Into-No.

RF 619-002 EReg. Page

7435 l

INFORMATIONFrom/Date

RF A, March 1985ASEA BROWN BOVERI

ASS Relays

SETTING CALCULA TIONS

for Ultra High Speed Line Protection type

RALZA

~

ASEA, 5-721 83 Västerås, Sweden

RF619-002 E

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CONTENTS

l GENERAL

SETTINGSECTION

2 THE DIRECTIONAL WAVE DETECTOR

2.12.2

2.3

Network model wave detector

Fault calculations

2.2.1 Line section end A2.2.2 Line section end B2.2.3 Useful network conditions

Setting calculations

2.6.1 Independent mode tripping2.6.2 Dependent mode tripping2.6.3 Neutral current controi mode tripping

3 SETTING THE NEUTRAL CURRENT MEASURING UNIT

SETTING THE IMPEDANCE MEASURING SECTION4

4.1 Impedance conversionConsiderations to the network configuration

Evolving fault measuring section setting

iI.3.1 Inductive reaches for zone l and zone 2iI.3.2 Resistive reaches for zone l and zone 2.iI.3.3 Determination of setting factors for zone l and

zone 2.iI.3.iI Determination of the setting factors for the zero

sequence compensationiI.3.5 Determination of the setting factors for the zero

sequence current 6/Y reconnection element

Under impedance starter setting

iI.iI.l Inductive and resistive reaches for zone 3iI.iI.2 Determination of setting factors for zone 3

~

4.4

~SETTING THE MEASURING ELEMENTS FOR SWITCHINTO FAULT

5

SETTING THE DELA y TIMERS6

6.16.2

6.46.56.6

Wave detector

Neutral current controi mode

Impedance measuring unit zone l

Impedance measuring unit zone 2

Impedance measuring unit zone 3

Neutral current measuring unit

RF 619-002 E

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SHUNT REACTOR SWITCHING SETTING

8 COMPUTER FACILITlES

DEFINITIONS9

REFERENCE PUBLICA TIONSolGENERAL The ultra high speed line protective relay type RALZA is a

complete line terminal with high speed primary protectiverelaying and delayedback-up relaying.

It is designed for three-phase tripping or selective single phasetripping in EHV and UHV networks.

The operating princip le combines the directional wave detectorprincip le with the impedance measuring princip le forming anoutstanding line protection for EHV and UHV networks.

The RALZA relay operates as a directional comparison relay in apermissive tripping scheme and therefore needs a communicationlink (PLC or microwave). This relay operation is called "depen-dent mode tripping" and "neutral current mode tripping".

For close-in faults, the RALZA relay can operate independentlyof the communication link. This lat ter type of operation is called"independent mode tripping".

The delayed back-up relayingcom munica tian link.

of theis also independent

The opera ting principle makes it possible to detect high resistiveearth faults.

Lines with series capacitors can be fully protected with theRALZA relay.

Detailed information on the RALZA relay is presented in publi-cation RF 619-001 E.

A 2SETTING THE DIRECTIONAL W AVE DETECTOR SECTION

2.1Network modetwave detectors Before setting the RALlA relay wave detectors, the changes in

current and voltage must be known for all types of fault. Thesechanges can be calculated on a steady state basis usingsymmetrical components and Thevenin's theorem.

RF 619-002 E

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The network can be reduced to a simple source impedance(ZA, ZB) and line impedance (ZL) model as shown in Fig. 1.

Definitions for abbreviations used can be found on page 24-26.

Fig.l. Line model, line end AF is the remote end of the protected line and A is themeasuring end.

2.2Fault calculations All types of faults ought to be calculated to find the minimum

and maximum 016.1' andÅU', as defined in Fig. l above. A simpleprocedure is shown in the following examples, assuming equalpositive and negative sequence impedances for the sources.

