1.

1 Procedure for Relay setting Calculation for MiCOM P442 Distance Relay

Data required

1. Positive sequence Line impedance = R1+jX1

2. Zero sequence Line impedance = R0+JX0
3. CT Ratio
4. PT Ratio
5. Protected Line Length in kms
6. Adjacent Shortest Line Length in kms
7. Adjacent Longest Line Length in kms
8. Voltage ratio of the transformer at the remote end if any
9. MVA of the transformer at the Remote end
10. % Impedance of the transformer at remote end
11. Maximum load on the feeder in Amperes

Calculation Procedure

The relay settings are in terms of impedance that is Z

Total Positive sequence impedance of protected line with reference to primary

ZPL = [ZPL (Ohms /km)*Protected Line Length (km)]

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT ratio/PT ratio)

Positive sequence impedance Angle = Tan-1(X1/R1)

Similarly the Impedance for Adjacent Shortest Line ZSL, Adjacent Remote Long

Line ZLL and second Adjacent Long Line Z2LL can be calculated.

Total Transformer Impedance ZT (At remote end)

If there is more than one Transformer, the resultant Impedance considering the Transformers are
in parallel is taken.

ZT = (%Transformer Impedance)*((KV) 2/ MVA)]

Zero sequence impedance Z0 = √R02+X02

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

Loadability:

The Limiting conditions for setting the distance relay reach to avoid encroachment into loads.
As per “Reliability Standard PRC-023”, The maximum impedance for the distance relay
characteristics along 30º on the impedance plane for 0.85 per unit rated voltage and the
maximum specified current for each condition.

2
The maximums Load w.r.t Secondary Zmax = 0.85*VL-L/ (√3*1.5*.IL)

Where IL corresponds to thermal limit of the conductor.

The Resistance reach corresponding to Zmax w.r.t Secondary

R = Zmax *COS (30)

The Reactance reach corresponding to Zmax w.r.t Secondary

X= Zmax *SIN (30)

The New impedance for Parallel line drawn parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts

The Resistance axis is Z new= X (at Zmax) /SIN (Line angle)

The New Resistance from Known Reactance Rnew = Znew* COS (Line angle)

Resistance reach of Relay Characteristics obtained from maximum Loadability condition

Resistive Reach R = (R correspond to Zmax – Rnew)

Zone Settings

Zone 1

Zone 1 = 80 % of Protection Line

Kz 1 Zero sequence compensation

Kz1 = (Z0-Z1/3*Z1)

Kz1 angle = angle of Kz1

As per manufacturer’s specification the maximum X/R ratio allowed is 10, hence considering
this limitation and the maximum loadability limit the minimum of the two is considered

Resistive reach

3
R1G= MIN of [(10 times of Zone1 Impedance) and 0.8*Resistive Reach at Max load)]

R1PH= MIN of [(10 times of Zone1 Impedance) and 0.6*Resistive Reach at Max load)]

Zone 2

Zone 2 = [MAX OF ((Protection line+ (0.5*Adjacent shortest line)) AND

(1.2*Protection line)]

tz2 = if [ZONE 2 > 80 % of Next shortest line then t=0.5sec else t=0.3 sec

Kz2 = (Z0-Z1/3*Z1)

Kz2 angle = angle of Kz2

R2G = Minimum [10 times of Zone 2 Impedance and 0.8*Resistive Reach at Max load]

R2PH = Minimum [10 times of Zone 2 Impedance and 0.6*Resistive Reach at Max load]

Zone 3

Zone3 = [MIN OF (1.2*Protection line + Adjacent Long line) & (Protection line + Adjacent
Long line +0.25* Adjacent Second Long Line) & (Protection line +Transformer
impedance))]

R3G-R4G = Minimum [(10 times of Zone 3 Reactance) and 0.8* Resistance at Maximum
load]

R3PH-R4PH = Minimum [(10 times of Zone 3 Reactance) and 0.6* Resistance at Maximum
load]

tz3 = 1 sec

Zone 4

Zone4 = 0.25 *Zone 1

tz4 = 1 sec

Power Swing:

Criteria 1:

∆f = 5Hz (As Per Manufacturer Specification)

∆R = 0.032*∆f*Maximum Loadability

= 0.032*5*Resistance at Maximum Load

∆X = 0.032*∆f*Maximum Loadability

= 0.032*5*Resistance at Maximum Load

4
Criteria 2:

∆R =∆X = 20% of Resistive reach of R3Ph

So a setting below the value can be retained of it.

5
Sample setting calculation for MiCOM P44X

Substation : 220kV GSS Ballabgargh

Line : Ballabgargh to Charki dadri

Relay Name : MiCOM P442

Data

Positive sequence Line impedance = 0.09705+j0.39314

Zero sequence Line impedance = 0.57146+j1.83241

CT Ratio = 1200A/1A

PT Ratio = 220kV/110V

Protected Line Length (Charki dadri) = 119.9 Km

Adjacent Shortest Line Length (two different conductor connected) (Bhiwani) = 26 (0.3) + 8.7
(0.4) Km

Adjacent Longest Line Length (Samayapur) = 116.10 (0.3) Km

Second Longest Line Length (Bhadshapur 1) = 24.10 (0.4) Km

Voltage ratio of the transformer = 220kV/132 kV

MVA of the transformer at the Remote end = 2*100 MVA

Impedance of the transformer = %12.344, 12.00

CT/PT ratio = 0.6

Calculation

Positive sequence impedance of Protected line ZPL = √R2+X2

= √0.097052+0.393412

ZPL = 0.4052 Ohms/Km

Total Positive sequence impedance of Protected line ZPL=

= [ZPL (Ohms /Km)*Protected Line Length (km)]

= [0.4049 * 119.9]

ZPL W.R.T Primary = 48.548 Ω

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT/PT ratio)

6
 = 48.548*(1200/1) / (220kV/110V)

ZPL = 29.129 Ω

Total Positive sequence impedance of the Adjacent Shortest line = (ZS1 + ZS2) * (CT/PT ratio)

Positive sequence impedance of Adjacent Shortest line 1 ZS1 = √R2+X2

= √0.097052+0.393412

= 0.4052* Line length

= 0.4052* 26

ZS1= 10.5352

Positive sequence impedance of Adjacent Shortest line 2 ZS2 = √R2+X2

= √0.07412+0.3832

= 0.390* Line length

= 0.390* 8.7

ZS2 = 3.393

Total Positive sequence impedance of the Adjacent Shortest line = (ZS1 + ZS2) * (CT/PT
ratio)

= (10.5352 + 3.393)* 0.6

ZSL W.R.T Secondary = 8.356 Ω

Total Positive sequence impedance of Adjacent Longest line ZLL=

= [ZLL (Ohms /Km)*Longest Line Length (km)]

= [0.4052 * 116]

ZLL W.R.T Primary = 47.00 Ω

ZLL W.R.T Secondary = ZLL W.R.T Primary * (CT/PT ratio)

= 47.00 * (1200/1) / (220kV/110V)

ZLL W.R.T Secondary = 28.201 Ω

Total Positive sequence impedance of Adjacent Second Longest line Z2LL=

= [ZLL (Ohms /Km)*Longest Line Length (km)]

= [0.4052 * 24.1]

7
Z2LL W.R.T Primary = 9.765Ω

Z2LL W.R.T Secondary = Z2LL W.R.T Primary * (CT/PT ratio)

= 9.765 * (1200/1) / (220kV/110V)

Z2LL W.R.T Secondary = 5.726 Ω

Total Transformer Impedance ZT (Remote):

If there is more than one Transformer, the resultant Impedance considering the Transformers are
in parallel is taken.

Considering Transformers are connected in parallel

Total Transformer Impedance ZT (Remote) = (% Transformer Impedance) *((kV) 2/MVA)]

Transformer Impedance Z1 = 0.12*(2202/100)

= 58.08 Ω

Transformer Impedance Z2 = 0.12344* (2202/100)

= 59.74496 Ω

Transformer Impedance W.R.T primary ZT = (1/((1/Z1)+(1/Z2)))

= 1/((1/58.08)+(1/59.74496))

ZT= 29.450 Ω

Transformer Impedance W.R.T Secondary ZT = 29.450 * 0.6

= 17.670 Ω

Load impedance for (as Per the NERC loadability)

Positive sequence impedance Angle =Tan-1(X/R)

Z1= Tan-1(0.39341/0.09705)

Line Angle = 76.14 Degree

The maximums Load w.r.t Secondary ZMAX primary = 0.85*VL-L/(√3*1.5*.IL)

ZMAX = 0.85* 220 /(√3*1.5*525)

[525 A is the maximum capacity of ACSR Goat conductor]

ZMAX = 137.1 Ω

The Resistance reach corresponding to Zmax w.r.t. Secondary

R = ZMAX *COS (30)

8
 = 137.1*0.8660

R = 118.733Ω

The Reactance reach corresponding to Zmax w.r.t Secondary

X = ZMAX *SIN (30)

= 137.1*0.5

X = 68.55 Ω

The New impedance for Parallel line Drawn Parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts the Resistance axis is

Znew = X (at Zmax) /SIN(76.14)

= 68.55/0.9708

Znew = 70.608 Ω

The New Resistance from Known Reactance Rnew = Znew* COS (76.14)

= 70.608 *0.239

R new = 16.922

Resistances reach of Relay Characteristics With respect to primary

= (R corresponds to Zmax – R new)

R = 118.733 – 16.922 ; R =101.811 Ω

With respect to secondary = 101.811*0.6

= 61.086 Ω

Zone Settings

Zone 1

Zone 1= 80 % of Protection Line

=0.8* 29.129

Zone 1 = 23.30 Ω

Kz1 = (Z0-Z1/3*Z1)

= (0.57146+j1.83241)-(0.09705+j0.39314) -/3(0.09705+j0.39314)

Zero sequence Line impedance = 1.247 ∟-4.378

Kz1 Magnitude = 1.247

9
Kz1 angle = - 4.378 degree

R1G = Minimum of [(10 times of Zone1 Impedance) and 0.8 *(Resistance at Max load)]

R1G = Min [(23.30) and (0.8*61.086)]

R1G =Min [233 and 48.869]

R1G = 48.869 Ω

R1PH = Minimum of [(10 times of Zone1 Impedance) and 0.6 *(Resistance at Max load)]

R1PH = Min [(10*23.30) and (0.6*61.086)]

R1PH =Min [233 and 36.65]

R1PH = 36.65 Ω

Zone 2

Zone 2 = Minimum of [[Maximum of ((Protection line+ (0.5*Adjacent shortest line))

AND (1.2*Protection line)] (Protection line+ (0.5*Transformer impedance)]

= Min of [[Max of [(29.129+ (0.5*8.356)) and (1.2*29.129] & (29.129+0.5*17.67)]

= Min of [[Max of 33.307 and 34.95] and 37.96]

Zone 2 = 34.95 Ω

tz2 = 0.35 sec

Kz1 = (Z0-Z1/3*Z1)

= (0.57146+j1.83241)-(0.09705+j0.39314) -/3(0.09705+j0.39314)

Zero sequence Line impedance = 1.247 ∟-4.378

Kz1 Magnitude = 1.247

Kz1 angle = - 4.378 degree

R2G = Min [10 times of Zone 2 Impedance and 0.8*Resistance at Max load]

= Min [10*34.95) and 0.8*61.086]

R2G = Min [349.5 and 48.869]

R2PH = Min [10 times of Zone 2 Impedance and 0.8*Resistance at Max load]

= Min [10*34.95) and 0.6*61.086]

R2PH = Min [349.5 and 36.65]

R2PH = 36.65 Ω

10
Zone 3

Zone3= [MIN OF (1.2(Protection line) +Adjacent Long line) & (Protection line Adjacent Long
line+25% Second Adjacent Long Line) & (Protection line+ Transformer impedance)]

= Min of (1.2*29.129+ 28.208) & (29.129+28.208+0.25*5.726) and (29.129+17.670)

= Min of (63.163 and 58.768 & 46.799)

Zone3 = 46.799 Ω

tz3 = 1 sec

Kz1 = (Z0-Z1/3*Z1)

= (0.57146+j1.83241)-(0.09705+j0.39314) -/3(0.09705+j0.39314)

Zero sequence Line impedance = 1.247 ∟-4.378

Kz1 Magnitude = 1.247

Kz1 angle = - 4.378 degree

R3G= Min [10 times of Zone 3 Impedance and 0.8*Resistance at Max load]

= Min [10*46.799 and 0.8*61.086]

= Min of [467.99 and 48.8688]

R3G = 48.869 Ω

R3PH= Min [10 times of Zone 3 Impedance and 0.6*Resistance at Max load]

= Min [10*46.799 and 0.6*61.086]

= Min of [467.99 and 36.65]

R3PH= 36.65 Ω

Zone 4

Zone4 = 0.25 *Zone1 ; Zone4 = 0.25* 23.30 Ω

Zone4 = 5.82 Ω

tz4 = 1 sec

11
Power Swing:

Criteria 1:

∆f = 5Hz (As Per Manufacturer Specification)

∆R = 0.032*∆f*Maximum Loadability

= 0.032*5*40.35

= 6.456 Ω

∆X = 0.032*∆f*Maximum Loadability

= 0.032*5*40.35

= 6.456 Ω

Criteria 2:

∆R =∆X = 20% of R3 Ph

= 0.2 * 36.69

= 7.33 Ω

So a setting below the value can be retained of it.

