specification and testing

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Understanding Surge Arresters

Specification and Testing


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Content

Content

Surge Arrester Selection Parameters

Applicable Standards

Testing


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ABB GroupDecember 10, 2013 | Slide 3

IEC 60099-4 as the only valid standard just be sure it is the current edition

COV Uc no more than Um/3 needed (plus perhaps additional harmonics)

TOV important to be correctly determined and specified

Desired protection levels realistic and relevant

Line Discharge Class higher gives better protection for most important equipment

Energy demands realistic, relevant & well-defined; no unnecessary added margin

Environmental considerations ambient temperature, altitude, pollution, etc

Mechanical demands limited wherever possible by installation

Thereafter, manufacturer ideally to be given freedom to

optimize his design

higher COV is unnecessary

rated voltage not specified by user

Otherwise risk for sub-optimized solutions since users

cannot know design specifics


Surge Arrester Selection Parameters: AC Arrester Specification


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Surge Arrester Selection Parameters: Electrical

Electrical

selection

complete

Uc > Um/3


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Surge Arrester Selection Parameters: Mechanical

Mechanical

selection

complete


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How much insurance to buy?Choose the surge arrester that provides optimum protection with

suitability to the application at a value for money price and not simply

based on up-front cost.

Which Surge Arrester

can I afford not to choose?


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Content

Content



Testing


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IEC (International Electrotechnical Commission)

IEC 60099-4 (Edition 2.2, 2009-05) #)

"Metal-oxide arresters without gaps for a.c. systems

IEC 60099-5"Surge arresters - Selection and application recommendations

IEC 60071-1"Insulation co-ordination - Definition, principles and rules

IEC 60071-2"Insulation co-ordination - Application guide

IEC 60815-1, -2, -3"Guide for the selection of insulators in respect of polluted conditions"

IEEE (Institute of Electrical and Electronics Engineers) IEEE C62.11 (2012)

Metal-Oxide Surge Arresters for AC Power Circuits (>1 kV)

#) Forthcoming Edition 3 (prelim release 2014)

New concept of arrester classification and energy withstand testing Requirements and tests for UHV arresters




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Edition 1 only considered porcelain-

housed arresters and much testing of

ZnO arresters was based on the old

gapped arrester standard 99-1

Edition 2 2004

Polymer arresters now

considered

Amendment 1 2006

Edition 2.1

Short circuit testing defined

Amendment 2 2009

Edition 2.2

Mechanical testing defined Forthcoming Edition 3 (prelim release 2014) New concept of arrester classification

and energy withstand testing Requirements and tests for UHV arresters


Applicable Standards: IEC 60099-4 Development


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Residual voltage

Long duration current impulse withstand

Operating duty tests

Accelerated ageing

Insulation withstand

Short circuit

Sealing / moisture ingress (porcelain / polymer)

Mechanical

Weather ageing (polymer-housed arrester)

Artificial pollution (porcelain-housed multi-unit arrester)

Internal partial discharge / RIV

Environmental

Tests of arrester disconnectors

Current distribution test (multi-column)


Applicable Standards: Type Testing to IEC 60099-4 IEC 60099-4 defines well

the type tests to be

performed on

Elements

Sections

Complete design

to represent actual

performance

as applicable for

Individual test Design concept

DVD

MO RESISTOR

HOUSING

OTHER


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Content

Content



Testing


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Not all arrester manufacturersmake their own MO resistors bought as a commodity

Which block make is used

in a particular arrester?

Are arrester type test reports

available for every make of block

used? otherwise

published performance is worthless!


MO Resistors: Consider Source of Supply


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What are the routine and

sample tests on MO resistors

and what are the pass criteria?

How are claimed type test dataassured on a daily bases in

production?

How is the energy capability

defined and how is it assuredin daily production?

If some special energy capability is

claimed, how can it be traced back to

routine test requirements?


MO Resistors: Relevant Questions to Ask


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Are the MO resistors manufacturedin house or bought from anothermanufacturer?

If bought from others Are type tests performed on all block

types used?

How is the quality assured?

What steps are taken to ensure the

blocks have never been exposed tomoisture (eg. during transport)before being assembled in thearrester?