-32.2.1Line section end A For line section end A define:

Z1 = Z1A + Z1L

~Zo = ZOA + ZOLRF = apparent fault resistance = Rf x (1 +

Rf = phase-to-earth fault resistance = RK + RN

2RK = phase-to-phase fault resistance

Calculate the following changes in current and voltage:

RF 619-002 E

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Single phase-to-earth fault in phase LI (RN)

El2

(6I'LE)RN = ~Q-~- + RF

21 + 3

Two-phase fault in phases L2 and L3 (ST)

a2 -a E'(6I'LL)5 = -(6I'LL)T = 2 x -Zl-+~

:>

Two-phase-to earth fault in phases L2 and L3 (STN)

2 2, (a -I) (21 + RK) + (a -a) (20 + 3 RF)

(61 LLE)S = x El

(6I'LLE)T = x E'

Three-phase fauIt (LI, L2, L3)

E'61'3L = ~~K

Find the maximum and minimum changes in current and voltageaccording to the following.

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i:For the "independent mode tripping" the four types of faultlocated at the remote end from the relay to be set shall beanalyzed to find the maximum ch ange in current ~i in per unit(p.u.) value of rated current and the maximum change involtage ~u in per unit (p.u.) value of rated voltage. Themaximum 6i will then give the "independent mode tripping"setting "a" and the maximum 6u will give the setting "b".

Thus determine

= max (161'LE

161'3L )

61'6I'LLE s'max

and

~U' 6U'LL 6U'LLE, s' T'max

ii:For the "dependent mode tripping" three types of fault locatedat the remote end from the retar to be set shall be analyzed tofind the minimum change in current 6i in per unit (p. u.) valueof rated current and the minimum change in voltage 6u in perunit (p. u.) value of rated voltage. The minimum 6i will thengive the "dependent mode tripping" setting "a" and the mini-mum 6u will give the setting "b".

Thus determine

6PLLE[ T'61' 6PLLEmedium

S'

I '

and ~6U'LLE~U' medium , S' T'

~The "dependent mode tripping" detection level shall be set higherthan the expected current and voltage changes for internaIswitching operations or surge arrestor discharges.

iii:For the "neutral current controi mode tripping" the single phasefault located at the remote end from the relay to be set shall beanalyzed to find the minimum change in current 6i in per unit(p.u.) value of rated current and the minimum change involtage 6u in per unit (p.u.) value of rated voltage. Theminimum 6i will then give the "neutral current controi modetripping" setting "a" and the minimum 6u will give the setting"b".

RF 619-002 E

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Thus determine

fl I'min = mi", A. I'LE ,

ÅU' min

2.2.2Line section end B

~~ F or line section end Bdefine:

Zl = ZlB + ZlL

")

"'"-'Zo = ZOB + ZOL

.ZB + ZLRF = apparent fault reslstance = Rf x (l + -ZA-

Rf = phase-to-earth fault resistance = RK + RN

2RK = phase-to-phase fault resistance

---,

~ I E(..1.", B\N J

1/

II§

-J-~

Fig.2 Line model, line end BFl is the remote end of the protected line and B is themeasuring end.

RF 619-002 E

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tripping" ( 61 ) are: -

max

l.

2.

3.

~

4.

Minimum near end source impedancei.e. ZlAmin and ZOAmin"

Maximum remote end source impedancei.e. ZlBmax and ZOBmax.

Minimum line impedance, series capacitor in servicei.e. ZlLmin and ZOLmin"

Only a single line in service, all parallel lines out ofservice.

5.

Minimum fault resistance at the remote end. ~Network conditions which may be expected to give the changesin voltage determining the setting for "independent modetripping" ( 6u ) are:max

6.

7.

Maximum near end source impedancei.e. ZlA and ZOA .max max

Maximum remote end source impedancei.e. ZlB and ZOB .max max

Minimum line impedance, series capacitor in servicei.e. ZlL .and ZOL ..mm mm

All parallellines in service.

8.