12
1.2 Procedure for Relay setting Calculation for MiCOM P433 Distance relay

Data required

1. Positive sequence Line impedance = R1+jX1

2. Zero sequence Line impedance = R0+JX0
3. CT Ratio
4. PT Ratio
5. Protected Line Length in kms
6. Adjacent Shortest Line Length in kms
7. Adjacent Longest Line Length in kms
8. Adjacent Second Longest Line Length in kms
9. Voltage ratio of the transformer at the remote end if any.
10. MVA of the transformer at the Remote end
11. % Impedance of the transformer at remote end
12. Maximum load on the feeder in Amperes

Calculation Procedure

The relay settings are in terms of impedance that is R and X

Total Positive sequence impedance of protected line with reference to primary
ZPL = [ZPL (Ohms /km)*Protected Line Length (km)]
ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT ratio/PT ratio)
Reactance of protected line = ZPL W.R.T Secondary *SIN(Line angle)
Resistance of protected line= ZPL W.R.T Secondary *COS (Line angle)
Positive sequence impedance Angle = Tan-1(X1/R1)
Similarly the Impedance for Adjacent Shortest Line ZSL, Adjacent Remote Long
Line ZLL and second Adjacent Long Line Z2LL can be calculated.
Total Transformer Impedance ZT(At Remote end) =
(% Transformer Impedance) *((KV) 2/MVA)]
Zero sequence impedance Z0 = √R0 +X02
2

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

Loadability:
The Limiting conditions for setting the distance relay reach to avoid encroachment into loads.
As per “Reliability Standard PRC-023”, the maximum impedance for the distance relay
characteristics along 30º on the impedance plane for 0.85 per unit rated voltage and the
maximum specified current for each condition.
The maximums Load w.r.t Secondary Zmax = 0.85*VL-L/ (√3*1.5*.IL)

Where IL corresponds to thermal limit of the conductor.

The Resistance reach corresponding to Zmax w.r.t Secondary

R = Zmax *COS (30)
The Reactance reach corresponding to Zmax w.r.t Secondary
X= Zmax *SIN (30)

13
The New impedance for Parallel line drawn parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts
the Resistance axis is Z new= X (at Zmax) /SIN (Line angle)

The New Resistance from Known Reactance Rnew = Znew* COS (Line angle)

Resistance reach of Relay Characteristics obtained from maximum loadability condition

Resistive Reach R = (R correspond to Zmax – Rnew)

Zone Settings

Zone 1
Zone 1 = 80 % of Protection Line
X1 = Z1 * SIN (Line Angle)
Kz 1 Zero sequence compensation
Kz1 = (Z0-Z1/3*Z1)
Kz1 angle = angle of Kz1
As per manufacturer’s specification the maximum X/R ratio allowed is 10, hence considering
this limitation and the maximum loadability limit the minimum of the two is considered
Resistive reach
R2= Zone2 impedance W.R.T Secondary *COS (Line angle)

R1 PH = Minimum of (8* Zone 1 Reactance and Resistance at maximum Load)

R1G = Minimum of (8* Zone 1 Reactance and Resistance at maximum Load)

Zone 2
Zone 2 = Min of [MAX OF ((Protection line+ (0.5*Adjacent shortest line)) and
(1.2*Protection line)] and (Protected line + 05* Transformer impedance)
X2 = Z2 * SIN (Line Angle)
tz2 = if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.3 sec
Kz2 = (Z0-Z1/3*Z1)
Kz2 angle = angle of Kz2

14
R2= Zone2 impedance W.R.T Secondary *COS (Line angle)
R2 PH = Minimum of (8* Zone 2 Reactance and Resistance at maximum Load)
R2 G = Minimum of (8* Zone 2 Reactance and Resistance at maximum Load)

Zone 3
Zone3 = [MIN OF (1.2*Protection line + Adjacent Long line) & (Protection line + Adjacent
Long line +0.25* Adjacent Second Long Line) & (Protection line +Transformer
impedance)]
R3= Zone3 impedance W.R.T Secondary *COS (Line angle)
R3 PH-R4PH = Minimum of (8* Zone 3 Reactance and Resistance at maximum Load)
R3 G-R4G =Minimum of (8* Zone 3 Reactance and Resistance at maximum Load)

tz3 = 1 sec

Zone 4
Zone4 = 0.25 *Zone 1
R4= Zone4 impedance W.R.T Secondary *COS (Line angle)
tz4 = 1 sec

Sample setting calculation for MiCOM P433

Substation : 220 kV Bhakra Power House

Line : 220 kV GSS Bhakra right to 220 kV GSS Mahilpur

Relay Name : Areva MiCOM P433

Data

Positive sequence Line impedance = 0.0797+j0.40651

15
Zero sequence Line impedance = 0.233+j1.329
CT Ratio = 1200A/1A
PT Ratio = 220kV/110V
Protected Line Length(Mahilpur) = 51.1 Km
Adjacent Shortest Line Length (Rehan) = 26.7 Km
Adjacent Longest Line Length (Bhakra Right) = 51.1 Km
Second Longest Line Length = 0 Km
Voltage ratio of the transformer = 220 kV/132 kV
Maximum load on the feeder = 795 A (for Zeebra)
CT/PT ratio = 0.6

Calculation

Positive sequence impedance of Protected line ZPL = √R2+X2

= √(0.07972+0.40652)

ZPL = 0.4142 Ohms/Km

Total Positive sequence impedance of Protected line ZPL=

= [ZPL (Ohms /Km)*Protected Line Length (km)]

= [0.4142 * 51.1]

ZPL W.R.T Primary = 21.167 Ω

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT/PT ratio)

= 21.167 * 0.6

ZPL = 12.70 Ω

Positive sequence impedance of Adjasent Shortest line ZSL = √R2+X2

= √(0.07972+0.40652)

ZSL = 0.4142 Ohms/Km

Total Positive sequence impedance Adjacent Shortest ZSL=

= [Z (Ohms /Km)*Protected Line Length (km)]

= [0.4142 * 26.7]

16
 ZSL W.R.T Primary = 11.06 Ω

ZSL W.R.T Secondary = ZSL W.R.T Primary * (CT/PT ratio)

= 11.06 *0.6

ZSL = 6.635 Ω

ZSL W.R.T Secondary = 6.635 Ω

Positive sequence impedance of Adjasent Longest line ZLL = √R2+X2

= √(0.07972+0.40652)

ZLL = 0.4142 Ohms/Km

Total Positive sequence impedance Adjacent Shortest ZLL=

= [Z (Ohms /Km)*Protected Line Length (km)]

= [0.4142 * 51.1]

ZLL W.R.T Primary = 21.167 Ω

ZLL W.R.T Secondary = ZLL W.R.T Primary * (CT/PT ratio)

= 21.167 * 0.6

ZLL W.R.T Secondary = 12.70 Ω

Total Positive sequence impedance of Adjacent Second Longest line Z2LL=

= [Z2LL (Ohms /Km)*Longest Line Length (km)]

= [0.4142 * 0]

Z2LL W.R.T Primary = 0Ω

Z2LL W.R.T Secondary = Z2LL W.R.T Primary * (CT/PT ratio)

= 0 * 0.6

Z2LL W.R.T Secondary = 0 Ω

Positive sequence impedance Angle =Tan-1(X/R)

Line Angle = Tan-1(0.4065/0.0797)

Line Angle = 78.91 Degree

17
The maximums Load w.r.t Secondary ZMAX primary = 0.85*VL-L/(√3*1.5*.IL)

ZMAX = 0.85* 220 /(√3*1.5*795)

[795 A is the maximum capacity of ACSR Zebra conductor]

ZMAX = 90.53 Ω

Corresponding Zmax secondary = Zmax * CT/PT Ratio = 90.53 * 0.6

= 54.32 Ω

The Resistance reach corresponding to Zmax w.r.t Secondary

R = ZMAX *COS (30)

= 54.32*0.8660

R = 47.044 Ω

The Reactance reach corresponding to Zmax w.r.t Secondary

X = ZMAX *SIN (30)

= 54.32*0.5

X = 27.16 Ω

The New impedance for Parallel line Drawn Parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts the Resistance axis is

Znew = X (at Zmax) /SIN(78.91)

= 27.16/ SIN (78.91)

Znew = 27.67 Ω

The New Resistance from Known Reactance Rnew = Znew* COS (78.91)

= 27.67*cos 78.91

R new = 5.322

Resistances reach of Relay Characteristics with respect to secondary

= (R corresponds to Zmax – R new)

R = 47.044 -5.322

R = 41.722 Ω

Zone Settings

Zone 1

18
Zone 1= 80 % of Protection Line

= 0.8 * 12.70

Zone 1 = 10.16 Ω

R1= Zone1 impedance W.R.T Secondary *COS (Line angle)

R1 (PH-PH) = Minimum of (8* Zone 1 Reactance and Resistance at maximum Load)
R1 (PH-E) =Minimum of (8* Zone 1 Reactance and Resistance at maximum Load)

X1PP, X1PG = 10.16* SIN (78.91)

X1PP, X1PG = 9.97 Ω

R1PP = Minimum of (8 *10.16 and 41.722)

R1PP = 41.722 Ω

R1PG = Minimum of (8*10.16 and 41.722)

R1PG= 41.722 Ω

Zone 2

Zone 2 = MIN OF [(Protected Line + 0.5*Transformer impedance at remote end) AND (MAX
OF (Protected line + (0.5*Adjacent shortest line) AND (1.2*Protected line))]

Since Transformer not available in Remote end.

= Max of [(16.02) and (15.24)]

= 16.02 Ω

Zone 2 = 16.02 Ω

tz4 = 0.35 sec

R2= Zone1 impedance W.R.T Secondary *COS (Line angle)

R2 (PH-PH) = Minimum of (8* Zone 2 Reactance and Resistance at maximum Load)

R2 (PH-E) =Minimum of (8* Zone 2 Reactance and Resistance at maximum Load)

X2PP, X2PG =16.02 * SIN (78.91)

19
 X2PP, X2PG = 15.72 Ω

R2PP = Minimum of (8* 16.02 and 41.722)

R2PP = 41.722 Ω

R2PG = Minimum of (8* 16.02 and 41.722)

R2PG= 41.722 Ω

Zone 3

Zone3= [MIN OF (1.2(Protected line) +Adjacent Long line) & (Protected line + Adjacent Long
line+25% Second Adjacent Long Line) & (Protected line +Transformer impedance at remote
end)]

Since Transformer not available in Remote end.

