Testing Low Impedance

Testing Low Impedance

Testing Low Impedance

Bus Differential Relays

Bus Differential Relays

International ProTesT User Group Meeting

International ProTesT User Group Meeting

Vancouver, BC

Vancouver, BC

What You’ll Learn

What You’ll Learn

•

•

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si

si

cs

cs

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ff

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pr

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ec

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on

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in

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lo

lo

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w

im

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pe

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nc

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bus differential relays

Basics of Differential Protection

Basics of Differential Protection

•

•

B

B

a

a

s

s

e

e

d

d

o

o

n

n

K

K

i

i

r

r

c

c

h

h

o

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f

f

f

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’

’

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C

C

u

u

r

r

r

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e

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n

n

t

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L

L

a

a

w

w

(

(

K

K

C

C

L

L

)

)

 –

 – The The sum sum of of curcurrenrents ets ententerinring ag and nd exiexitinting ag a

node must equal 0

node must equal 0

 –

S

S

im

im

pl

pl

e B

e B

us

us

–

–

N

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or

or

m

m

a

a

l F

l F

lo

lo

w

w

52 52 5252

I

I

1

1

I

I

2

2

i

i

1

1

i

i

2

2

I1 = 1 I1 = 1

∠

∠

0°0° I2 = 1 I2 = 1

∠

∠

180°180° I1 + I2 = 0, per KCL I1 + I2 = 0, per KCL

Si

Si

mp

mp

le

le

Bu

Bu

s –

s –

Ex

Ex

te

te

rn

rn

al

al

Fa

Fa

ul

ul

t

t

52 52 5252

I

I

1

1

I

I

2

2

i

i

1

1

i

i

2

2

I1 = 3 I1 = 3

∠

∠

0°0° I2 = 3 I2 = 3

∠

∠

180°180° I1 + I2 = 0, per KCL I1 + I2 = 0, per KCL

Si

Si

mp

mp

le

le

Bu

Bu

s –

s –

In

In

te

te

rn

rn

al

al

Fa

Fa

ul

ul

t

t

I1 = 3 I1 = 3

∠

∠

0°0° I2 = 3 I2 = 3

∠

∠

0°0° I1 + I2 = 6, >0! I1 + I2 = 6, >0! • • II1 1 + + II2 2 = = IIDD, , tthhee differential current differential current 52 52 5252

I

I

1

1

I

I

2

2

i

i

1

1

i

i

2

2

Differential Protection

Differential Protection

•

•

Lo

Lo

ok

ok

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fo

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current

current

•

•

Re

Re

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p

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•

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a

a

l d

l d

i

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r

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n

n

t te

t te

c

c

h

h

n

n

i

i

q

q

u

u

e

e

s

s

Bus Fault Protection Requirements

Bus Fault Protection Requirements

•

•

H

H

i

i

g

g

h

h

s

s

p

p

e

e

e

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d

d

 –

 – Bus fBus fauaults alts are tyre typipicalcally hily highgh-m-magagninitutudede,,

damaging events

damaging events

•

•

S

S

e

e

c

c

u

u

r

r

e

e

 –

 – IncoIncorrerrect tct triprippinping a g a bus bus can can drodrop a p a sigsignifnificanicantt

part of the system

Bus Protection Techniques

Bus Protection Techniques

•

•

O

O

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r

r

c

c

u

u

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r

r

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•

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H

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m

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•

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L

L

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I

m

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p

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d

d

a

a

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D

D

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f

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n

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l

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Overcurrent Bus Protection

Overcurrent Bus Protection

• • UUssees s aan n oovveerrccuurrrreenntt element to detect ID element to detect ID • • IID D = = ii1 1 + + ii2 2 = = 00, , oor r  does it? does it?  –  – CT CT rerepplilicacatition on eerrrror or  – – CCT ST Saattuurraattiioonn 52 52 5252 I I11 II22 i i1 1 ii22 50 50 I I_DD

CT Replication Error 

CT Replication Error 

• • CCT T ppeerrffoorrmmaannccee rated ±10% (per  rated ±10% (per  ANSI) ANSI) • • II1 1 + + II2 2 = = 00 • • ii1 1 + + ii22

≠

≠

00 – – AAs s mmuucch h aas s 2200%% error  error  • • ++1100% % oon n ii11 • • --1100% % oon n ii22 • • 550 0 eelleemmeennt t mmuusst t bbee

set less sensitive!

set less sensitive!