9.~"=P-'Minimum fault resistance at the remote end.la.

Network conditions which may be expected to give the changesin current determining the setting for "dependent mode tripping"( 6 I d " ) are:me lum ~11. Maximum near end source impedance

i.e. ZlA and ZOAmax max

12. Minimum remote end source impedancei.e. ZlB .and ZOB .

mm mm

Maximum line impedance, series capacitors by-passedi.e. ZlL and ZOL

max max

All parallellines in service.

13.

14.

Internal switching operations or surge arrestor dis-charge.

15.

2.2.3Useful network conditions

Network conditions which may be expected to give the changesin current -determining the setting for "independent mode

RF619-002 E

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Network conditions which may be expected to give the changesin voltage determining the setting for "dependent mode tripping"( 6u d o ) are: .me lum

17.

18.

-

19.

Minimum near end source impedancei.e. ZlA .and ZOA ..

mm mm

Minimum remote ~nd source impedancei.e. ZlB .and ZOB ..mm mm

Maximum line impedance, series capacitor by-passedi.e. ZlL and ZOL .max max

Only a single line in service, all parallel lines out ofservice.

20. Interna! switching operations or surge arrestor dis-charge.

.

Network conditions which may be expected to give the changesin current determining the setting for "neutral current controimode tripping" (61 .) are:mm

21. Maximum near end source impedancei.e. ZlA and ZOAmax max

Minimum remote end source impedancei.e. ZlB .and lOB .

mm mm

23.

-

2~.

Maximum line impedance, series capacitors by-passedi.e. ZIL and ZOLmax max

All parallellines in service.

25. Maximum fault resistance at the remote end.

Network conditions which may be expected to give the changesin vo!tage determining the setting for "neutra! current contro!mode tripping" (~U .) are:mm

26.

27.

28.

Minimum near end source impedancei.e. ZIA .and ZOA ..mm mm

Minimum remote end source impedancei.e. ZIB .and ZOB ..mm mm

Maximum line impedance, series capacitor by-passedi.e. ZIL and ZOL .max max

Only a single line in service, all paraliei lines out ofservice.

29.

30.

Maximum fault resistance at the remote end.

RF 619-002 E

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The setting calculations shall normally consider only the worstpractical case since academical parameter values may give a toosensitive setting. Rlease als o nate that minimum 6 i andminimum D. u, maximum Å i and maximum 6 u are not obtainedwith the same parameters.

When the change in current 6 I and in voltage .6. U are nowestablished for bus A and bus B the RALZA relay wave detectorsettings can be determined.

2.3Setting calculations

The RALZA relay accuracy is +25 % of set value +0.3 scaledivisions for "independent mode tripping" and =- 15 % of set value+0.3 scale divisions for "dependent mode tripping" and "neutralcurrent control mode tripping".

T o cover for possible errors in the fault calculations and therelay accuracy, a safety factor of 0.85 is introduced in thesetting calculations for the "neutral current controi modetripping" settings.For the "independent mode tripping" settings the safety factor isalready introduced in the relay operation principle and no further"reduction" is done in the setting calculations.

Two more correction factors are added to the setting calcu-lations

I Un nk = ~I and n = U" wheren n

I = CT secondary rating, I " = RALZA nominal currentn n

U = VT secondary rating, U "= RALZA nominal voltagen In

~2.3.1

~ndependent mode trippingThe settings for the "independent mode tripping" are made ontwo multiturn potentiometers with scale markings 0.0 to 99.8 onthe relay unit RXPA 2H in position A 525.