= Min of (15.24+ 12.7) & (12.70+12.70+0.25*0)

= Minimum of (27.94 and 25.40)

Zone3 = 25.40

tz3 = 1 sec

R3= Zone1 impedance W.R.T Secondary *COS (Line angle)

R3 (PH-PH) = Minimum of (8* Zone 3 Reactance and Resistance at maximum Load)

R3 (PH-E) =Minimum of (8* Zone 3 Reactance and Resistance at maximum Load)

X3PP, X3PG = 25.4 * SIN (78.91)

X3PP, X3PG = 24.925 Ω

R3PP = Minimum of (8*25.4 and 41.722)

R3PP = 41.722 Ω

R3PG = Minimum of (8*25.4 and 41.722)

R3PG= 41.722 Ω

Zone 4

20
Zone4 = 0.25 *Zone1 Impedance

Zone4 = 0.25*10.16 =2.54

X4 = 5.73 *SIN ( 78.91)

X4 = 2.49 Ω

tz4 = 1 sec

21
1.3Procedure for Relay Setting Calculation For REL670

Calculation

Protected line

Total Positive sequence Resistance of Protected line

R1 W.R.T Primary = [R1 (Ohms /Km)*Protected Line Length (km)]

Total Positive sequence Reactance of Protected line X1 =

X1 W.R.T Primary = [X1 (Ohms /Km)*Protected Line Length (km)]

Adjacent Shortest line

Total Positive sequence Resistance of Adjacent Short Line R =

R1 W.R.T Primary = [R1 (Ohms /Km)*Protected Line Length (km)]

Total Positive sequence Reactance of Adjacent Short LineX1 =

X1 W.R.T Primary= [X1 (Ohms /Km)*Protected Line Length (km)]

Adjacent Long Line

Positive sequence Resistance of Adjacent Longest Line Primary

R1 = [R1 (Ohms /Km)*Longest Line Length (km)]

Total Positive sequence Reactance of Adjacent Long LineX1 =

X1 W.R.T Primary = [X1 (Ohms /Km)* Adjacent Long Line Length (km)]

Transformer Impedance

Total Transformer Impedance ZT (At remote end)

If there is more than one Transformer, the resultant Impedance considering the Transformers are
in parallel is taken.

ZT = (%Transformer Impedance)*((KV) 2/ MVA)]

22
Loadability

Load impedance for (as Per the NERC Loadability)

The maximums Load w.r.t Secondary ZMAX = 0.85*VL-L / (√3*1.5*.IL)

Where ILcorresponds to thermal limit of the conductor.

The Resistance reach corresponding to Zmax w.r.t Secondary

R = ZMAX *COS (30)

The Reactance reach corresponding to Zmax w.r.t Secondary

X=ZMAX *SIN (30)

The New impedance for Parallel line Drawn Parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts the Resistance axis is Znew=X (at Zmax)
/SIN(Line Angle)

The New Resistance from Known Reactance Rnew= Znew* COS (Line Angle)

Resistance reach of Relay Characteristics

= (R corresponds to Zmax – Rnew)

Zero sequence impedance Z0 = √R2+X2

Zero sequence impedance Angle Z0

= Tan-1(X/R)

Protected line

Total Zero sequence Resistance of Protected line R =

Primary = [R0 (Ohms /Km)*Protected Line Length (km)]

Total Zero sequence Reactance of Protected line X0

W.R.T Primary = [ZPL (Ohms /Km)*Protected Line Length (km)]

23
Adjacent Short line

Total Zero sequence Resistance of Adjacent Short line R =

W.R.T Primary = [R0 (Ohms /Km)*Protected Line Length (km)]

Total Zero sequence Reactance of Adjacent Short line X0 =

X0 W.R.T Primary = [ZPL (Ohms /Km)* Adjacent Short line Length (km)]

Adjacent Long Line

Total Zero sequence Resistance of Adjacent Long line R

(Primary) = [R0 (Ohms /Km)* Adjacent Long Line Length (km)]

Zero sequence Reactance of Adjacent Long line X0 =

Total Zero sequence Reactance of Adjacent Long line X0 =

(Primary) = [ZPL (Ohms /Km)* Adjacent Long line Length (km)]

Positive sequence impedance Angle =Tan-1(X/R)

Zone Settings

Zone 1

Phase –Phase

X 1 = 80 % of (Protected Line)

R1 =80 % of (Protected Line)

RFPP = min [(3 times of Zone1 Reach) and 1.6*Zload min*(CosΘ-R1/X1*SinΘ)]

RFPE= min [4.5time Zone1 and [0.8*Zmin*[cos30 – ((2*R1PP+ROPE)/

(2*X1PP+XOPE)*sin30)]

Ref catalogue ABB REL 670 application manual page no 197,198 for the above condition
and the load encroachment function to be enabled for the second condition to prevail.

XO =80 % of (Protected Line Zero Sequence Reactance)

24
RO=80 % of (Protected Line Zero Sequence Resistance)

Zone 2

Phase –Phase

X 1 =Min of ([MAX OF ((Protected Line+ (0.5*Adjacent shortest line)) AND (1.2*Protected

Line)]), Protected Line + 0.5*Transformer Impedance at remote end)

R1 = MAX of ((Protected Line+ (0.5*Adjacent shortest line)) AND (1.2*Protected Line)))

RFPP = min [(3 times of Zone1 Reach) and 1.6*Zload min*(CosΘ-R1/X1*SinΘ)]

RFPE= min [4.5time Zone1 and [0.8*Zmin* [cos30 – ((2*R1PP+ROPE)/(2*X1PP+XOPE)

*sin30)]

X0 = Min of ([MAX OF ((Protected Line+ (0.5*Adjacent shortest line)) AND (1.2*Protected

Line)]),Protected Line+ 0.5*Transformer Impedance at remote end)

RO = MAX of ((Protected Line+ (0.5*Adjacent shortest line)) AND (1.2*Protected Line))

T2pp = if Zone2 > 80 % of the Next Shortest Line then t =0.6 sec else t=0.3 sec

t2pp= 0.35 sec

Zone 3

Phase –Phase

X1= MIN OF [(1.2*Protected Line Adjacent Long line)) & Protected Line Adjacent Long
line+0.25*second Long line & Protected Line+Transformer impedance at remote end]

R1= MIN of [(1.2*Protected Line+Adjacent Long line)) & Protected Line+Adjacent Long
line+0.25*second Long line]

RFPP = min [(3 times of Zone1 Reach) and 1.6*Zload min*(CosΘ-R1/X1*SinΘ)]

RFPE=min [4.5time Zone1 and [0.8*Zmin*[cos30 – ((2*R1PP+ROPE)/

(2*X1PP+XOPE)*sin30)]

X0 = [MIN OF (1.2*Protected Line+Adjacent Long line)) & Protected Line+Adjacent Long

line+0.25*second Long line & Protected Line+ Transformer impedance at remote end]

R0 = [MIN OF (1.2*Protected Line+Adjacent Long line)) & Protected Line+Adjacent Long

line+0.25*second Long line]

tz3 = 1 sec

25
Zone 4

Phase –Phase

X1 =0.25 *Zone 1 reach

RFPP = min [(3 times of Zone1 Reach) and 1.6*Zload min*(CosΘ-R1/X1*SinΘ)]

RFPE= min [4.5time Zone1 and [0.8*Zmin*[cos30 – ((2*R1PP+ROPE)/

(2*X1PP+XOPE)*sin30)]

XO= 0.25* Zone 1 reach

t4=1 sec

Sample setting Calculation for ABB REL 670 Distance Relay

Substation : 220kV Ganguwal

Line : 220kV Ganguwal to Bhakra

Relay Name : REL670

Protected Line

Positive sequence Line impedance = 0.0797+j0.4065

Zero sequence Line impedance = 0.233+j1.329
Adjacent Short Long line
Positive sequence Line impedance = 0.0797+j0.4065
Zero sequence Line impedance = 0.233+j1.329
Adjacent Longest Long line
Positive sequence Line impedance = 0.0797+j0.4065
Zero sequence Line impedance = 0.233+j1.329
Second Adjacent Longest Long line
Positive sequence Line impedance = 0.0797+j0.4065
Zero sequence Line impedance = 0.233+j1.329

CT Ratio = 1200A/1A

PT Ratio = 220kV/110V

ProtectedLineLength = 22.3 Km

Adjacent Shortest LineLength = 22.3 Km

AdjacentLongestLineLength = 86.4 Km

26
Second AdjacentLongestLine = 86.4 Km

Voltage ratio of the transformer = nil

MVA of the transformer at the Remote end = NA

Maximum load on the feeder = 795 A

CT/PT ratio = 0.6

Calculation

Protected line

Positive sequence Impedance of Protected line ZPL = (0.0797+j0.4065)Ohms/Km

Total Positive sequence Impedance of Protected line R =

= [Z1 (Ohms /Km)*Protected Line Length (km)]

= [22.3* (0.0797+j0.4065)]

ZPL W.R.T Primary = 1.77731+j9.06495

R1p-p = 1.77731 Ω =R1p-e

X1p-p = 9.06495 Ω =X1p-e

Zero sequence Impedance of Protected line ZPL = 0.233+j1.329Ohms/Km

Total Zero sequence Impedance of Protected line R =

= [Z1 (Ohms /Km)*Protected Line Length (km)]

= [22.3*(0.233+j1.329)]

ZPL W.R.T Primary = 5.1959+j29.63

ROp-e =5.1959Ω

XOp-e =29.63Ω

Adjacent Shortest line

Positive sequence Impedance of Adjacent Short line ZSL

Total Positive sequence impedance of Adjacent Short Line =

27
Total Positive sequence Impedance of Protected line R =

= [Z1 (Ohms /Km)*Protected Line Length (km)]

= [22.3* (0.0797+j0.4065)]

ZPL W.R.T Primary = 1.77731+j9.06495

ZSLW.R.T Primary = [22.3* (0.0797+j0.4065)]

= 1.77731+j9.06495

R1 W.R.T Primary = 1.77731 Ω

X1 W.R.T Primary = 9.06495 Ω

50% of Positive sequence Impedance of Adjacent Short line

50% ZSL = 0.8886+j4.5324 Ohms/Km

Zero sequence Impedance of Adjacent Short line ZSL

= [22.3*(0.233+j1.329)]Ohms/Km

=5.1959+j29.63

50% of Zero sequence Impedance of Adjacent Short line

ZSL W.R.T Primary = 50% (5.1959+j29.63)

R1 W.R.T Primary = 2.59795Ω

X1 W.R.T Primary = 14.815Ω

Adjacent Long Line

Positive sequence Impedance of Adjacent Longest Line =0.0797+j0.4065Ohms /Km

Total Positive sequence Impedance of Adjacent Longest Line

Z1 = [Z1 (Ohms /Km)*Longest Line Length (km)]

= [0.0797+j0.4065] *86.4]

28
Z1 W.R.T Primary = 6.88+j35.12

R1 W.R.T Primary = 6.88 Ω

X1 W.R.T Primary = 35.12 Ω

Zero sequence Impedance of Adjacent Longest Line=0.233+j1.329Ohms /Km

Z0 = [Z0 (Ohms /Km)*Longest Line Length (km)]

= [0.233+j1.329] * 86.4]

Z0 W.R.T Primary = 20.1312+j114.8256

R0 W.R.T Primary = 20.1312 Ω

X0 W.R.T Primary = 114.8256 Ω

Adjacent Second Long Line

Positive sequence Impedance of Adjacent Longest Line = 0.0797+j0.4065Ohms /Km

25 % of Z2LL = 0.25* [Z1 (Ohms /Km)*Longest Line Length (km)]

=0.25*[0.0797+j0.4065]*86.4)]
=0.25*[6.88+j35.12]

25% of Z2LL Positive sequence W.R.T Primary = (01.72+j8.78)

R1 W.R.T Primary =1.72Ω

X1 W.R.T Primary = 8.78 Ω

Zero sequence Impedance of Adjacent Longest Line= 0.48787+j1.92051Ohms /Km

25 % of Z2LL = [Z0 (Ohms /Km)*Longest Line Length (km)]

Total length = 0.25*(0.233+j1.329)*86.4

25% Z2LL Zero sequence W.R.T Primary = (5.0328+j28.7064)

R1 W.R.T Primary = 5.0328 Ω

X1 W.R.T Primary = 28.7064 Ω

Loadability

29
Load impedance for (as Per the NERC Loadability)

The maximums Load w.r.t Primary ZMAX = 0.85*VL-L/ (√3*1.5*.IL)

ZMAX = 0.85* 220000/√3*1.5*795)

ZMAX= 90.536 Ω

The Resistance reach corresponding to Zmax w.r.t Primary

R = ZMAX *COS (30)

=90.536*0.8660

R = 78.41 Ω

The Reactance reach corresponding to Zmax w.r.t Primary

X=ZMAX *SIN (30)

X = 45. 25 Ω

The New impedance for Parallel line Drawn Parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts the Resistance axis is Znew=X (at Zmax)
/SIN(78.85)

= 45.25 /0.9811

Znew = 46.12 Ω

The New Resistance from Known Reactance Rnew= Znew* COS (78.9)

= 46.12*0.1925

Rnew = 8.879 Ω

Resistance reach of Relay Characteristics

= (R corresponds to Zmax – Rnew)