52 52 5252 I I11 II22 i i1 1 ii22 50 50 I I_DD

CT Saturation

CT Saturation

• • SSaattuurraatteed d CCTT produces no current produces no current output output • • II1 1 + + II2 2 = = 00 • • ii1 1 + + ii22

≠

≠

00 – – ii2 2 = = 0 0 dduue e ttoo saturated CT saturated CT • • IID D = = ii11 • • 550 0 eelleemmeennt t mmuusst t bbee extremely extremely un-sensitive sensitive 52 52 5252 I I11 II22 i i1 1 ii22 50 50 I I_DD

High Impedance Differential

High Impedance Differential

I1 I1 I2 I2 I I_DD 52 52 52 52 87 87 + + V V - -R R • • AAccttuuaalllly y aann overvoltage relay overvoltage relay – – RReellaay y ooppeerraattees s oonn voltage across voltage across internal resistance internal resistance from ID from ID

High Impedance Differential

High Impedance Differential

• • PPlluusseess – – CClleevveer sr soolluuttiioon tn too CT saturation CT saturation • • HHiiggh h iimmppeeddaannccee forces differential forces differential current through current through other CTs other CTs • • VVoollttaaggee developed is less developed is less

than that of 

than that of 

internal fault internal fault – – RReelliiaabbllee • • MMiinnuusseess – – DDeeddiiccaatteed Cd CTTss – – MMaattcchheedd performance class performance class CTs CTs  –  – IdIdenentiticacal l CT CT rarattioios,s,

tapped at full ratio

Low Impedance Differential

Low Impedance Differential

• • MMaatthheemmaattiiccaalllly y ssuummss currents currents • • UUssees s rreessttrraaiinnt t ttoo maintain security maintain security • • NNo o ssppeecciiaal l CCTT requirements requirements – – DDiiffffeerreennt rt raattiioos,s, performance class performance class • • CCaan n pprroovviiddee waveform capture, waveform capture, and communications and communications 52 52 5252 I I11 II22 i1 i1 87 87 II_DD= i1 + i2= i1 + i2 i2 i2

Low Impedance Characteristic

Low Impedance Characteristic

S2 S2 S1 S1 ID ID IR IR Operate Operate w/ Restraint w/ Restraint IRs IRs IOmin IOmin High High Current Current Setting Setting Restrain Restrain Operate Operate w/o Restraint w/o Restraint 2 2 1 1 ii ii  ID  ID

=

=

+

+

2 2 1 1 ii ii  IR  IR

=

=

+

+

Lo

Lo

w

w

Im

Im

pe

pe

da

da

nc

nc

e

e

–

–

Lo

Lo

ad

ad

Fl

Fl

ow

ow

I1 = 1 I1 = 1

∠

∠

0°0° I2 = 1 I2 = 1

∠

∠

180°180° ID = |i1 + i2| = 0 ID = |i1 + i2| = 0 IR = |i1| + |i2| = 2 IR = |i1| + |i2| = 2 S2 S2 S1 S1 ID ID IR IR Operate Operate w/ Restraint w/ Restraint IRs IRs IOmin IOmin High High Current Current Setting Setting Restrain Restrain Operate Operate w/o Restraint w/o Restraint 52 52 5252 I I11 II22 i1 i1 87 87 I

I_DD= |i1 + i2|= |i1 + i2|

I

I_RR= |i1| + |i2|= |i1| + |i2|

i2

Lo

Lo

w

w

Im

Im

pe

pe

da

da

nc

nc

e

e

–

–

Ex

Ex

te

te

rn

rn

al

al

Fa

Fa

ul

ul

t

t

I1 = 3 I1 = 3

∠

∠

0°0° I2 = 3 I2 = 3

∠

∠

180°180° ID = |i1 + i2| = 0 ID = |i1 + i2| = 0 IR = |i1| + |i2| = 6 IR = |i1| + |i2| = 6 S2 S2 S1 S1 ID ID IR IR Operate Operate w/ Restraint w/ Restraint IRs IRs IOmin IOmin High High Current Current Setting Setting Restrain Restrain Operate Operate w/o Restraint w/o Restraint 52 52 5252 I I11 II22 i1 i1 87 87 I