~ I is set on the top potentiometer marked "a"max

~ua

is set on the bottom potentiometer marked "b"max

-~I10 x -~~~---1

In

a=2 xk lowest re-commendedsettingis ~O.O

'-- J

Å ~~- -5

Un -b:: 1100

I

--xn

J

RF 619-002 E

Il2.3.2Dependent mode tripping

6~iuma=2 10 x -I] x kIn

lowest re-commendedsettingis 8.0

b= 100 xn lowest re-commendedsettingis 5.0

2.3.3Neutral current controi mode tripping

The settings for the "neutral current controi mode tripping" aremade on two multiturn potentiometers with scale markings 0.0to 99.8 on the relay unit RXPA 2H in position A 549.

b= 100~ Umin -5

-u;;--x 0.85 x n

il I .is set on the top potentiometer marked "a"mm

A U .is set on the bottom potentiometer marked "b"

mm

RF 619-002 E

123SETTING THE NEUTRAL CURRENT MEASURING UNI T

The setting for the RALZA relay neutral current measuring unitis made on a potentiometer on the relay unit RXIB 22 in positionA 1143.

The potentiometer is continously adjustable from l to 3 times ascale constant of 0.1 A, 0.25 A and 0.5 A for l Arated currentand 0.2, 0.5 and l A for 5 Arated current.

We normally recommend that the RXIB2 is set higher than theunbalance current caused by line section internai switGhingoperations.

'-I-

SETTING THE IMPEDANCE MEASURING SECTION

8.1"'-rmpedance conversion Before setting the RALZA relay impedance measuring section

the line section impedance shall be converted to the secondaryside of the instrument transformers as foliows:

U I'n nZ =- x-x Z. I d .sec UI I prim I = rate primary currentn n n

UI = rated primary voltage to neutraln

In = rated secondary current

Un = rated secondary voltage to neutral

4.2Considerations to the network configuration

The transient overreach of the impedance measuring elements issmall in bot h inductive and resistive direction. However, in orderto allow for errors in calculated or measured impedances of theline section, as weIl as angular er rors and ratio errors in the CT'sand VT's, the reach of zone l is normally recommended to be setto cover 80 per cent of the line section.

The reach of zone 2 is normally recommended to be set to cover120 per cent of the own line section. The reach must withsufficient margin, be shorter than the reach of zone l of therelay protecting the shortest line in the remote end station. Amargin of 10 to 20 per cent is recommended.

~

dIn a network with lines tied at an intermediate location as shownin Fig. 3 consideration has to be taken to the increase inmeasured impedance due to the power fed into the system at theintermediate location. In case of a fallit at point F, the relay atpoint A senses the impedance

~-~lA

z = ZL l +

where lA and IC are the fault currents from station A and C

respectively, ZLl is the impedance of the first line section and

ZF is the impedance of the second line section up to the fault

location.

Assume that the reach of zon e 2 of the retar at A is set to 80per cent of the apparent impedance seen by the retar in case ofa fault at the end of the set reach for zone l of the retar at B.

RF 619-002 E

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Assume that the reach of the first zone of the relay at B is 0.8time.s ZL2 where ZL2 is the impedance of the second linesectlon.

The impedance seen from station A up to the reach limit of thefirst zon e of the relay at B corresponds to the impedance

ZL

The reach of the second zone of the relay at A is normally notset beyond 80 per cent of the apparent impedance at the limit ofthe first zone of the relay at B, thus

z = 0.8 ICZLl + 0.8 (1 + ~) ZLL

-IWhen calcula ting the sett in g, the lowest value of ~ which canoccur should be considered. A

-G

-

Fig. 3 Network with lines tied at an intermediate location

The reach of zone 3 is normally recommended to be set to cover200 percent of the own line section. The apparent increase ofmeasured impedance due to power fed into the system as shownabove should be taken in to consideration. Since the zon e 3impedance measuring element is used also a a starter dueconsideration must be taken to the load impedance.

RF 619-002 E

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~.3Evolving fault measuring section setting

4.3.1Inductive reaches for zone l and zone 2

The inductive reach of zone l is given by the formula

X 3.2 fl=Ix3Qn

ax-PI

where X l = secondary inductive reach

I = rated current of the relayn

f = rated frequency (50 or 60 Hz)

a = current factor setting (5 6 ...99)

P l = voltage factor setting (5, 6 ...99)

The inductive reach of zone 2 is a multiple of the reach of zonel and is given by the formula

"""""

The factor "a" is set by means of the top two thumbwheel-switches each settable 0-9 at the front of unit RGAA 030 inposition B 134.