R = 78.41 – 8.879

R = 69.531 Ω

Resistance reach of Relay Characteristics w r t Primary = 69.531 Ω

30
Positive sequence impedance Angle =Tan-1(X/R)

= Tan-1(X/R)

= Tan-1(0.4065/ 0.0797)

Z1 angle = 78.9 Degree

Zero sequence impedance Angle Z0

= Tan-1(1.329/0.233)

Z0 angle = 80.05 Degree

Zone Settings

Zone 1

Total length =22.3km

Zone 1 Length = 0.8 * Total length

= 0.8*22.3

= 17.84km

Phase –Phase

Zone 1= 80 % of (Protected Line)

= [0.8*(1.77731+9.06495j)]

= 1.421+ j7.2519

X 1PP = 7.2519 Ω

R1PP= 1.421 Ω

RFPP = min [(3 times of Zone1 Reach) and 1.6*Zloadmin*{cosΘ-R1/X1*SinΘ)]

= min of (3*7.25) and 1.6*90.536*{cos30 -1.421/7.2519*sin 30}

RFPP =21.76Ω

Phase –Earth

X 1PP= X1PE= 7.2519 Ω

31
R1PP = R1PE= 1.421 Ω

Zone1 Zero sequence Impedance = 80 % of Protected line Zero sequence impedance

= [0.8*(5.1959+j29.63)]

= 4.15672+j23.704

ROPE = 4.15672 Ω

XOPE = 23.704 Ω

RFPE = min [(4.5 times of Zone1 Reach) and 0.8* Zload max (cos ¢-((2*R1PE + ROPE / 2*
X1PE + XOPE) * sin¢)])]

= min (4.5*7.25) and [0.8*Zload-cos¢-(2*R1PP+ROPE) / (2*X1PP+XOPE)*sin¢

= min (4.5*7.25) and [0.8*90.536*[cos30–2*1.421 +4.156)/(2*7.2519+23.704)*sin30)]

= 32.625

RFPE = 32.625 Ω

Zone 2

Phase –Phase

ZONE2 = [MAX OF ((Protected Line+ (0.5*Adjacent shortest line)), AND (1.2*Protected

Line)] and MIN OF [Protected Line +0.5*Transformer impedance at remote end]

1.2*Protected Line = 1.2*(1.77731+j9.06495)

= (2.132+j10.877)

Protected Line + (0.5*Adjacent shortest line) = (1.77731+j9.06495) + 0.5*(1.77731+j9.06495)

= (2.665965+ j13.597)

X 1PP = 13.597Ω

R1PP = 2.665965Ω

RFPP = min [3 times of X1PP and 1.6*Zloadmin*{cosΘ-R1/X1*SinΘ)]

= (3*13.597) and 1.6* 90.536*{cos30-2.66/13.597*sin30}

32
RFPP = 40.791 Ω

T2pp= if Zone2 > 80 % of the Next Shortest Line then t =0.6 sec else t=0.3 sec

t2pp= 0.350 sec

Phase –Earth

X 1PE = 13.597Ω

R1PE = 2.665965Ω

Zone 2

Zero Sequence = Min of [MAX OF ((Protected Line+ (0.5*Adjacent shortest line)) AND1.2
*Protected Line])

1.2*Protected Line = 1.2 * (5.1959+j29.63)

= 6.236+ j35.55

Protected Line+ (0.5*Adjacent shortest line) = (5.1959+j29.63)+ 0.5*(5.1959+j29.63)

= 7.795 + j44.445

XOPE = 44.445 Ω

ROPE = 7.795 Ω

RFPE = min (4.5*44.445) and [0.8*Zload-cos¢-(2*R1PP+ROPE)/ (2*X1PP+XOPE)*sin¢

= min (200) and 0.8* 90.536- cos(30)-(2*2.66+7.795)/ (2*13.597+44.445)*sin(30)

= 200 and 56.095

RFPE = 56.095 Ω

Zone 3

Phase –Phase

Zone 3= [MIN OF (1.2*Protected Line + Adjacent Long line)), Protected Line +Adjacent Long
line+0.25 second long line)]

1.2*Protected Line+ Adjacent Long line =1.2 *(1.77731+j9.06495) + (6.88+j35.12)

33
= 9.012772+ j45.99

Protected Line +Adjacent Long line+0.25 second long line

= (1.77731+j9.06495) + (6.88+j35.12) + 0.25* (6.88+j35.12)

= 10.377 +j52.964

Zone 3 impedance =9.012772+ j45.99

X1PP = 45.99Ω

R1PP= 9.012772Ω

RFPP= min [3 times of Zone Reach and 1.6*Zloadmin*{cosΘ-R1/X1*SinΘ}]

=min [3 * 45.90 and (1.6*90.536*0.753)]

= 109.077Ω

X1PE = 45.99Ω

R1PE= 9.012Ω

Phase –Earth

Zone 3= [MIN OF (1.2*Protected Line +Adjacent Long line)), Protected Line +Adjacent Long
line+0.25 second long line)]

1.2*Protected Line +Adjacent Long line = 1.2*(5.1959+j29.63)+ (20.1312+j114.8256)

= 26.366+j150.38

Protected Line +Adjacent Long line+0.25 second long line

= (5.1959+j29.63)+(20.1312+j114.8256)+0.25*(20.1312+j114.8256)

= 30.3599+j173.162

XOPE = 150.38Ω

ROPE = 26.366Ω

RFPE = min (4.5*150.38) and [0.8*Zload-cos¢-(2*R1PP+ROPE)/ (2*X1PP+XOPE)*sin¢

34
 = min 676.71& (0.8*90.536 [cos(30)-(2*9.012+26.366)/(2*45.99+150.38)*sin(30)]

RFPE = 56.09Ω

tz3 =1 sec

Zone 4

Phase –Phase

Zone4 = 0.25 *Zone 1 impedance = 0.25*(1.421+ j7.2519)

X1PP= 1.812Ω

R1PP= 0.355 Ω

RFPP = min [3 times of Zone Reach and 1.6*Zloadmin*{cosΘ-R1/X1*SinΘ}]

= 3 *1.812and 1.6 *90.536*{cos30-0.355/1.812sin30}

RFPP = 5.436 Ω

Phase –Earth

X1PE= 1.812Ω

R1PE= 0.355Ω

RFPE = min [4.5 times of Zone Reach and [0.8*Zload-cos¢-(2*R1PP+ROPE)/

(2*X1PP+XOPE)*sin¢]

= 4.5*1.812 and 0.8*90.536*0.7744

RFPE = 8.154Ω

Zone4 Zero sequence = 0.25*zone 1 zero sequence= (5.1959+j29.63)*0.25

XOPE =7.4075Ω

ROPE = 1.298Ω

tz4=1 sec

Note: If Arc and Tower footing resistance are known then it is possible to set the correct value
of RFPP and RFPE by taking the consideration as;

35
 Criteria 1= Arc resistance

Criteria 2=Arc resistance+Tower footing resistance

Then the equation can be modified as given below;

RFPP= Min(3 times of Zone Reach and 1.6*Zloadmin*{cosΘ-R1/X1*SinΘ}],2*criteria1)

RFPE=min [4.5 times of Zone Reach and [0.8*Zload-cos¢-(2*R1PP+ROPE)/

(2*X1PP+XOPE)*sin¢, 2*criteria 2]

1.4 Procedure for Relay setting Calculation for SIEMENS SIPROTECH 7SA52X/7SA61X

Data required

1. Positive sequence Line impedance = R1+jX1

2. Zero sequence Line impedance = R0+JX0
3. CT Ratio
4. PT Ratio

36
 5. Protected Line Length in kms
6. Adjacent Shortest Line Length in kms
7. Adjacent Longest Line Length in kms
8. Adjacent Second Longest Line Length in kms
9. Voltage ratio of the transformer at the remote end if any.
10. MVA of the transformer at the Remote end
11. % Impedance of the transformer at remote end
12. Maximum load on the feeder in Amperes

Calculation Procedure
The relay settings are in terms of impedance that is R and X
Total Positive sequence impedance of protected line with reference to primary
ZPL = [ZPL (Ohms /km)*Protected Line Length (km)]
ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT ratio/PT ratio)
Reactance of protected line = ZPL W.R.T Secondary *SIN(Line angle)
Resistance of protected line= ZPL W.R.T Secondary *COS (Line angle)
Positive sequence impedance Angle = Tan-1(X1/R1)
Similarly the Impedance for Adjacent Shortest Line ZSL, Adjacent Remote Long
Line ZLL and second Adjacent Long Line Z2LL can be calculated.

Total Transformer Impedance ZT (At remote end)

If there is more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

ZT = (%Transformer Impedance)*((KV) 2/ MVA)]

Zero sequence impedance Z0 = √R02+X02

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

Loadability:
The Limiting conditions for setting the distance relay reach to avoid encroachment into
loads. As per “Reliability Standard PRC-023”, The maximum impedance for the distance
relay characteristics along 30º on the impedance plane for 0.85 per unit rated voltage and
the maximum specified current for each condition.
The maximums Load w.r.t Secondary Zmax = 0.85*VL-L/ (√3*1.5*.IL)

Where IL corresponds to thermal limit of the conductor.

The Resistance reach corresponding to Zmax w.r.t Secondary

R = Zmax *COS (30)
The Reactance reach corresponding to Zmax w.r.t Secondary
X= Zmax *SIN (30)
The New impedance for Parallel line drawn parallel to the Line impedance passing
through Zmax to the point at which the parallel line cuts
the Resistance axis is Z new= X (at Zmax) /SIN (Line angle)

The New Resistance from Known Reactance Rnew = Znew* COS (Line angle)

37
Resistance reach of Relay Characteristics obtained from maximum loadability condition

Resistive Reach R = (R correspond to Zmax – Rnew)

Zone Settings

Zone 1
Zone 1 = 80 % of Protection Line
R1= Zone1 impedance W.R.T Secondary *COS (Line angle)

Zone 2
Zone 2 = Min of [MAX OF ((Protection line+ (0.5*Adjacent shortest line)) AND
(1.2*Protection line)] & (Protection line+ 0.5*Transformer Impedance at remote end)
tz2 = if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.35 sec

R2= Zone2 impedance W.R.T Secondary *COS (Line angle)

R2 (PH-PH) = R2 + (Arc Resistance / 2)
R2 (PH-E) = R2 + Arc Resistance + Tower Footing Resistance

Zone 3
Zone3 = [MIN OF (1.2*Protection line + Adjacent Long line) & (Protection line +
Adjacent Long line +0.25* Adjacent Second Long Line) & (Protection line +Transformer
impedance))]
R3= Zone3 impedance W.R.T Secondary *COS (Line angle)
R3 (PH-PH) = R3 + (Arc Resistance / 2)
R3 (PH-E) = R3 + Arc Resistance + Tower Footing Resistance
tz3 = 1 sec

Zone 4
Zone4 = 0.25 *Zone 1
R4= Zone4 impedance W.R.T Secondary *COS (Line angle)

38
 R4 (PH-PH) = R4 + (Arc Resistance / 2)
R4 (PH-E) = R4 + Arc Resistance + Tower Footing Resistance
tz4 = 1sec

Power Swing Blocking:

As per manufactures specification power swing zone has a minimum distance

Zdiff of 5 Ω (at inom = 1 A) or 1 Ω(at inom = 5 A)

39
Sample setting calculation for SIPROTECH 7SA522

Substation : Charkhi Dadri

Line : Charkhi dadri to Khethri I

Relay Name : SIEMENS SIPROTECH 7SA522

Data

Protected Line

Positive sequence Line impedance = 0.0797+j0.4065

Zero sequence Line impedance = 0.233+j1.329
Adjacent Short Long line
Positive sequence Line impedance = 0.0797+j0.4065
Zero sequence Line impedance = 0.233+j1.329
Adjacent Longest Long line
Positive sequence Line impedance = 0.0797+j0.4065
Zero sequence Line impedance = 0.233+j1.329
Second Adjacent Longest Long line
Positive sequence Line impedance = 0.0797+j0.4065
Zero sequence Line impedance = 0.233+j1.329
CT Ratio = 600A/1A
PT Ratio = 220kV/110V
Protected Line Length = 71.61 Km
Adjacent Shortest Line Length (Khethri) = 34.5 Km
Adjacent Longest Line Length (Heerapura) = 144 Km
Second Longest Line Length (Heerapura -Khethri) = 139 Km
Voltage ratio of the transformer = 220kV/132kV
MVA of the transformer at the Remote end = 3*100 MVA and 1*150 MVA
Impedance of the transformer = %12,08, % 10.35, %9.65, %10.98
Maximum load on the feeder = 795 A
CT/PT ratio = 0.3