I_DD= |i1 + i2|= |i1 + i2|

I

I_RR= |i1| + |i2|= |i1| + |i2|

i2

Lo

Lo

w Im

w Im

pe

pe

da

da

nc

nc

e –

e –

In

In

te

te

rn

rn

al F

al F

au

au

lt

lt

I1 = 3 I1 = 3

∠

∠

0°0° I2 = 3 I2 = 3

∠

∠

0°0° ID = |i1 + i2| = 6 ID = |i1 + i2| = 6 IR = |i1| + |i2| = 6 IR = |i1| + |i2| = 6 S2 S2 S1 S1 ID ID IR IR Operate Operate w/ Restraint w/ Restraint IRs IRs IOmin IOmin High High Current Current Setting Setting Restrain Restrain 52 52 5252 I I11 II22 i1 i1 87 87 I

I_DD= |i1 + i2|= |i1 + i2|

I

I_RR= |i1| + |i2|= |i1| + |i2|

i2

CT Error: Low Impedance

CT Error: Low Impedance

S2 S2 S1 S1 ID ID Operate Operate w/ Restraint w/ Restraint IOmin IOmin High High Current Current Setting Setting Restrain Restrain Load flow w/ Load flow w/ CT Error 

CT Error  _{External faultExternal fault} w/ CT Error  w/ CT Error  External fault w/ External fault w/ CT Saturations CT Saturations

Low Impedance Relays

Low Impedance Relays

•

•

N

N

x

x

t

t

P

P

h

h

a

a

s

s

e

e

B

B

-

-

P

P

R

R

O

O

•

•

G

G

E

E

B

B

-

-

3

3

0

0

•

•

S

S

E

E

L

L

4

4

8

8

7

7

B

B

•

•

Al

Al

l u

l u

se

se

si

si

mi

mi

la

la

r o

r o

pe

pe

ra

ra

ti

ti

ng

ng

ch

ch

ar

ar

ac

ac

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te

ri

ri

st

st

ic

ic

•

•

A

A

l

l

l

l

u

u

s

s

e

e

6

6

i

i

n

n

p

p

u

u

t

t

s

s

Low Impedance Applications

Low Impedance Applications

5 522 5522 5522 5 522 5522 5522 I I11 II22 II33 I I44 II55 II66 B-PRO  B-PRO  NxtPhase NxtPhase • • ((66) ) 33--pphhaasse e iinnppuuttss • • 8877B B ffuunnccttiioonn • • PPoossssiibblle e 2277, , 5599, , 8811 • • 5500//5511, , ppoossssiibblle e 6677

for each input

for each input

• • 5500BBF F ffoor r eeaacch h iinnppuutt • • PPoossssiibblle me muullttiippllee protection zones protection zones

Testing a Low Impedance Bus

Testing a Low Impedance Bus

Differential Relay

Differential Relay

4 Pieces of Knowledge

4 Pieces of Knowledge

•

•

Ho

Ho

w i

w i

s t

s t

h

h

e o

e o

p

p

er

er

a

a

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ti

ng

ng

ch

ch

a

a

ra

ra

ct

ct

e

e

ri

ri

st

st

i

i

c

c

defined?

defined?

– – CCuurrvve e eeqquuaattiioonnss

•

•

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Ho

w d

w d

oe

oe

s t

s t

h

h

e r

e r

el

el

ay

ay

ca

ca

l

l

cu

cu

l

l

at

at

e I

e I

D a

D a

n

n

d I

d I

R?

R?