The multiples of 10 is set on the upper of the two switches. Forinstance, the factor 42 is obtained by setting 4 on the upperswitch and 2 on the lower one.

NOTE: The factor "a" should not be set lower than 5, althoughthe range 0-4 is available on the switch.

~The factor "PI" is set by means of the top two thumbwheel-switches, each settable 0-9 at the front of unit RGAB 030 inposition B 137. The multiple of 10 is set on the upper of the twoswitches.

~The factor "P2" is set by means of the middle two thumbwheel-

switches, each settable 0-9 at the front of unit RGAB 030 inposition B 137. The multiple of 10 is set on the upper of the twoswitches.

4.3.2Resistive reaches for zone l and zone 2

The resistive reach of zone l is given by the formula

R -3.21- I n

bx -ohms/phase

PI

RF619-002 E

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where Rl = secondary resistive reach

I = rated current of the retarn

b = current factor setting (5, 6...99)

P l = voltage factor setting (5, 6...99)

The resistive reach of zone 2 is a multiple of the reach of zone land is given by the formula

PIR2 = R I x P2

.

The factor "b" is set by means of the lower two thumbwheel-switches at the front of unit RGAA 030 in position B 134-. Themultiples of 10 is set on the upper of the two swiches.-NOTE:The factor "b" should not be set lower than 5, although

the range 0-4 is available on the switch.

The "p" setting is for each zone common for both the inductiveand the resistive reach.

4.3.3Determination of setting factors for zone l and zone 2

Generally, a high setting value is desirable for the settingfactors "a", "b" and "p".

1)

-

e

X2Calculate the ratio X where Xl and X2 arel

the desired inductive reach set tings for zone 1 and zone 2respectively.

X RThe figure i- is also valid for the ratio -i-. Hence, when

1 1determining the resistive reach setting of zone 1,

Xcheck that the zone 2 resistive reach R2 = -f x RI gives a

sufficient margin to the minimum load impedaÅce.R

The ratio -f should not be set higher than necessary.l

Usually aratio between l and 3 is satisfactory and the ratiomay be maximum 3-4 time

RF 619-002 E

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2) Calculate the setting factors "a", "b" and "PI" for zone I.

) < 3.2 x fa WhenXI 150nx

CalcuIate a' = Xl x In x 50 x 99

3.2 x f

Xla" = 99 x Rl

Calculate the actual value of: p = ~_3.2 x f x a-l Xl x In x 50

and round off to the nearest integer.

~

Calculate b =RI x In x PI

-3.2 -~nd round off the nearest

mteger..3.2 ~!b) When Xl> I x 50

n

Assume a = 99

Calculate: p' = ~3.2 x f x 99X 1 x In x 50

99 x 3-~Rl x In

p" =

'o

Choose the lowest of these two figures as factor "Pi"and round off downwards to the nearest integer.

g

and round off to the nearest integer.

R l x In x p lCalculate: b = 3.2 and rou~d off to the

nearest mteger.

3)

RF 619-002 E

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4) Check the calculated setting factors by inserting the figuresin the formulae for Xl' X2' and RIo

5) Make the settings for zone 1 and zone 2 on the thumbwheelswitches at the front of units RGAA 030 in position B134and RGAB 030 in position B137.