Calculation

Positive sequence impedance of Protected line ZPL = √R2+X2

= √(0.07972+0.40652)

ZPL = 0.414 Ohms/Km

40
Total Positive sequence impedance of Protected line ZPL=

= [ZPL (Ohms /Km)*Protected Line Length (km)]

= [0.414 * 71.61]

ZPL W.R.T Primary = 29.66 Ω

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT/PT ratio)

= 29.66 *0.3

ZPL = 8.90 Ω

Positive sequence impedance of Adjacent Shortest line ZSL= √R2+X2

= √(0.07972+0.40652)

ZSL = 0.414 Ohms/Km

Total Positive sequence impedance Adjacent Shortest ZSL=

= [Z (Ohms /Km)*Adjacent short Line Length (km)]

= [0.414 * 34.5]

ZSL W.R.T Primary = 14.29 Ω

ZSL W.R.T Secondary = ZSL W.R.T Primary * (CT/PT ratio)

= 14.29 * 0.3

ZSL W.R.T Secondary = 4.29 Ω

Positive sequence impedance of Adjacent Longest line ZLL = √R2+X2

= √(0.07972+0.40652)

ZLL = 0.414 Ohms/Km

Total Positive sequence impedance of Adjacent Longest line ZLL=

= [ZLL (Ohms /Km)*Longest Line Length (km)]

= [0.414 * 144]

ZLL W.R.T Primary = 59.65 Ω

41
ZLL W.R.T Secondary = ZLL W.R.T Primary * (CT/PT ratio)

= 59.65 * 0.3

ZLL W.R.T Secondary = 17.90 Ω

Positive sequence impedance of Adjacent Second Longest line ZS = √R2+X2

= √(0.07972+0.40652)

Z2LL = 0.414 Ohms/Km

Total Positive sequence impedance of Adjacent Second Longest line Z2LL=

= [Z2LL (Ohms /Km)*Longest Line Length (km)]

= [0.414 * 144]

Z2LL W.R.T Primary = 57.58 Ω

Z2LL W.R.T Secondary = Z2LL W.R.T Primary * (CT/PT ratio)

= 57.58 * 0.3

Z2LL W.R.T Secondary = 17.27 Ω

Total Transformer Impedance ZT (Remote):

If there are more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

Considering Transformers are connected in parallel

Total Transformer Impedance ZT (Remote) = (% Transformer Impedance) *((kV) 2/MVA)]

Transformer 1 Impedance Z1 = 0.0965*(2202/100)

= 46.706 Ω

Transformer 1 Impedance Z2 = 0.1208*(2202/100)

= 58.4672 Ω

Transformer 1 Impedance Z3 = 0.1035*(2202/100)

= 50.094 Ω

Transformer 1 Impedance Z4 = 0.1098*(2202/150)

42
 = 35.4288 Ω

Total Transformer Impedance W.R.T primary ZT = 1/ ((1/Z1) + (1/Z2) + (1/Z3) + (1/Z4))

ZT = 1/ ((1/46.706)+(1/58.467)+(1/50.094)+(1/35.4288))

ZT = 11.5337 Ω

Load impedance for (as Per the NERC loadability)

Positive sequence impedance Angle =Tan-1(X/R)

Z1= Tan-1(0.415/.0741)

Line Angle = 78.91 Degree

The maximums Load w.r.t Secondary ZMAX primary = 0.85*VL-L/(√3*1.5*.IL)

ZMAX = 0.85* 220 / (√3*1.5*795)

[795 A is the maximum capacity of ACSR Zebra conductor]

ZMAX = 90.53 Ω

Corresponding Zmax secondary = Zmax * CT/PT Ratio = 90.53 * 0.3 = 27.159 Ω

The Resistance reach corresponding to Zmax w.r.t Secondary

R = ZMAX *COS (30)

= 27.159 *0.8660

R = 23.519 Ω

The Reactance reach corresponding to Zmax w.r.t Secondary

X = ZMAX *SIN (30)

= 27.159 *0.5

X = 13.579 Ω

The New impedance for Parallel line Drawn Parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts the Resistance axis is

Znew = X (at Zmax) /SIN(78.91)

= 13.579/ SIN(78.91)

Znew = 13.83 Ω

The New Resistance from Known Reactance Rnew = Znew* COS (78.91)

= 13.83*cos 78.91

43
 R new = 2.66

Resistances reach of Relay Characteristics

= (R corresponds to Zmax – R new)

R = 23.519 -2.66

R = 20.86 Ω

Tower Footing Resistance assuming = 10 Ω in secondary

Arc Resistance(Ph-Ph) assuming = 10 Ω in secondary

Zone Settings

Zone 1

Zone 1= 80 % of Protection Line

= 0.8* 8.90

Zone 1 = 7.12 Ω

R1= Zone1 impedance W.R.T Secondary *COS (Line angle)

R1 (PH-PH) = R1 + (Arc Resistance / 2)
R1 (PH-E) = R1 + Arc Resistance + Tower Footing Resistance

R1 = 7.12* COS (78.91)

R1 = 1.37 Ω

R1(PH-PH) = 1.37 +(10/2)

R1(PH-PH) = 6.37Ω

R1(PH-PE) = 1.37+10+10

R1(PH-PE)= 21.37 Ω

Zone 2

44
Zone 2 = MIN OF [MAX OF (Protected line + (0.5*Adjacent shortest line) and (1.2*Protected
line)] and (Protected Line + 0.5*Transformer impedance at remote end)

= Min Of [Max of [(8.90+ (0.5*4.29) and (1.2*8.90)] and (8.90+0.5*3.46)

= Min Of [Max of [11.045 and 10.68] and 10.63

= 11.045 and 10.68

Zone 2 = 10.63 Ω

tz2 = 0.35 sec

R2= Zone 2 impedance W.R.T Secondary *COS(Line angle)

R2 (PH-PH) = R2 + (Arc Resistance / 2)
R2 (PH-E) = R2 + Arc Resistance + Tower Footing Resistance

R2 = 10.63 * COS (78.91)

R2 = 2.044 Ω

R2(PH-PH) = 2.044 +(10/2)

R2(PH-PH) = 7.05 Ω

R2(PH-PE) = +10+10

R2(PH-PE)= 22.05 Ω

Zone 3

Zone3= MIN OF [(1.2(Protected line) +Adjacent Long line) & (Protected line + Adjacent Long
line+25% Second Adjacent Long Line) & (Protected line +Transformer impedance)]

= Min of (1.2*8.90+ 17.90) & (8.90+17.90+0.25*17.27) and (8.90+3.46)

=Min of (28.58 and 31.117 & 12.36)

Zone3 = 12.36 Ω

tz3 = 1 sec

R3= Zone 3 impedance W.R.T Secondary *COS(Line angle)

R3 (PH-PH) = R3 + (Arc Resistance / 2)

R3 (PH-E) = R3 + Arc Resistance + Tower Footing Resistance

45
R3 = 12.36 * COS (78.91)

R3 = 2.377 Ω

R3(PH-PH) = 2.377 +(10/2)

R3(PH-PH) = 7.377 Ω

R3(PH-PE) = 2.377+10+10

R3(PH-PE)= 22.377 Ω

Zone 4

Zone4 = 0.25 *Zone1

Zone4 = 0.25*7.12

Zone4 = 1.78 Ω

tz4 = 1sec

R4= Zone 3 impedance W.R.T Secondary *COS(Line angle)

R4 (PH-PH) = R3 + (Arc Resistance / 2)
R4 (PH-E) = R3 + Arc Resistance + Tower Footing Resistance

R4 = 1.78 * COS (78.91)

R4 = 0.342 Ω

R4(PH-PH) = 0.342 +(10/2)

R4(PH-PH) = 5.342 Ω

R4(PH-PE) = 0.342+10+10

R4(PH-PE)= 20.342 Ω

1.5 Procedure for Relay setting Calculation for GE D60

Data required

1. Positive sequence Line impedance = R1+jX1

2. Zero sequence Line impedance = R0+JX0
3. CT Ratio
4. PT Ratio
5. Protected Line Length in kms

46
6. Adjacent Shortest Line Length in kms
7. Adjacent Longest Line Length in kms
8. Voltage ratio of the transformer at the remote end if any
9. MVA of the transformer at the Remote end
10. % Impedance of the transformer at remote end
11. Maximum load on the feeder in Amperes

Calculation Procedure

The relay settings are in terms of impedance that is Z

Total Positive sequence impedance of protected line with reference to primary

ZPL = [ZPL (Ohms /km)*Protected Line Length (km)]

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT ratio/PT ratio)

Positive sequence impedance Angle = Tan-1(X1/R1)

Similarly the Impedance for Adjacent Shortest Line ZSL, Adjacent Remote Long

Line ZLL and second Adjacent Long Line Z2LL can be calculated.

Total Transformer Impedance ZT (At remote end)

If there is more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

ZT = (%Transformer Impedance)*((KV) 2/ MVA)]

Zero sequence impedance Z0 = √R02+X02

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

Loadability:

The Limiting conditions for setting the distance relay reach to avoid encroachment into loads.
As per “Reliability Standard PRC-023”, The maximum impedance for the distance relay
characteristics along 30º on the impedance plane for 0.85 per unit rated voltage and the
maximum specified current for each condition.

The maximums Load w.r.t Secondary Zmax = 0.85*VL-L/ (√3*1.5*.IL)

47
Where IL corresponds to thermal limit of the conductor.

The Resistance reach corresponding to Zmax w.r.t Secondary

R = Zmax *COS (30)

The Reactance reach corresponding to Zmax w.r.t Secondary

X= Zmax *SIN (30)

The New impedance for Parallel line drawn parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts

the Resistance axis is Z new= X (at Zmax) /SIN (Line angle)

The New Resistance from Known Reactance Rnew = Znew* COS (Line angle)

Resistance reach of Relay Characteristics obtained from maximum Loadability condition

Resistive Reach R = (R correspond to Zmax – Rnew)

Zone Settings

Zone 1

Zone 1 = 80 % of Protection Line

Zone 2

48
Zone 2 = Min of [MAX of ((Protection line+ (0.5*Adjacent shortest line)) and
(1.2*Protection line)] and (Protected line + 0.5* Transformer impedance at remote
end)

tz2 = if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.3 sec

Zone 3

Zone3 = [MIN OF (1.2*Protection line + Adjacent Long line) & (Protection line + Adjacent
Long line +0.25* Adjacent Second Long Line) & (Protection line + (Transformer
impedance))]

tz3 = 1 sec

Zone 4

Zone4 = 0.25 *Zone 1

tz4 = 1 sec

Power Swing:

Inner Forward Reach = Zone 3 Reach

Outer Forward Reach = 1.2* Inner Forward Reach

49
Sample setting calculation for GE D60 Distance Relay

Substation : 400kV GSS Bhiwani

Line : 400kV Bhiwani to 400kV Hissar

Relay Name : GE D60

DATA:

Protected Line

Positive sequence Line impedance = 0.026626+j0.330931

Zero sequence Line impedance = 0.261887+j1.03144

Adjacent Short Long line

Positive sequence Line impedance = 0.026626+j0.330931

Zero sequence Line impedance = 0.261887+j1.03144

Adjacent Longest Long line

Positive sequence Line impedance = 0.026626+j0.330931

Zero sequence Line impedance = 0.261887+j1.03144

CT Ratio = 1000A/1A

PT Ratio = 400kV/110V

Protected Line Length = 32.74 km

Adjacent Shortest Line Length = 65.4 km

Adjacent Longest Line Length = 212 km

Voltage ratio of the transformer = 400kV/220kV

MVA of the transformer at the Remote end = 3*315 MVA

Impedance of the transformer = 12.52%, 12.52% & 12.52%

Maximum load on the feeder = 900 A

50
CT/PT ratio = 0.275

Calculation

Protected line

Positive sequence impedance of Protected line ZPL = √R2+X2

= √0.0266262+ 0.3309312

ZPL = 0.332 Ohms/Km

Total Positive sequence impedance of Protected line ZPL=

= [ZPL (Ohms /Km)*Protected Line Length (km)]

= [0.332 * 32.74]

ZPL W.R.T Primary = 10.869 Ω

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT/PT ratio)