•

•

Do

Do

es

es

th

th

e

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ch

ch

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ac

te

te

ri

ri

st

st

ic

ic

wo

wo

rk

rk

in

in

am

am

ps

ps

or 

or 

per unit

per unit

•

•

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R

e

e

l

l

a

a

y

y

s

s

e

e

t

t

t

t

i

i

n

n

g

g

s

s

GE B-30

GE B-30

•

•

I

I

D =

D =

|

|

i

i

1

1

+

+

i

i

2

2

+

+

i

i

3

3

+

+

i

i

4

4

+

+

i

i

5

5

+

+

i

i

6

6

|

|

•

•

I

I

R =

R =

m

m

a

a

x (

x (

I

I

1

1

, I

, I

2

2

, I

, I

3

3

, I

, I

4

4

, I

, I

5

5

, I

, I

6

6

)

)

•

•

Pe

Pe

r

r

u

u

ni

ni

t.

t.

Ba

Ba

se

se

i

i

s m

s m

ax

ax

i

i

m

m

um

um

p

p

ri

ri

m

m

ar

ar

y

y

current on an input

current on an input

SEL 487B

SEL 487B

•

•

I

I

D =

D =

|

|

i

i

1

1

+

+

i

i

2

2

+

+

i

i

3

3

+

+

i

i

4

4

+

+

i

i

5

5

+

+

i

i

6

6

|

|

•

•

I

I

R

R

=

=

|

|

i

i

1

1

|

|

+

+

…

…

|

|

i

i

6

6

|

|

•

•

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P

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r

r

u

u

n

n

i

i

t

t

.

.

B

B

a

a

s

s

e

e

i

i

s m

s m

a

a

x C

x C

T

T

r

r

a

a

t

t

i

i

o

o

NxtPhase B-PRO

NxtPhase B-PRO

•

•

I

I

D =

D =

|

|

i

i

1

1

+

+

i

i

2

2

+

+

i

i

3

3

+

+

i

i

4

4

+

+

i

i

5

5

+

+

i

i

6

6

|

|

•

•

I

I

R

R

=

=

(

(

|

|

i

i

1

1

|

|

+

+

…

…

+

+

|

|

i

i

6

6

|

|

)

)

/

/

2

2

•

•

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Pe

r u

r u

ni

ni

t b

t b

as

as

e o

e o

n B

n B

us

us

MV

MV

A /

A /

B

B

us

us

V

V

ol

ol

ta

ta

g

g

e

e

Testing Issues

Testing Issues

•

•

D

D

o

o

I

I

h

h

a

a

v

v

e

e

t

t

o

o

t

t

e

e

s

s

t

t

3

3

-

-

p

p

h

h

a

a

s

s

e

e

?

?

 –

 – No! No! DifDifferferentential ial proprotecttection ion is is singsingle-le-phaphasese

element element

•

•

Do

Do

I h

I h

av

av

e t

e t

o t

o t

es

es

t a

t a

ll

ll

6 i

6 i

np

np

ut

ut

s a

s a

t t

t t

he

he

sa

sa

me

me

time?

time?

 –

 – No! No! No No curcurrenrent it into nto an an inpinput ut is is 0 c0 currurrentent..

Differential characteristic still performs

Differential characteristic still performs

correctly.

B-PRO Characteristic

B-PRO Characteristic

S2 S2 S1 S1 ID ID IR IR Operate Operate w/ Restraint w/ Restraint IRs IRs IOmin IOmin High High Current Current Setting Setting Restrain Restrain Test Zone 1

Test Zone 1 _{Test Zone 3Test Zone 3}

(0, IOmin) (0, IOmin)                   min min ,, 1 1 100 100 min* min*  IO  IO S  S   IO  IO _{( ( ( ( )) ))}  IRs  IRs S  S   IRs  IRs,, 11₁₀₀₁₀₀** ( ( )) ( ( )) _                                        −− − −  I   I   High  High S  S   IRs  IRs S  S  S  S   I   I   High  High ,, 100 100 2 2 100 100 2 2 1 1 ( ( S S  )) IRIR  IO  IO ** 100 100 1 1 = = ( ( S S  ))  IR IR bb  IO  IO== ** ++ 100 100 2 2 ( ( ))  IRs  IRs S  S  S  S  b b 100 100 2 2 1 1−− = = 2 2 6 6 5 5 4 4 3 3 2 2 1 1 ii ii ii ii ii ii  IR  IR== ++ ++ ++ ++ ++ 6 6 5 5 4 4 3 3 2 2 1 1 ii ii ii ii ii ii  ID  ID== ++ ++ ++ ++ ++