4.3.4Determination of the setting factors for the zero sequence compensation

The zero sequence compensation factor KN is determined fromthe formula

Xo -X lKN = --3X~

8

where Xl = positive sequence reactance of the line in ohmsper phase

Xo = zero sequence reactance of the line in ohms per

phase

The compensation factor is set by means of the top thumbwheel-switch at the front of unit RGGB 030 in position B131, acc. to

KN=YxO.lwhere y = number set on the thumbwheel-switch

= O, 1, 2,...15lj..3.5Determination of the setting factors for the zero sequence current 6/Y reconnection unit

This unit measures the residual current and we normallyrecommend a setting of 0.2 x IS. This means that the pro-

gramming switch Slj.:2 on unit RGIC 030 in position B128 shall bein the closed position.

The IS setting is made by means of the top thumbwheel-switch atthe front of unit RGIC 030 in position B128.

The operating current is set in accordance with the formulabelow. We normally recommend that the Ks setting is choosen to1 and therefore X to O.

x x 0.2 + l x In

I = K s x I =s n

where In = rated current of the relay

x = number set on the thumbwheel-switch

= O. l. 2 15

RF 619-002 E

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4.4Under impedance starter setting

4-.4-.1Inductive and resistive reaches for zone 3

The reach setting of the zone 3 impedance measuring unit iscalculated on basis of the positive sequence impedance Z1L in

ohms/phase in order to coordinate with the setting of theimpedance measuring units for zone 1 and zone 2. The reach isdifferent for different types of fault.

A modified lens characteristic with a characteristic angle of 600is osed to obtain a suitable margin between the reach of thezone 3 impedance measuring unit and the load impedance, seefig 4.

xohmsperphase

~angle

~-~/~~~ '/ ZLOAO~4 _R

/ ohms/ per./' phase

~~1)~,~

~ 30 jZi

~

1. Impedance measuring unit zone 1

2. lmpedance measuring unit zone 2

3. lmpedance measuring unit zone 3

a) Normal conditions and 3-ph. iaults

b) Line to line faults and earth-faults

with ZOL-Z1L =1

3Z1L

Fig.4 Impedance measuring section characteristics

RF 619-002 E

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The reach in the forward direction of the zone 3 impedancemeasuring unit is:

0.2 x f

I x -a

z -f - Ax -ohms/phase at 3-phase faultB

3

Z -0.2 x ff- ---x

I x 2a

A-ohms/phase at 2-phase faultB

0.2 x f A /Zf = x -ohms phase at l-phase faultI (l+K) Ba

where

f == rated frequency

I = rated currenta

KOL -ZlL

3 ZlLK:::

In the reverse direction the reach is

Zr = -o x Zf

The factor "A" is set by means of a switch to 5, 10, 20, 40 or 80ohms at the front of unit RXZK 4 in position A 507.

The factor "B" is set by means of three potentiometers (on e ineach phase) each settable 4.5-10.5 at the front of unit RXZK 4in position A 507.

The factor "D" is set by means of three potentiometers (on e ineach phase) each settable -0.2 to + l at the front of uni t RXZK 4in position A 507.

lf.4.2Determination of setting factors for zone 3

The forward reach Zf is normally recommended to be 2 times theown line section, but a check must be performed, as describedbelow, to discover potentialload encroachment.Calculate the minimum load impedance Z l d ( . ) in ohms per

.oa mmphase for different an gles of Smax'

U2Zl d ( . ) = Soa mm max

u = line voltage in kVwhere

s = max. apparent load in MY Amax

for different angles of Smax.

RF 619-002 E

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the zone 3 impedanceMax permissible 3-phase reach ofmeasuring unit in ohms per phase is

2 = 0.5 x 21 d ( . )max oa mm

P lot the minimum lo ad impedance in the impedance diagram.

The operating characteristic of the zone 3 impedance measuringunit can be constructed with the aid of the formulae in fig. 5. Wenormally recommend that 2r = -0.3 2f' which means that "D"-

setting is normally choosen to 0.3.

The operating characteristic for 3-phase faults is obtained by

increasing the figure by the factor"* = 1.15 and rotating it 300

anticlockwise around origo (O), see Fig.4.

'~

'...

