aa 02 short-circuit iec standard

8/14/2019 Aa 02 Short-circuit Iec Standard

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Short-Circuit Analysis

IEC Standard

SUPRIYANTO, ST., [email protected]

POWER SYSTEM

ANALYSIS USING ETAP


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APLIKASI KAJIAN/ANALISIS

Verifikasi kapabilitas /interrupting

capability peralatan proteksi.

Proteksi peralatan dari mechanical forces

yang besar (maximum fault kA)

Proteksi I2t terhadap peralatan (thermal

stress)

Pemilihan ratings atau setting relayuntuk tujuan koordinasi proteksi.


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JENIS GANGGAUN H.S.

1996-2009 Operation Technology, Inc.Workshop Notes: Short-Circuit IEC Slide 3


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Copyright Siemens AG 2007. All rights reserved.

Short-Circuit Calculations

Types of Short Circuits

3-phase

2-phase

1-phase


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Pola Umum Gangguan H/S


Pada Jaringan Industri :

IL-G> I3-phase adalah jarang terjadi ,

tipikal IL-G .87 * I3-phase , karenaumumnya gangguan tiga fasa

menghasilkan arus gangguan maksimum,

maka hanya gangguan 3 fasa yangdipertimbangkan.


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Types of SC Faults

Three-Phase Ungrounded FaultThree-Phase Grounded Fault

Phase to Phase Ungrounded Fault

Phase to Phase Grounded Fault

Phase to Ground Fault

Types of Short-Circuit FaultsJENIS GANGGAUN H.S.


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Q : Apa sebab pada jaringan industriyang dipertimbangkan hanya h.s.

Tiga fasa?


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Offset)(DCTransientStateSteady

t)-sin(Z

Vm)-tsin(Z

Vmi(t)

(1))tSin(Vmdt

diLRiv(t)

Re

expressionfollowingtheyields1equationSolving

i(t)v(t)


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DC Current

AC Current (Symmetrical) with No AC Decay



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AC Fault Current Including the

DC Offset (No AC Decay)



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Machine Reactance ( = L I )

AC Decay Current


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Fault Current Including AC & DC Decay


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IEC Short-Circuit Calculation (IEC 909)

Initial Symmetrical Short-Circuit Current (I"k)

Peak Short-Circuit Current (ip)

Symmetrical Short-Circuit Breaking Current (Ib)

Steady-State Short-Circuit Current (Ik)


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Definitions according IEC 60909 (I)

initial symmetrical short-circuit current Ik

r.m.s. value of the a.c. symmetrical component of a prospective (available) short-

circuit current, applicable at the instant of short circuit if the impedance remains at

zero-time value

initial symmetrical short-circuit power Sk

fictitious value determined as a product of the initial symmetrical short-circuit current

Ik, the nominal system voltage Unand the factor 3:

NOTE: Sk is often used to calculate the internal impedance of a network feeder at the

connection point. In this case the definition given should be used in the following

form:

"

kn

"

k IU3S

"

k

2

n

S

UcZ


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Definitions according IEC 60909 (II)

decaying (aperiodic) component id.c.of short-circuit

current

mean value between the top and bottom envelope of a

short-circuit current decaying from an initial value tozero

peak short-circuit current ip

maximum possible instantaneous value of theprospective (available) short-circuit current

NOTE: The magnitude of the peak short-circuit current varies in

accordance with the moment at which the short circuit occurs.


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Transformer Z Adjustment

KT -- Network XFMR

KS

,KSO

Unit XFMR for faults on system side

KT,S,KT,SOUnit XFMR for faults in auxiliary

system, not between Gen & XFMR

K=1Unit XFMR for faults between Gen &

XFMR


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Syn Machine Z Adjustment

KGSynchronous machine w/o unit XFMR

KS,KSOWith unit XFMR for faults on system side

KG,S,KG,SOWith unit XFMR for faults in auxiliary

system, including points between Gen & XFMR


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Types of Short-Circuits

Near-To-Generator Short-Circuit

Pada konsisi h/s ini mesin sinkron akan

mengakibatkan arus hubung singkat dua kali

lebih besar dari rating arus generator, atau suatukondisi hubung singkat yang mengakibatkan

motor synchronous dan motor asynchronous

kontribusi lebih dari 5% terhadap initial

symmetrical short-circuit current (I"k)without motors.