Test Plan

Test Plan

•

•

T

T

e

e

s

s

t O

t O

b

b

v

v

i

i

o

o

u

u

s E

s E

x

x

t

t

e

e

r

r

n

n

a

a

l

l

F

F

a

a

u

u

l

l

t

t

 –  – VeVerirififies tes thahat tet test sst setetup up is cis cororrerectct

•

•

T

T

e

e

s

s

t O

t O

b

b

v

v

i

i

o

o

u

u

s I

s I

n

n

t

t

e

e

r

r

n

n

a

a

l

l

F

F

a

a

u

u

l

l

t

t

 –  – VeVerirify rfy relelay oay opeperaratiotion, tn, tesest set setutupp

•

•

Te

Te

st

st

ch

ch

a

a

ra

ra

ct

ct

er

er

is

is

ti

ti

c p

c p

e

e

rf

rf

o

o

rm

rm

an

an

ce

ce

Possible Test Setup

Possible Test Setup

Differential Relay Differential Relay Input 2 Input 2 A Phase A Phase Input 3 Input 3 A Phase A Phase Input 1 Input 1 A Phase A Phase Input 5 Input 5 A Phase A Phase Input 6 Input 6 A Phase A Phase Input 4 Input 4 A Phase A Phase Test Test Source 1 Source 1 0 0oo Test Test Source 2 Source 2 180 180oo

Possible Test Setup

Possible Test Setup

Divide all calculated test currents by 3!

Divide all calculated test currents by 3!

Differential Relay Differential Relay Input 2 Input 2 A Phase A Phase Input 3 Input 3 A Phase A Phase Input 1 Input 1 A Phase A Phase Input 5 Input 5 A Phase A Phase Input 6 Input 6 A Phase A Phase Input 4 Input 4 A Phase A Phase Test Test Source 1 Source 1 0 0oo Test Test Source 2 Source 2 180 180oo

Test Procedure

Test Procedure

•

•

C

C

o

o

l

l

l

l

e

e

c

c

t

t

B

B

-

-

P

P

R

R

O

O

s

s

e

e

t

t

t

t

i

i

n

n

g

g

s

s

•

•

Ca

Ca

l

l

c

c

u

u

l

l

a

a

t

t

e r

e r

e

e

l

l

a

a

y b

y b

a

a

s

s

e

e

cu

cu

r

r

r

r

e

e

n

n

t

t

•

•

De

De

te

te

rm

rm

in

in

e t

e t

es

es

t p

t p

oi

oi

nt

nt

s f

s f

ro

ro

m

m

di

di

ff

ff

er

er

en

en

ti

ti

al

al

characteristic

characteristic

•

•

Ca

Ca

l

l

c

c

u

u

l

l

a

a

t

t

e s

e s

e

e

co

co

n

n

d

d

a

a

r

r

y c

y c

u

u

r

r

r

r

e

e

n

n

t

t

s

s

•

•

T

T

e

e

s

s

t

t

Base Current

Base Current

•

•

Ba

Ba

se

se

Cu

Cu

rr

rr

e

e

nt

nt

i

i

s d

s d

e

e

fi

fi

ne

ne

d b

d b

y B

y B

us

us

MV

MV

A,

A,

Bus Voltage

Bus Voltage

 pri  pri  Base  Base  Base  Base

 A

 A

 I 

 I 

kV 

kV 

MVA

MVA

 Base

 Base

 I 

 I 

kV 

kV 

Voltage

Voltage

MVA

MVA

 Base

 Base

2000

2000

230

230

3

3

1000

1000

796

796

3

3

1000

1000

230

230

796

796

=

=

×

×

×

×

=

=

×

×

×

×

=

=

=

=

=

=

T

T

es

es

t

t

P

P

oi

oi

n

n

t

t

–

–

Lo

Lo

ad

ad

F

F

lo

lo

w

w

unit 

unit 

 per 

 per 

ii

ii

 IR

 IR

unit 

unit 

 per 

 per 

ii

ii

ii

ii

 ID

 ID

unit 

unit 

 per 

 per 

ii

unit 

unit 

 per 

 per 

ii

o o o o

1

1

2

2

1

1

1

1

2

2

2

2

1

1

0

0

2

2

1

1

2

2

1

1

180

180

1

1

2

2

0

0

1

1

1

1

=

=

+

+

=

=

+

+

=

=

=

=

−

−

=

=

+

+

=

=

∠

∠

=

=

∠

∠

=

=

T

T

es

es

t

t

P

P

oi

oi

n

n

t

t

–

–

Lo

Lo

ad

ad

F

F

lo

lo

w

w

( (

))