Q

:;:>

Fig. 5 Zone 3 impedance measuring unit.

The appropriate values for Zf and Zgraphically.

are suitable determinedr

RF 619-002 E

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Calculate the ratio ~(KN = .lob -ZJ~~

3Z1L )a)

A 2IaB = Zf x f X 0.2-

b)(KN as above)

when KN > l

A (l + KN) laB = Zf x f- x -0.2- --

where KN is the zero sequence compensating factor see clause4.3.4 above and la is the rated current..

Choose asetting factor A equal to or less than 10 times the

calculated ratio ~ (nearest settable number)

Insert the selected value of A in the actual formula acc. toabove and calculate the B-factor.

Insert the calculated figures for A and B in the formula andcheck that the chosen value Zf is obtained, i.e.

f x 0.2 AIX2xBa

f x 0.2 AIa l

5SETTING THE MEASURING ELEMENTS FOR SWITCH INTa FAUL T

The RALZA relay impedance measuring element for zone 3 willdetermine the relay reach for a switch into fault condition.

The switch into fault logic also requires a low phase voltagecriteria "d" which is set by means of a potentiometer at thefront of unit RXEDB 2H in position A 937.

8

The operating level "d" for low phase voltage is set in accor-dance with the formula

Ud -set

-U n

where U t~ 0.85 Use nmin

U n .is the minimum line voltage to be expected.mm

RF 619-002 E

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6SETTING THE DELA Y TIMERS

6.1.Wave detector The setting for the tripping delar in the "dependent mode" and

the "neutral current controi mode" is made on one multiturnpotentiometer with scale markings 0.0 to 99.8 x 0.3 ms on thefront of unit RXTEH 2H in position A 519. The potentiometer islabeled "td".

Since the RALlA relay is used in a "permissive tripping scheme"we normal1y recommend that "td" shall be set to the channelnominal transmission time.

.;f;2~eutral current controi modeThe setting for the "neutral current controi mode" delar is madeon switch 51:4 in the front of unit RXTEN 2H in position A 555.

When the switch is set to the closed position a delay ofapproximately 20 ms is introduced to cover for arrestor dis-charge.

When the switch is set to the open position a delar of approxi-mately'*'O ms is introduced. Hence when switched series capa-citors are included in the protected line section we normallyrecommend that the switch SI:'*' is set to the open position tocover for unsymmetrical breaker pole switching.

6.3Impedance measuring uni t zone l

The setting is made to dela y the zone l impedance measuringunit until the series capacitor gaps flash over during a fault.Normally we recommend a setting of 50 ms.

When series capacitors are not included in the power system asetting of 35 ms will be sufficient.

~The setting is made by means of two thumbwheel-switchessettable 1-99 x l ms at the front of unit RXKE l in positionA 949. The multiples of 10 is set on the left of the two switches.

~ack-up delar :d6.4Impedance measuring element zone 2

The setting for the impedance measuring element zon e 2 is madeby means of the top thumbwheel-switch settable 0-15 x 50 ms atthe front of uni t RGT A 030 in position B 140.

We normally recommend a setting of 300-400 ms which means athumbwheel position of 6 or 8.

The corresponding switch "T2" at the front of module RGT A 030shall be in position "ON".

The switch "T3" at the front of unit RGT A 030 shall be inposition "OFF".

RF 619-002 E

23

6.5Impedance measuring element zone 3

The setting for the impedance measuring element zone 3 is madeby means of the bottom thumbwheel-switch settable0-15 x 400 ms at the front of unit RGT A 030 in position B140.

We normally recommend a setting of 800 ms which means athumbwheel position of 2.

The corresponding switch "T4" at the front of unit RGTA 030shall be in position "ON".

6.6Neutral current measuring unit

The setting for the neutral current measuring unit is made bymeans of two thumbwheel-switches settable 1-99 x 0.1 s at thefront of unit RXKE l in position A 943. The multiples of 10 is seton the left of the two switches.