Are routine tests performed in-houseon the blocks bought or are onlydata from the supplier used for thedesign?


MO Resistors: Relevant Questions to Ask


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IEC60099-4, Amendment 2 (Ed. 2.0)Edition 2.2, 2009-05


Bending Moment

IEEE standard still remains behind the technology change(considers moisture ingress on polymer arrester but not effects of cyclical fatigue)



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Initialmeasurements

1000-cyclesat SLL

Bending momenttest at SSL

Test evaluation

Terminal torque

(30 sec)

Thermo mech

cycling (4x24h)

42 h in boilingsalt water

60-90 sec

Nm

42 hours

Boiling deionized water

with 1 kg/m of NaCl

1000cycles-SCL

1 cycle0.01-0.5 Hz

+SCL

SSL SSL

Time

+45 C

-25 C-40 C

Temp

24 h 48h 72 h 96 h

0 180 270 90

+60 C

Load direction:


Mechanical testing for polymer housings

Visual inspection

Measurement ofwatt losses

Partial dischargemeasurement

Measurement ofelectrical values

3 32

1

3 3

1


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Permissible deflection Focus should not only be on level of SLL & SSL

but also deflection under load

An arrester with insufficient stiffness againstmechanical load can jeopardize required

clearance distances leading to increased risk

for flashover with time

Through prudent designation of permissible loads,adequate clearances can be maintained under all

conditions to ensure deflection does not increase

during lifetime



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Only in the case of overload

Failure mode isinternal short-circuit

Explosive failure can resultif internal arc is notrelieved fast (< cycle)

Controlled external flashover

ensures personnel/equipmentsafety

Solid polymer designs must allow multipleperforations to externalise arc while holdingin internal components

Designs with enclosedair/gas volume requireventing devices to safely

relieve internal pressure



Short Circuit Safety


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Failure mode depends on arrester design:

Design A arresters have a design in which

a gas channel runs along the entire length ofthe arrester unit and fills 50 % of the

internal volume not occupied by the internal

active parts.

Design B arresters are of a solid designwith no enclosed volume of gas or having an

internal gas volume filling < 50 % of the

internal volume not occupied by the internal

active parts.

Uprefail >> Ur , 5+3 min

"External fuse wire"

along surface of activepart

Design A arresters

"Pre-failing"

by overvoltageapplication

Design B arresters

Active parts are ZnO-discs and spacers in series with them


Short Circuit Testing: IEC & IEEE Failure Modes


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Allowed to be found outside the circle

Fragments < 60 g from ceramic material like MO-varistors and/or porcelain

Pressure relief vent covers and diaphragms

Soft parts of polymeric material

Other parts inside circular enclosure

Allowed to be found outside the circle

Fragments < 60 g from ceramic material like MO-varistors and/or porcelain

Pressure relief vent covers and diaphragms

Soft parts of polymeric material

Other parts inside circular enclosure

H

d

h > 0,4 m

D = 1.2* (d + 2H) > 1,8 m

Circular enclosure D

Arrester unit

max. 60 g

No violent shattering Thermal breaking is allowed

Self extinguish within 2 min.



Short Circuit Testing: Pass Criteria and Set-Up


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Short Circuit Testing: ABB Safety Belt Winding



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Short Circuit Testing: Solid Design After Short Circuit Tests

with belt-windingwithout belt-winding


The belt-winding holds the

internal components in place.


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Counters exposed to same short-

circuit currents as the arrester

At present, no requirements inIEC 60099-4 for any form oftesting or verification

Performance depends on design



Short Circuit Testing: Surge Counters are in the Same Circuit


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Short Circuit Testing: Pass-Through DesignTo arrester

terminal

To ground

mA

Negligible additional residual voltage

Short-circuit safe no risk of explosive failure



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Selection Parameters - Keep to the Facts Electrical

Mechanical

Optimum Protection by Value for Money

IEC 60099-4 (Edition 2.2) Type testing Edition 3

Short Circuit Test Behaviour ABB Safety Belt Winding on PEXLIM

ABB Surge Counter Short Circuit Tested


Summary

Ensure the insurance you buy is what you need and

that it is verified through correct and necessary testing!


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