( (

))

oo  pri  pri o o  pri  pri  pri  pri  Base  Base  pri  pri  Base  Base  A  A  A  A Current  Current  Source Source Test  Test   A  A  A  A Current  Current  Source Source Test  Test  CTR CTR  Input   Input  CTR CTR  Input   Input   A  A  I   I  unit  unit   per   per   A  A  I   I  180 180 @ @ 33 33 .. 3 3 5 5 3000 3000 2000 2000 2 2 0 0 @ @ 5 5 5 5 2000 2000 2000 2000 1 1 5 5 :: 3000 3000 2 2 5 5 :: 2000 2000 1 1 2000 2000 2000 2000 1 1 1 1 2000 2000 sec sec sec sec

=

=

=

=

=

=

=

=

=

=

=

=

=

=

×

×

=

=

×

×

=

=

Operating Quantity Display

Operating Quantity Display

Bus

Bus DifferentiaDifferential l (87B) (87B) A A Phase Phase B B Phase Phase C C PhasePhase

--- --- ---

--- --- ---

---Operating

Operating Current, Current, IO IO (PU) (PU) 0.0 0.0 0.0 0.0 0.00.0

Restraint

Restraint Current, Current, IR IR (PU) (PU) 1.0 1.0 0.0 0.0 0.00.0

Note:

Te

Te

st

st

Po

Po

in

in

t –

t –

In

In

te

te

rn

rn

al

al

Fa

Fa

ul

ul

t

t

unit 

unit 

 per 

 per 

ii

ii

 IR

 IR

unit 

unit 

 per 

 per 

ii

ii

ii

ii

 ID

 ID

unit 

unit 

 per 

 per 

ii

unit 

unit 

 per 

 per 

ii

o o o o

1

1

2

2

1

1

1

1

2

2

2

2

1

1

2

2

2

2

1

1

2

2

1

1

0

0

1

1

2

2

0

0

1

1

1

1

=

=

+

+

=

=

+

+

=

=

=

=

+

+

=

=

+

+

=

=

∠

∠

=

=

∠

∠

=

=

Te

Te

st

st

Po

Po

in

in

t –

t –

In

In

te

te

rn

rn

al

al

Fa

Fa

ul

ul

t

t

( (

))

( (

))

oo  pri  pri o o  pri  pri  pri  pri  Base  Base  pri  pri  Base  Base  A  A  A  A Current  Current  Source Source Test  Test   A  A  A  A Current  Current  Source Source Test  Test  CTR CTR  Input   Input  CTR CTR  Input   Input   A  A  I   I  unit  unit   per   per   A  A  I   I  0 0 @ @ 33 33 .. 3 3 5 5 3000 3000 2000 2000 2 2 0 0 @ @ 5 5 5 5 2000 2000 2000 2000 1 1 5 5 :: 3000 3000 2 2 5 5 :: 2000 2000 1 1 2000 2000 2000 2000 1 1 1 1 2000 2000 sec sec sec sec

=

=

=

=

=

=

=

=

=

=

=

=

=

=

×

×

=

=

×

×

=

=

Operating Quantity Display

Operating Quantity Display

Bus

Bus Differential Differential (87B) (87B) A A Phase Phase B B Phase Phase C C PhasePhase

--- --- ---

--- --- ---

---Operating

Operating Current, Current, IO IO (PU) (PU) 2.0 2.0 0.0 0.0 0.00.0

Restraint

Restraint Current, Current, IR IR (PU) (PU) 1.0 1.0 0.0 0.0 0.00.0

Note:

Testing the characteristic

Testing the characteristic

•

•

Wh

Wh

y c

y c

an

an

’

’

t y

t y

o

o

u s

u s

ta

ta

rt

rt

wi

wi

th

th

a

a

n e

n e

xt

xt

e

e

rn

rn

a

a

l

l

fault, and vary 1 current until the

fault, and vary 1 current until the

relay

relay

operates?

operates?