= 10.84 * 0.275

ZPL = 2.989 Ω

Positive sequence impedance of Adjacent Shortest line ZPL = √R2+X2

= √0.0266262+ 0.3309312

ZSL = 0.332 Ohms/Km

Total Positive sequence impedance Adjacent Shortest ZSL=

= [Z (Ohms /Km)*Protected Line Length (km)]

= [0.332 * 65.4]

ZSL W.R.T Primary = 21.71 Ω

ZSL W.R.T Secondary = ZSL W.R.T Primary * (CT/PT ratio)

= 21.71*0.275

ZSL W.R.T Secondary = 5.97 Ω

51
Total Positive sequence impedance of Adjacent Longest line ZLL=

= [ZLL (Ohms /Km)*Longest Line Length (km)]

= [0.332* 212]

ZLL W.R.T Primary = 70.384 Ω

ZLL W.R.T Secondary = ZLL W.R.T Primary * (CT/PT ratio)

= 70.384 * 0.275

ZLL W.R.T Secondary = 19.355 Ω

Total Transformer Impedance ZT (Remote):

If there are more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

Considering Transformers are connected in parallel

Total Transformer Impedance ZT (Remote) = (% Transformer Impedance) *((kV) 2/MVA)]

Transformer Impedance of Z1 = [0.1252*(4002/315)]

= 63.59 Ω

Transformer Impedance of Z2 = [0.1252*(4002/315)]

= 63.59 Ω

Transformer Impedance of Z3 = [0.1252*(4002/315)]

= 63.59 Ω

Total Transformer Impedance ZT (Remote) = 1/((1/Z1)+ (1/Z2) + (1/Z3))

ZT (Remote) = 1/((1/63.59)+(1/3.59)+(1/63.59))

Transformer Impedance W.R.T primary ZT = 21.197 Ω

Total Transformer Impedance ZT (Remote) Secondary = ZT (Remote) *(CT/PT ratio)

= 21.197 * 0.275

Transformer Impedance W.R.T Secondary ZT = 5.829 Ω

52
Loadability

Positive sequence impedance Angle =Tan-1(X/R)

Z1= Tan-1(0.33/0.0266)

Line Angle = 85.40 Degree

The maximums Load w.r.t Secondary ZMAX primary = 0.85*VL-L/(√3*1.5*.IL)

ZMAX = 0.85* 400 / (√3*1.5*900)

[900 A is the maximum capacity of ACSR Markulla and Moose conductor]

ZMAX = 145.41 Ω

Corresponding Zmax secondary = Zmax * CT/PT Ratio = 145.41 * 0.275 = 40.01 Ω

The Resistance reach corresponding to Zmax w.r.t Secondary

R = ZMAX *COS (30)

= 40.01*0.8660

R = 34.648 Ω

The Reactance reach corresponding to Zmax w.r.t Secondary

X = ZMAX *SIN (30)

= 40.01 * 0.5

X = 20.00 Ω

The New impedance for Parallel line Drawn Parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts the Resistance axis is

Znew = X (at Zmax) /SIN(85.4)

= 20.00 / 0.9967

Znew = 20.066 Ω

The New Resistance from Known Reactance Rnew = Znew* COS (85.4)

= 20.066 *0.080

R new = 1.609

Resistances reach of Relay Characteristics

= (R corresponds to Zmax – R new)

53
 R = 34.648 -1.609

R = 33.0219 Ω

Zero sequence impedance Z0 = √R02+X02

= √0.2618872+1.031442

Z0 = 1.064 Ω

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

= Tan-1(1.03144 / 0.26188)

Z0 = 75.75 Degree

Positive sequence impedance Angle = Tan-1(X/R)

Z1= Tan-1(0.330931/0.026626)

Z1= 85.40 Degree

Zone Settings

Zone 1

Zone 1= 80 % of Protection Line

=0.8* 2.989

Zone 1 = 2.391 Ω

Zone 2

Zone 2 = MIN of [[MAX OF ((Protection line+ (0.5*Adjacent shortest line)) AND

(1.2*Protection line)]( Protection line+ (0.5*Transformer impedance at remote end)]

= Min of [[Max of [(2.989+ (0.5*5.97)) and (1.2*2.989) and (2.989 + 0.5*5.829)]

= Min of [[Max of 5.974 and 3.586] 5.90]

Zone 2 = 5.90 Ω

tz2 = if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.35 sec

tz2 = 0.35 sec

54
Zone 3

Zone3= [MIN OF (1.2(Protection line) +Adjacent Long line) & (Protection line+Adjacent Long
line+25% Second Adjacent Long Line) & (Protection line +Transformer impedance)]

= Min of (1.2*2.989+ 19.355) & (2.989+19.355+0.25*0) and (2.989+5.829)

=Min of (22.941 & 22.344 and 8.818)

Zone3 = 8.818 Ω

tz3 = 1.0 sec

Zone 4

Zone4 = 0.25 *Zone1

= 0.25* 2.3912

Zone4 = 0.5978 Ω

tz4 = 1 sec

Power Swing:

Inner Forward Reach = Zone 3 Reach

= 8.818 Ω

Outer Forward Reach = 1.2* Inner Forward Reach

= 1.2* 8.818

= 10.58 Ω

55
1.6 Procedure for Relay setting Calculation for EPAC 3000

Data required

1. Positive sequence Line impedance = R1+jX1

2. Zero sequence Line impedance = R0+JX0
3. CT Ratio
4. PT Ratio
5. Protected Line Length in kms
6. Adjacent Shortest Line Length in kms
7. Adjacent Longest Line Length in kms
8. Voltage ratio of the transformer at the remote end if any
9. MVA of the transformer at the Remote end
10. % Impedance of the transformer at remote end
11. Maximum load on the feeder in Amperes
Calculation Procedure

The relay settings are in terms of impedance that is Z

Total Positive sequence impedance of protected line with reference to primary

ZPL = [ZPL (Ohms /km)*Protected Line Length (km)]

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT ratio/PT ratio)

Positive sequence impedance Angle = Tan-1(X1/R1)

Similarly the Impedance for Adjacent Shortest Line ZSL, Adjacent Remote Long

Line ZLL and second Adjacent Long Line Z2LL can be calculated.

Total Transformer Impedance ZT (At remote end)

If there is more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

ZT = (%Transformer Impedance)*((KV) 2/ MVA)]

Zero sequence impedance Z0 = √R02+X02

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

Zone Settings

Zone 1

Zone 1 = 80 % of Protection Line

Kz 1 Zero sequence compensation

Kz1 = (Z0-Z1/3*Z1)

56
 Kz1 angle = angle of Kz1

As per manufacturer’s specification the maximum X/R ratio allowed is 10, hence considering
this limitation and the maximum loadability limit the minimum of the two is considered

Resistive reach

R1G= Minimum of [(10 times of Zone1 Reactance) and 0.8 *Resistive Reach (loadability)]

R1PH= Minimum of [(10 times of Zone1 Reactance) and 0.6 *Resistive Reach (loadability)]

Zone 2

Zone 2 = Min of [MAX OF ((Protection line+ (0.5*Adjacent shortest line)) AND

(1.2*Protection line)] and (Protected line + Transformer impedance at remote end)

tz2 = if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.3 t0 0.35 sec

Kz2 = (Z0-Z1/3*Z1)

Kz2 angle = angle of Kz2

R2G= Minimum of [(10 times of Zone1 Reactance) and 0.8 *Resistive Reach (loadability)]

R2PH= Minimum of [(10 times of Zone1 Reactance) and 0.6 *Resistive Reach (loadability)]

Zone 3

Zone3 = [MIN OF (1.2*Protection line + Adjacent Long line) & (Protection line + Adjacent
Long line +0.25* Adjacent Second Long Line) & (Protection line + (Transformer impedance at
remote end))]

R3G= Minimum of [(10 times of Zone1 Reactance) and 0.8 *Resistive Reach (loadability)]

R3PH= Minimum of [(10 times of Zone1 Reactance) and 0.6 *Resistive Reach (loadability)]

tz3 = 1 sec

Zone 4

Zone4 = 0.25 *Zone 1

tz4 = 1 sec

57
Sample setting calculation for EPAC 3000 Distance Relay

DATA:

Substation name: 220kV GSS Kurukshethra

Protected feeder: 220kV Kurukshetra to 220kV Jagadhri

Protected Line Length : 48.29 km

Adjacent Shortest Line Length : 158 km ( 220 kV Gangual )

Adjacent Longest Line Length : 158 km ( 220 kV Gangual )

Second Adjacent Longest Line : 110 km (Dhulkote)

Protected Line

Positive sequence Line impedance = 0.07411+j0.40988

Zero sequence Line impedance = 0.29524+j1.260416

Adjacent Short Long line

Positive sequence Line impedance = 0.07505+j0.415

Zero sequence Line impedance = 0.2989+j1.2804

Adjacent Longest Long line

Positive sequence Line impedance = 0.07505+j0.415

Zero sequence Line impedance = 0.2989+j1.2804

Adjacent Second Longest Long line

Positive sequence Line impedance = 0.09944+j0.4004

Zero sequence Line impedance = 0.5746+j1.9712

Nomber of Remote end Transformers : 3

Voltage Ratio of Transformer on Remote Bus: 220/132 kV

Remote end Transformer MVA: 60 MVA

% Impedance of the Remote end Transformer: 9.76 %, 10.1%, 11.1%

CT Ratio : 1200/1

58
PT Ratio : 220 kV/110 V

CT/PT Ratio: 1200/2000 = 0.6

Positive Sequence Impedance of Protected Line = √ ( R12 +X12)

=√( 0.074112+0.409882)

ZPL = 0.416 Ω/km

Total Positive Sequence of Protected Line w.r.t. Primary = ZPL * Line Length

= 0.416*48.29

=20.11Ω

Total Positive Sequence Impedance w.r.t. Secondary = 18.99 * CT/PT Ratio

= 20.11*0.6

ZPL Secondary =12.068 Ω

Positive Sequence Impedance of Shortest Line ZSL = √ ( R12 +X12)

=√( 0.075052+ 0.4152)

ZSL = 0.421 Ω/km

Total Positive Sequence of Protected Line w.r.t. Primary = ZSL * Line Length

= 0.421*158

= 66.633 Ω

Total Positive Sequence Impedance w.r.t. Secondary = ZSL * CT/PT Ratio

= 66.633 * 0.6

ZSL Secondary = 39.98 Ω

Positive Sequence Impedance of Longest Line ZLL = √ ( R12 +X12)

=√( 0.075052+ 0.4152)

ZLL = 0.421 Ω/km

Total Positive Sequence of Protected Line w.r.t. Primary = ZLL * Line Length

= 0.421*158

= 66.633 Ω

Total Positive Sequence Impedance w.r.t. Secondary = ZLL * CT/PT Ratio

59
 = 66.633 * 0.6

ZLL Secondary = 39.98 Ω

Positive Sequence Impedance of Second Longest Line Z2LL = √ ( R12 +X12)

=√( 0.099442+ 0.40042)

Z2LL = 0.412 Ω/km

Total Positive Sequence of Protected Line w.r.t. Primary = Z2LL * Line Length

= 0.412*110

= 45.38 Ω

Total Positive Sequence Impedance w.r.t. Secondary = Z2LL * CT/PT Ratio

= 66.633 * 0.6

Z2LL Secondary = 27.229 Ω

Total Transformer Impedance ZT (Remote):

If there are more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

Considering Transformers are connected in parallel

Total Transformer Impedance ZT (Remote) = (% Transformer Impedance) *((kV) 2/MVA)]

Transformer Impedance of Z1 = [0.0976*(2202/60)]

= 78.7307 Ω

Transformer Impedance of Z2 = [0.101*(2202/60)]

= 81.4733 Ω

Transformer Impedance of Z3 = [0.111*(2202/60)]

= 89.54 Ω

Total Transformer Impedance ZT (Remote) = 1/((1/Z1)+ (1/Z2) + (1/Z3))

ZT (Remote) = 1/((1/78.7307)+(1/81.4733)+(1/89.54))

Transformer Impedance W.R.T primary ZT = 27.6674 Ω

60
Total Transformer Impedance ZT (Remote) Secondary = ZT (Remote) *(CT/PT ratio)

= 27.6674 * 0.6

Transformer Impedance W.R.T Secondary ZT = 16.60 Ω

Loadability

Positive sequence impedance Angle =Tan-1(X/R)

Line Angle = Tan-1(0.40988/0.07411)