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H/S dekat Generator /Near-To-Generator Short-Circuit



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Near-to-generator short circuit

Ik Initial symmetrical short-circuit current

ip Peak short-circuit current

Ik Steady-state short-circuit current

A Initial value of the d.c component

IB Symmetrical short-circuit breaking current

tB

BI22


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Definitions according IEC 60909 (III)steady-state short-circuit currentIk

r.m.s. value of the short-circuit current which remains after the decay of

the transient phenomena

symmetrical short-circuit breaking current Ib

r.m.s. value of an integral cycle of the symmetrical a.c. component of the

prospective short-circuit current at the instant of contact separation of the

first pole to open of a switching device


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Definitions according IEC 60909 (III)steady-state short-circuit currentIk

r.m.s. value of the short-circuit current which remains after the decay of

the transient phenomena

symmetrical short-circuit breaking current Ib

r.m.s. value of an integral cycle of the symmetrical a.c. component of the

prospective short-circuit current at the instant of contact separation of the

first pole to open of a switching device


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Far-From-Generator Short-Circuit

This is a short-circuit condition during which the

magnitude of the symmetrical ac component ofavailable short-circuit current remains essentially

constant.


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Far-From-Generator Short-Circuit



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Purpose of Short-Circuit Values

Design Criterion Physical Effect Relevant short-circuit current

Breaking capacity of circuit

breakers

Thermal stress to arcing

chamber; arc extinction

Symmetrical short-circuit

breaking current Ib

Mechanical stress to

equipment

Forces to electrical devices

(e.g. bus bars, cables)

Peak short-circuit current ip

Thermal stress to equipment Temperature rise of electrical

devices (e.g. cables)

Initial symmetrical short-

circuit current Ik

Fault duration

Protection setting Selective detection of partial

short-circuit currents

Minimum symmetrical short-

circuit current Ik

Earthing, Interference, EMC Potential rise;

Magnetic fields

Maximum initial symmetrical

short-circuit current Ik


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Factor pada Perhitungan If

menghitung ip berdasarkan Ik

menghitung ib untuk (near-to-gen &

not meshed network)

q menghitung ibmesin induksi (near-to-gen & not meshed network)

Equation (75) of Std 60909-0, adjusting Ik for near-to-gen & meshed

network

min&maxcalc ik


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STUDI KASUS H/S IEC


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Maximum voltage factor is used

Minimum impedance is used (all negative

tolerances are applied and minimum resistancetemperature is considered)

When these options

are selected


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Minimum voltage factor is used

Maximum impedance is used (all positive

tolerances are applied and maximum resistancetemperature is considered)

When this option is

selected


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Voltage Factor (c)

Ratio between equivalent voltage &

nominal voltage

Required to account for:

Variations due to time & place

Transformer taps

Static loads & capacitances

Generator & motor subtransient behavior


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Calculation Method

Breaking kA is moreconservative if the option

No Motor Decay isselected


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IEC SC 909 Calculation



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DEVICE DUTY COMPARISON


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L-G Faults


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Symmetrical Components

L-G Faults


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Sequence Networks


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0

ZZZ

V3I

I3I

021

efaultPrf

af 0

gZif

L-G Fault Sequence Network Connections


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21

efaultPr

f

aa

ZZ

V3I

II12

L-L Fault Sequence Network Connections


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0

ZZ

ZZZ

VI

I0III

20

20

1

efaultPr

f

aaaa 012

gZif

L-L-G Fault Sequence Network Connections

Transformer Zero Sequence Connections


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Transformer Zero Sequence Connections


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grounded.

solidlyY/terhubungtorTransforma

atauGeneratorsjikaterjadidapatiniKasus

I

:makaterjadiinikondisiJika

&

:jikabesarlebihdapatG-LGangguan

an.membahayakyanggangguan

adalahphase-3gangguanumumSecara

f3

1

1021

fI

ZZZZ

Solid Grounded Devices and L-G Faults


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Zero Sequence Model Branch susceptances and static loads

including capacitors will be consideredwhen this option is checked

Recommended by IEC for systems withisolated neutral, resonant earthedneutrals & earthed neutrals with earthfault factor > 1.4


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Complete reports that include individual

branch contributions for:

L-G Faults

L-L-G Faults

L-L Faults

One-line diagram displayed results that

include:

L-G/L-L-G/L-L fault current

contributions

Sequence voltage and currents

Phase Voltages

Unbalanced Faults Display & Reports


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Percent DC Current Waveform

Transient Fault Current Calculation (IEC 61363)


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AC Component of Fault Current Waveform



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Top Envelope of Fault Current Waveform



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Top Envelope of Fault Current Waveform



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IEC Transient Fault Current Calculation



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Complete reports that include individualbranch contributions for:

L-G Faults

L-L-G Faults

L-L Faults

One-line diagram displayed results that

include:L-G/L-L-G/L-L fault current

contributions

Sequence voltage and currents

Phase Voltages

Unbalanced Faults Display & Reports


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aa 02 short-circuit iec standard

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