•

You can…

You can…

• • IID D aannd d IIR R vvaarry y wwiitthh changing current changing current • • YYoou u mmuusst t ccaallccuullaattee to determine that i1 to determine that i1

and i2 from test

and i2 from test

source match source match characteristic characteristic • • MMuusst t vveerriiffy y tthhiis s iis s oonn characteristic! characteristic! IRs IRs IOmin IOmin

Initial test point Initial test point

Possible Trip Possible Trip

Points Points

A better way

A better way

•

• DDeetteerrmmiinne e IID D aannd d IIRR

for a specific test

for a specific test

point point • • CCaallccuullaatte e ii1 1 aannd d ii22 • • TTeesstt, , vvaarryyiinng g sslliigghhttllyy

around this region

around this region

IRs IRs

IOmin IOmin

Initial test point Initial test point

(IR, IO) (IR, IO)

Calculations

Calculations

( ( )) unit  unit   per   per   IO  IO  IB  IB  IB  IB unit  unit   per   per   IB  IB  IO  IO  IB  IB  IB  IB  IR  IR  IO  IO  IB  IB  IB  IB  IR  IR  IO  IO  IB  IB  IB  IB  IR  IR  IB  IB  IB  IB  IO  IO  IB  IB  IB  IB  IR  IR  IB  IB  IB  IB  IO  IO unit  unit   per   per   ID  ID  IR  IR at  at  Test  Test  example example Continuing  Continuing  in in out  out  in in in in out  out  in in in in out  out  in in out  out  in in out  out  in in out  out  in in 875 875 .. 0 0 25 25 .. 0 0 125 125 .. 1 1 125 125 .. 1 1 2 2 00 00 .. 1 1 2 2 25 25 .. 0 0 2 2 2 2 2 2 2 2 2 2 2 2 )) 25 25 .. 0 0 ,, 00 00 .. 1 1 (( ,, ... ... = = − − = = − − = = = = × × + + = = − − = = × × + + = = × × = = × × + + + + = = × × − − = = + + = = − − = = = =

Calculations

Calculations

( (

))

( (

))

oo  pri  pri  pri  pri o o  pri  pri  pri  pri out  out  in in  A  A CTR CTR  Apri  Apri ii  A  A  A  A unit  unit   per   per   A  A CTR CTR  Apri  Apri ii  A  A  A  A unit  unit   per   per  ii unit  unit   per   per   IB  IB ii unit  unit   per   per   IB  IB 180 180 @ @ 92 92 .. 2 2 5 5 3000 3000 1750 1750 1 1 1750 1750 2000 2000 875 875 .. 0 0 0 0 @ @ 625 625 .. 5 5 5 5 2000 2000 2250 2250 1 1 2250 2250 2000 2000 125 125 .. 1 1 2 2 875 875 .. 0 0 1 1 125 125 .. 1 1 sec sec sec sec = = = = = = × × = = = = = = × × = = = = = = = =

Operating Quantity Display

Operating Quantity Display

Bus

Bus Differential Differential (87B) (87B) A A Phase Phase B B Phase Phase C C PhasePhase --- --- --- --- --- --- ---Operating

Operating Current, Current, IO IO (PU) (PU) 0.3 0.3 0.0 0.0 0.00.0 Restraint

Restraint Current, Current, IR IR (PU) (PU) 1.0 1.0 0.0 0.0 0.00.0

Note:

Summary

Summary

•

•

Lo

Lo

w

w

im

im

pe

pe

da

da

nc

nc

e b

e b

us

us

di

di

ff

ff

er

er

en

en

ti

ti

al

al

is

is

ea

ea

sy

sy

to apply

to apply

•

•

T

T

e

e

s

s

t

t

i

i

n

n

g

g

– – 1 1 pphhaasse e ookkaayy – – 2 i2 innppuuts ts oonnlly oy okkaayy  –

 – MusMust t undunderserstantand d opeoperatrating ing chacharacracterteristiisticc

 –