Line Angle =79.75 Degree

The maximums Load w.r.t Secondary ZMAX primary = 0.85*VL-L/(√3*1.5*.IL)

ZMAX = 0.85*220 / (√3*1.5*795)

[900 A is the maximum capacity of ACSR Markulla and Moose conductor]

ZMAX = 90.54 Ω

Corresponding Zmax secondary = Zmax * CT/PT Ratio = 90.54 * 00.6 = 54.32 Ω

The Resistance reach corresponding to Zmax w.r.t Secondary

R = ZMAX *COS (30)

= 54.32*0.8660

R = 47.05 Ω

The Reactance reach corresponding to Zmax w.r.t Secondary

X = ZMAX *SIN (30)

= 54.32 * 0.5

X = 27.16 Ω

The New impedance for Parallel line Drawn Parallel to the Line impedance passing through
Zmax to the point at which the parallel line cuts the Resistance axis is

Znew = X (at Zmax) /SIN(79.75)

= 27.16 / 0.9967

Znew = 27.60 Ω

The New Resistance from Known Reactance Rnew = Znew* COS (79.75)

= 27.60*0.01779

R new = 4.911

61
Resistances reach of Relay Characteristics

= (R corresponds to Zmax – R new)

R = 47.05 - 4.911

R = 42.13 Ω

Zone Settings

Zone 1

Zone 1= 80 % of Protection Line

= 0.8* 12.068

Zone 1 = 9.654 Ω

Kz 1 Zero sequence compensation

Kz1 = (Z0-Z1/3*Z1)

= (0.29524+j1.260416)-(0.07411+j0.40988) / 3(0.07411+j0.40988)

Zero sequence Line impedance = 0.703 ∟-4.33

Kz1 angle = angle of Kz1

Resistive reach

R1G= MIN of [(10 times of Zone1 Impedance) and 0.8*Resistive Reach at Max load)]

R1G = Min of (10* 9.654 and 0.8* 42.13)

R1G = 33.71 Ω

R1PH= MIN of [(10 times of Zone1 Impedance) and 0.6*Resistive Reach at Max load)]

R1PH = Min of (10* 9.654 and 0.8* 42.13)

R1PH= 25.28 Ω

Zone 2

Zone 2 = Min of [[MAX OF ((Protection line+ (0.5*Adjacent shortest line)) AND

(1.2*Protection line)]( Protection line+ (0.5*Transformer impedance at remote end)]

= Min of[[Max of [(12.068+ (0.5*39.98)) and (1.2*12.068)](12.068 +0.5*16.60)]

= Min of [Max of 32.058 and 14.48 ] and 20.368

Zone 2 = 20.368 Ω

62
 tz2 = 0.35 sec

Kz 1 Zero sequence compensation

Kz1 = (Z0-Z1/3*Z1)

= (0.29524+j1.260416)-(0.07411+j0.40988) / 3(0.07411+j0.40988)

Zero sequence Line impedance = 0.703 ∟-4.33

Kz1 angle = angle of Kz1

Resistive reach

R2G= MIN of [(10 times of Zone1 Impedance) and 0.8*Resistive Reach at Max load)]

R2G = Min of (10* 20.368 and 0.8* 42.13)

R2G = 33.71 Ω

R2PH= MIN of [(10 times of Zone1 Impedance) and 0.6*Resistive Reach at Max load)]

R2PH = Min of (10* 20.368 and 0.8* 42.13)

R2PH= 25.28 Ω

Zone 3

Zone3= [MIN OF (1.2(Protection line) +Adjacent Long line) & (Protection line+Adjacent Long
line+25% Second Adjacent Long Line) & (Protection line +0.8Transformer impedance)]

= Min of (1.2*12.068 + 39.98) & (12.068 +39.98 +0.25*27.229) and (12.068+ 16.60)

=Min of (54.46 and 58.855 & 28.668)

Zone3 = 28.668 Ω

tz3 = 1 sec

Resistive reach

R3G= MIN of [(10 times of Zone1 Impedance) and 0.8*Resistive Reach at Max load)]

R3G = Min of (10* 28.668 and 0.8* 42.13)

R3G = 33.71 Ω

R3PH= MIN of [(10 times of Zone1 Impedance) and 0.6*Resistive Reach at Max load)]

R3PH = Min of (10* 28.668 and 0.8* 42.13)

R3PH= 25.28 Ω

63
Zone 4

Zone4 = 0.25 *Zone1

Zone4 = 0.25*9.654 Ω

Zone4 = 2.413 Ω

tz4 = 1 sec

64
1.7 Procedure for Relay setting Calculation for Quadramho Relay

Total Positive sequence impedance of Protected line ZPL=

= [ZPL (Ohms /Km)*Protected Line Length (km)]

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT/PT ratio)

Similarly the Impedance for Adjacent Shortest Line ZSL and Adjacent Remote Long Line ZPL
can be calculated like above.

Total Transformer Impedance ZT (At remote end)

If there is more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

ZT = (%Transformer Impedance)*((KV) 2/ MVA)]

Zero sequence impedance Z0 = √R02+X02

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

Positive sequence impedance Angle = Tan-1(X1/R1)

The setting below are calculated on the basis of 1A Relay ie.In = 1.

Zone Settings

Zone 1

Zone 1= 80% of Protection Line

Phase Fault Reach

Phase reach should not exceed the Zone 1 Reach

Zph = (K1+K2)/In

Existing Setting of Zone 1 = (K11+k12+K13)*K14*Zph

K1 =1 (0 to 4 in steps of 1)

K2 = 0.8 (0 to 0.8 in steps of 0.2

K11 = 1 (1 to 9 in steps of 1)

k12 = 0 (0 to 0.9 in steps of 0.1)

k13 = 0.04 (0 to 0.08 in steps of 0.02)

K14 = 1 (1,5)

65
Zone 2

Zone 2 =Minimum of [ [MAX OF ((Protection line+ (0.5*Adjacent shortest line)) AND

(1.2*Protection line)] and ( Protected Line + 0.5 *Transformer Impedance)]

Existing setting of Zone 2 =K24*(K21+K22)*Zph

K21=1 ( 1 to 9 in steps of 1)

K22=0.6 ( 0 to 0.9 in steps of 0.1)

K24=1

tz2= if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.3 sec]

Zone 3(forward)

Zone3= [MIN OF (1.2*Protection line +Adjacent Long line)), Protection line +Adjacent Long
line+0.25*Second Long Line & Protection line + (Transformer impedance)]

Existing Setting of Zone 3 = (K31+K32)*K33*Zph

K31= ( 1 to 9 in steps of 1)

K32= ( 0 to 0.9 in steps of 0.1)

K33= (1,5)

tz3 = 0.8 sec

Zone 3 ( Offset)

Zone 4 = 0.25 *Zone 1 reach

The Existing setting of Zone 4 = (K35*K36)K33*K37*Zph

K33 = (1, 5)

K35 = (1 to 9 in steps of 1)

K36 = (0 to 0.9 in steps of 0.1)

K37 = ( 0, 0.25, 0.5, 1.0)

tz3 = 0.8 sec

Earth Fault Compensation Zn=Z0-Z1/3Z1

Zn = (K4+K5+K6) =Zph

K4 = (0 to 5 in steps of 1)

66
K5 = (0 to 0.9 in steps of 0.1

K6 = (0 to 0.08 in steps of 0.02)

Relay Characteristics angle

Relay Characteristics angle ӨPhase= Tan-1 X/R

ӨEarth = Angle Zn

Sample setting Calculation for Quadra mho relay

Substation : 400 kV GSS Bhiwani

Line : Bhiwani to Bapora 1

Relay Name : Quadramho Relay

DATA:

Protected Line Length : 6.8 km

Adjacent Shortest Line Length : 6.8 km ( 220 kV Bapora 2 )

Adjacent Longest Line Length : 6.8 km ( 220 kV Bapora 2 )

Protected Line

Positive sequence Line impedance = 0.0797 + j0.4065

Zero sequence Line impedance = 0.233 +j1.329

Adjacent Short Long line

Positive sequence Line impedance = 0.0797 + j0.4065

Zero sequence Line impedance = 0.233 +j1.329

Adjacent Longest Long line

Positive sequence Line impedance = 0.0797 + j0.4065

Zero sequence Line impedance = 0.233 +j1.329

Nomber of Remote end Transformers: 3

CT Ratio = 1200A/1A

PT Ratio = 220kV/110V

67
Protected Line Length = 6.8 Km

Adjacent Shortest Line Length = 6.8 Km

Adjacent Longest Line Length = 6.8 Km

Voltage ratio of the transformer = 220kV/132V

MVA of the transformer at the Remote end = 3*100 MVA,

Impedance of the transformer = 10.302 %, 11.87 %, 12.34%

CT/PT ratio = 0.6

Calculation

Positive sequence impedance of Protected line ZPL = √R2+X2

= √0.07972+0.40652

ZPL = 0.414 Ohms/Km

Total Positive sequence impedance of Protected line ZPL=

= [ZPL (Ohms /Km)*Protected Line Length (km)]

= [0.414 * 6.8]

ZPL W.R.T Primary = 2.8168 Ω

Total Positive Sequence Impedance of Protected Line w.r.t. Secondary

= 2.8168 *0.6

ZPL W.R.T. Secondary = 1.69 Ω

Positive sequence impedance of Shortest line ZSL = √R2+X2

= √0.07972+0.40652

ZSL = 0.414 Ohms/Km

Total Positive sequence impedance Adjacent Shortest ZSL=

= [ZSL (Ohms /Km)*Protected Line Length (km)]

= 0.414* 6.8

ZSL W.R.T. primary = 2.8168 Ω

Total Positive Sequence Impedance of the Adjacent Shortest Line w.r.t. Secondary

68
 = 2.8168 * 0.6

ZSL W.R.T. Secondary = 1.69 Ω

Positive sequence impedance of Longest line ZLL = √R2+X2

= √0.07972+0.40652

ZLL = 0.414 Ohms/Km

Total Positive sequence impedance Adjacent Longest ZLL=

= [ZLL (Ohms /Km)*Protected Line Length (km)]

= 0.414* 6.8

ZLL W.R.T. primary = 2.8168 Ω

Total Positive Sequence Impedance of the Adjacent Shortest Line w.r.t. Secondary

= 2.8168 * 0.6

ZLL W.R.T. Secondary = 1.69 Ω

Total Transformer Impedance ZT (Remote):

If there is more than one Transformer, the resultant Impedance considering the Transformers are
in parallel is taken.

Considering Transformers are connected in parallel

Total Transformer Impedance ZT (Remote) = (% Transformer Impedance) *((kV) 2/MVA)]

Transformer Impedance of Z1 = [0.1032*(2202/100)]

= 49.9488 Ω

Transformer Impedance of Z2 = [0.1187*(2202/100)]

= 57.45Ω

Transformer Impedance of Z3 = [0.1234*(2202/100)]

= 59.74496 Ω

Total Transformer Impedance ZT (Remote) = 1/((1/Z1)+ (1/Z2) + (1/Z3))

ZT (Remote) = 1/((1/49.9488)+(1/57.45)+(1/59.74496))

69
Transformer Impedance W.R.T primary ZT = 18.4503 Ω

Total Transformer Impedance ZT (Remote) Secondary = ZT (Remote) *(CT/PT ratio)

= 18.4503 * 0.6

Transformer Impedance W.R.T Secondary ZT = 11.0702 Ω

Zone Settings

Zone 1

Zone 1 = 80% of Protection Line

= 0.8*1.69

Zone 1 = 1.352 Ω

Phase Fault Reach

Phase reach should not exceed the Zone 1 Reach

Zph = (K1+K2)/In

K1+K2 = 1+0.2

Zph = 1.2

Existing Setting of Zone 1 = (K11+k12+K13)*K14*Zph

= (K11+k12+K13)*K14*1.2

= (1+0+0.08) * 1.0 *1.2 =1.296 Ω

Zone 2

Zone 2 = Min of [MAX of ((Protected line+ (0.5*Adjacent shortest line)) AND (1.2*Protected
line)] and (Protected Line + 0.5 * Transformer Impedance at remote end)

= Min of (Max Of ((1.69 + (0.5*1.69)) and (1.2*1.69)) and (1.69 + 0.5 *11.0702)

= Min of (Max of 2.535 and 2.028) and 7.2251

Zone 2 = 2.535 Ω

Existing Zone 2 setting = K24*(K21+K22)*Zph

= 1*(2+0)*1.2

= 2.4 Ω

K21=5 (1 to 9 in steps of 1)

