulse voltage
rated impulse voltage is the highest expected surge voltage for a given environment. The
impulse withstand voltage of a specified value is the test voltage used to verify the
rated impulse voltage. The impulse withstand voltage verification level is higher than
the rated impulse voltage
IEC 60664-1, Ed. 2.0: Insulation coordination for equipment within low-voltage
systems - Part 1: Principles, requirements and tests
IEC/TR 60664-2-1 Ed. 2.0: Insulation coordination for equipment within low-voltage
systems - Part 2-1: Application guide -Explanation of the application of the IEC 60664
series, dimensioning examples and dielectric testing

impulse withstand voltage: highest peak value of impulse voltage of prescribed form
and polarity which does not cause breakdown of insulation under specified conditions
IEC 1.2/50 rated and test voltages
1.5 kV (1.751 kV), 2.5 kV (2.920 kV), 4.0 kV (4.923 kV), 6.0 kV (7.385 kV), 8.0 kV (9.847
kV), 12 kV (14.770 kV)
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
7
Surge Protection 101 - Part 2
IEC
Inter-winding capacitance
V
V
Hi
Hi
I
I
Capacitance
Bridge
Guard
V
Lo
I
Capacitance
Bridge
Guard
V
Lo
I
Inter-winding capacitance measurement of balanced secondary winding
transformer with screen
PROTECTION
ENGINEERS
GROUP CONFERENCE
Inter-winding capacitance measurement of unbalanced secondary winding
transformer with screen
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
8
Surge Protection 101 - Part 2
IEC
Core saturation voltage-time integral
Core saturation can truncate differential surges
Primary
Voltage
Pulse
Generator
Secondary
Voltage
50 %
Measuring core saturation volt-second integral
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
9
Surge Protection 101 - Part 2
IEC
Insulation resistance

insulation: that part of an electrotechnical product which separates the
conducting parts at different electrical potentials

insulation resistance: resistance under specified conditions between two
conductive elements separated by insulating materials
The test is often done at 500 V d.c. and the requirement is >100 M
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
10
Surge Protection 101 - Part 2
ITU-T & IEEE
Further reading
There is a long dissertation on isolation transformers, how they mitigate surges,
term definitions and key parameters at:
http://pes-spdc.org/content/isolating-transformer-surge-protective-componentspc
Also covered are two other forms of magnetic surge mitigation; the neutralising
transformer and common-mode choke.
PROTECTION
ENGINEERS
GROUP CONFERENCE
March 19-21, 2013
San Ramon, CA
DISTINGUISHED LECTURER
PROGRAM
11
Surge Protection 101 - Part 2