We normally recommend a setting of 1.5-5 s which means athumbwhee1 position of 15-50.

7SHUNT REACTOR SWITCHING SETTING

When a shunt reactor is included in the protected line section aswitching of the shunt reactor with the line in service will beinterpreted by the directional wave detectors as an internaIfault, if the switching current is higher than the set operatingvalues for the I'dependent mode" or the "neutral current controImode".

To prevent an unnecessary tripping from the "neutral currentcontroi mode", parts of the directional wave detector istemporarily disabled when the shunt reactor is closed in.

To prevent an unnecessary tripping from the "dependent mode"the directional wave detector operating value for current changecan be temporarily increased when the shunt reactor is closed in.

The setting for the temporary increase in operating va1ue forcurrent ch ange is made by means of the switches 51:1 and 51:2 inthe front of unit RXTEN 2H in position A 555.

increase incp. value 51:1 51:2

closed2x open

closed4x open

closed closed7x

Alternatively by closing 51:3, the "dependent mode" directionalwave detector can also be temporarily disabled when the shuntreactor is closed in.

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The time-setting for the temporary increase in operating valuefor current change is made by means of two thumbwheel-switches settable 1-99 x 10 ms at the front of unit RXKE l inposition A 1119. The multiples of 10 is set on the left of the twoswitches.

We normalIv recommend a setting of 500 ms which means athumbwheel position of 50.

..i~j

When the temporary increase in operating value is not usedswitches 51:1,51:2 and 51:3 shall be in the open position and theunit A 1119 shall be removed from the RALZA relay proper.

Note that the switches 51:1, 51:2 and 51:3 have no influence onthe "independent mode" directional wave detector nor anyinfluence on the zone 3 impedance measuring unit.

8COMPUTER FACILITIES

8 The RALZA relay settings can also be determined by computerprograms available at ASEA. When our computer facilities arerequired, for RALZA relay setting determination please contactus for further information.

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9DEFINITIONS

E'

represents the voltage to neutral existing prior to thefault in the far end of the line.

ZlA + ZOAZA

ZlB + lOBZB

ZlL + ZOLZL

Positive sequence source impedance behind linesection end A

ZlA

~ZlB positive sequence source impedance behind linesection end B

positive sequence line impedanceZlL

->ZOA zero sequence source impedance behind line sectionend A

zero sequence source impedance behind line sectionend B

ZOB

zero sequence line impedanceZOL

I' rated primary currentn

rated primary voltage to neutralU'n

In

rated secondary current

u rated secondary voltage-to-neutraln

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change in primary phase current

ch ange in primary voltage to neutral

61'LE

6U'LE

6I'LL

6U'LL

change in primary phase current for line-to-line fault

.

~ I'LLE

.

6U'LLE

61'3L

6U3L

change in primary phase current for three-phase fault

6rmin

r )

OU' min

86r maximum of chapgrs in primary phase curlrent =max(l~rLE I, l~rLLI ,1~rLLEI, ~I'3Lmax

I )

maximu~ of chargfS in prifIJao/ voltage jO nieutral = max. (16U'LE ' 6U'LL I ,16U'LLE ' 6U3LI )

..:?1[J 3

a= e

RF 619-002 E

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value of 61' referred to the secondary side

value of 6u' referred to the secondary side

6Umin

61 max

6Umax~

8u value of UI referred to the secondary side

~

U'min

I'max

U'max

8x current transformer ratio= rated primary current/rated secondary current

~

8C(

voltage transformer ratio= rated primary voltage/rated secondary voltage

6"max

The relationship between primary and secondary values is ob-tained by introduction of the instrument transformer ratios asshown below:

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10REFERENCE PUBLICATIaNS

RF 619-001 E Ultra High Speed Line Protection typ e RALZA

RF 619-003 E Commissioning Instruction for Ultra HighSpeed Line Protection type RALlA

i8

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