K22=0.2 (0 to 0.9 in steps of 0.1)

70
K24=1

tz2= if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.3 sec]

tz2= 0.350 sec

Zone 3(forward)

Zone3= MIN OF [(1.2*Protected line + Adjacent Long line)), (Protected line + Adjacent Long
line+0.25* Second Adjacent Long line) & (Protected line + Transformer impedance at remote
end)]

= Min of [(1.2*1.69+1.69) and (1.69+1.69+0) and (1.69+11.0702)]

= Min of [3.718 and 3.38 and 12.7602]

= 3.38 Ω

Zone 3 = 3.38 Ω

Existing Zone 3 setting = (K31+K32)*K33*Zph

=(K31+K32)*K33*1.2

= (8+0.7)*1*1.2

= 10.44 Ω

K31 = 2 (1 to 9 in steps of 1)

K32 = 0.5 (0 to 0.9 in steps of 0.1)

K33 = 5 (1, 5)

tz3 = 1 sec

Zone 4(Reverse)

Zone 4 = 0.25 *Zone 1

Zone 4 = 0.25*1.352

Zone 4 =0.338 Ω

Existing Zone 4 ( Reverse ) = (K35+K36)K33*K37*Zph

= (1+0.1)*1*0.25*1.2 =0.33 Ω

K33=5 (1, 5)

K35=1 (1 to 9 in steps of 1)

K36=0 (0 to 0.9 in steps of 0.1)

K37=0.25 (0, 0.25, 0.5, 1.0)

71
tz3 = 1 sec

Relay Characteristics angle

Relay Characteristics angle ӨPhase= Tan-1 X/R

= Tan-1 (0.4065/0.0797)

ӨPhase = 78.90 degree

ӨEarth = Angle Positive Sequence impedance +Angle Of Kn

=78.9 + (-5)

= 74.9 Degree

72
1.8 Procedure for Relay setting Calculation for Micro Mho Relay

Total Positive sequence impedance of Protected line ZPL=

= [ZPL (Ohms /Km)*Protected Line Length (km)]

ZPL W.R.T Secondary = ZPL W.R.T Primary *(CT/PT ratio)

Similarly the Impedance for Adjacent Shortest Line ZSL and Adjacent Remote Long Line ZPL
can be calculated like above.

Total Transformer Impedance ZT (At remote end)

If there is more than one Transformer, the resultant Impedance considering the Transformers
are in parallel is taken.

ZT = (%Transformer Impedance)*((KV) 2/ MVA)]

Zero sequence impedance Z0 = √R02+X02

Zero sequence impedance Angle Z0 = Tan-1(X0/R0)

Positive sequence impedance Angle = Tan-1(X1/R1)

The setting below are calculated on the basis of 1A Relay ie.In = 1.

Zone Settings

Zone 1

Zone 1= 80% of Protection Line

Phase Fault Reach

Phase reach should not exceed the Zone 1 Reach

Zph = (K1+K2)/In

Existing Setting of Zone 1 = (K11+k12+K13)*K14*Zph

K1 =1 (0 to 4 in steps of 1)

K2 = 0.8 (0 to 0.8 in steps of 0.2

K11 = 1 (1 to 9 in steps of 1)

k12 = 0 (0 to 0.9 in steps of 0.1)

k13 = 0.04 (0 to 0.08 in steps of 0.02)

K14 = 1 (1,5)

73
Zone 2

Zone 2 =Min of [[MAX OF ((Protection line+ (0.5*Adjacent shortest line)) AND

(1.2*Protection line)] and (Protected Line + 0.5 *Transformer Impedance at remote end)]

Existing setting of Zone 2 =K24*(K21+K22)*Zph

K21=1 (1 to 9 in steps of 1)

K22=0.6 (0 to 0.9 in steps of 0.1)

K24=1

tz2= if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.3 sec]

Zone 3(forward)

Zone3= [MIN OF (1.2*Protection line +Adjacent Long line)), Protection line +Adjacent Long
line+0.25*Second Long Line & (Protection line + Transformer impedance at remote end)]

Existing Setting of Zone 3 = (K31+K32)*K33*Zph

K31= ( 1 to 9 in steps of 1)

K32= ( 0 to 0.9 in steps of 0.1)

K33= (1,5)

tz3 = 0.8 sec

Zone 3 ( Offset)

Zone 4 = 0.25 *Zone 1 reach

The Existing setting of Zone 4 = (K35*K36)K33*K37*Zph

K33 = (1, 5)

K35 = (1 to 9 in steps of 1)

K36 = (0 to 0.9 in steps of 0.1)

K37 = ( 0, 0.25, 0.5, 1.0)

tz3 = 0.8 sec

Earth Fault Compensation Zn=Z0-Z1/3Z1

74
Zn = (K4+K5+K6) =Zph

K4 = (0 to 5 in steps of 1)

K5 = (0 to 0.9 in steps of 0.1

K6 = (0 to 0.08 in steps of 0.02)

Relay Characteristics angle

Relay Characteristics angle ӨPhase= Tan-1 X/R

ӨEarth = Angle Zn

75
Sample setting Calculation for Micro mho relay

Substation : 400 kV GSS Bhiwani

Line : Bhiwani to Charkhi Dhadri

Relay Name : Micro Mho Relay

Protected line 1

Positive sequence Line impedance = 0.0797+j0.405

Zero sequence Line impedance = 0.233+j1.329

Protected line 2

Positive sequence Line impedance = 0.097105+j0.39314

Zero sequence Line impedance = 0.57146+j1.83241

Adjacent Shortest line 1

Positive sequence Line impedance = 0.0797+j0.405

Zero sequence Line impedance = 0.233+j1.329

Adjacent Shortest line 2

Positive sequence Line impedance = 0.097105+j0.39314

Zero sequence Line impedance = 0.57146+j1.83241

Adjacent Longest line

Positive sequence Line impedance = 0.097105+j0.39314

Zero sequence Line impedance = 0.57146+j1.83241

Second Adjacent longest line

Positive sequence Line impedance = 0.0741+j0.389

Zero sequence Line impedance = 0.48787+j1.92051

CT Ratio = 1200A/1A

PT Ratio = 220kV/110V

Protected Line Length = 8.7 Km (0.0797+j0.405)

Protected Line Length = 26 Km (0.097105+j0.39314)

Adjacent Shortest Line Length = 8.7 Km (0.0797+j0.405)

76
Adjacent Shortest Line Length = 26 Km (0.097105+j0.39314)

Adjacent Longest Line Length = 119.89 Km (0.097105+j0.39314)

Adjacent Second Longest Line Length = 24.73 Km (0.0741+j0.389)

Voltage ratio of the transformer at remote end = 220kV/132V

MVA of the transformer at the Remote end = 2*100 MVA

Impedance of the transformer = 12.344 %, 12.00%

CT/PT ratio = 0.6

Calculation

Total Positive sequence impedance of Protected line ZPL = √R2+X2

= (√0.07972+0.4052)*8.7+ (√0.0971052+0.393142)*26

ZPL = 14.129 Ohms/Km

Total Positive Sequence Impedance of the Protected Line w.r.t. secondary

ZPL W.R.T. Secondary = 14.129 * 0.6

= 8.4774 Ω

Total Positive sequence impedance of Shortest line ZSL = √R2+X2

= (√0.07972+0.4052)*8.7+ (√0.0971052+0.393142)*26

ZSL = 14.129 Ohms/Km

Total Positive Sequence Impedance of the Protected Line w.r.t. secondary

ZSL W.R.T. Secondary = 14.129 * 0.6

= 8.4774 Ω

Total Positive sequence impedance of Adjacent Longest line ZLL=

= [ZLL (Ohms /Km)*Longest Line Length (km)]

= √ (0.0971052+0. 393142)*119.89

ZLL W.R.T Primary = 48.55 Ω

77
Total Positive Sequence Impedance of the Adjacent Longest Line w.r.t. Secondary

ZLL W.R.T. Secondary = 48.55 * 0.6

= 29.13 Ω

Total Positive sequence impedance of Second Adjasent Longest line Z2LL=

= [Z2LL (Ohms /Km)*Longest Line Length (km)]

= √ (0.07412+0. 3892)*24.73

Z2LL W.R.T Primary = 9.7929 Ω

Total Positive Sequence Impedance of the Adjacent Longest Line w.r.t. Secondary

Z2LL W.R.T. Secondary = 9.7929 * 0.6

= 5.8757 Ω

Total Transformer Impedance ZT (Remote):

If there is more than one Transformer, the resultant Impedance considering the Transformers are
in parallel is taken.

Considering Transformers are connected in parallel

Total Transformer Impedance ZT (Remote) = (% Transformer Impedance) *((kV) 2/MVA)

Transformer Impedance Z1 = 0.12 * 2202/ 100

= 58.08 Ω

Transformer Impedance Z2 = 0.1234 * 2202/100

= 59.744 Ω

Total Transformer impedance: Zt = Z1*Z2/ (Z1 + Z2)

Zt = 58.08 * 59.744/ (58.08+ 59.744)

Zt w.r.t. primary = 29.45 Ω

Transformer Impedance w.r.t. Secondary = 29.45 * (CT/PT Ratio )

= 29.45 * 0.6

= 17.67 Ω

78
Zone Settings

Zone 1

Zone 1 = 80% of Protection Line

= 0.8*8.477

Zone 1 = 6.782 Ω

Phase Fault Reach

Phase reach should not exceed the Zone 1 Reach

Zph = (K1+K2)/In

K1+K2 = 4+0.8

Zph = 4.8

Existing Setting of Zone 1 = (K11+k12+K13)*K14*Zph

= (K11+k12+K13)*K14*4.8

= (1+0.5+0.02) * 1.0 *1.2 =7.296 Ω

Zone 2

Zone 2 = Min of [MAX of ((Protected line+ (0.5*Adjacent shortest line)) and (1.2*Protected
line)] and (Protected Line + 0.5 * Transformer Impedance)

= Min of (Max Of ((8.477 + (0.5*8.477)) and (1.2*8.477) and (8.477 + 0.5 *17.67)

= Min of (Max of 12.71 and 10.172) and 17.312

Zone 2 = 12.71 Ω

Existing Zone 2 setting =K24*(K21+K22)*Zph

K24*(K21+K22)*4.8= 12.96 Ω

K21=5 ( 1 to 9 in steps of 1)

K22=0.2 ( 0 to 0.9 in steps of 0.1)

K24=1

tz2= if [ZONE 2 > 80 % of Next shortest line then t=0.6sec else t=0.3 sec]

tz2= 0.350 sec

79
Zone 3(forward)

Zone3= Min of (1.2*Protected line + Adjacent Long line)), Protected line + Adjacent Long
line+0.25* Second Adjacent Long line) & (Protected line + Transformer impedance at remote
end)]

= Min of [(1.2*8.477+29.13)] and [8.477+29.13+0.25*5.8757] and [8.477+17.67]

= Min of [39.30 and 39.076 and 26.1477]

= 26.1477 Ω

Zone 3 = 26.1477 Ω

Existing Zone 3 setting = (K31+K32)*K33*Zph

=(K31+K32)*K33*4.8

=(9+0.4)*1*4.8= 45.12 Ω

K31 = 9 ( 1 to 9 in steps of 1)

K32 = 0.4 ( 0 to 0.9 in steps of 0.1)

K33 = 1 (1,5)

tz3 = 1 sec

Zone 4(Reverse)

Zone 4 = 0.25 *Zone 1

Zone 4 = 0.25*6.782

Zone 4 =1.695 Ω

Existing Zone 4 ( Reverse ) = (K33+K34)*Zph

(K33+K34)*4.8 = (1+0.5)*4.8 = 2.4 Ω

K33=1 (1, 5)

K34=1 (0 to 0.9 in steps of 0.1)

tz3 (Reverse) = 1 sec

80
Power Swing Blocking:

Existing setting =K50= (K51+K52)*K53*ZPH

= (6+0)*1*4.8

=28.8 Ω
Setting should be equal to the reach value of zone3 according to manufacturer’s
recommendation for detecting the Power Swing.

Earth fault compensation = (Z0-Z1)/3*Z0 *Zph

= (Total Zero Sequence Impedance - Total Positive Sequence Impedance)/

(3*Total Zero Sequence Impedance) *Zph

= (((0.57146+j1.83241)-(0.097105+j0.39314))/(3*(0.097105+j0.39314)))*4.8

= 2.312 Ω

81