Electric utility engineering reference book by westinghouse pdf

Examples of

Overcurrent Relays

and

Distribution Fuse Elements

Curves

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Distribution Fuse Curves. Reproduced from the Distribution Systems Electric Utility Reference Book by the Electric Utility Engineers of

the Westinghouse Electric Corporation. East Pittsburgh, Pennsylvania, U.S.A., 1959.

Type K

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Distribution Fuse Curves. Reproduced from the Distribution Systems Electric Utility Reference Book by the Electric Utility Engineers of

the Westinghouse Electric Corporation. East Pittsburgh, Pennsylvania, U.S.A., 1959.

Type T

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41-100K

22

CO (HI-LO) Overcurrent Relay

Curve 418248

Figure 17: Typical Time Curve of the Type CO-8 Relay

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41-100K

23

CO (HI-LO) Overcurrent Relay

Curve 418249

Figure 18: Typical Time Curve of the Type CO-9 Relay

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41-100K

24

CO (HI-LO) Overcurrent Relay

Sub 2 288B655

Figure 19: Typical Time Curve of the Type CO-11 Relay

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EE493 Fall 2000

“STANDARD” RELAY CURVES Formula for modern relays

TDc M a

t b 

   

+ −

= 1

Typical American relay curves (ANSI/IEEE)

Curve type a b c Moderately inverse 0.0515 0.02 0.1140

Very inverse 19.61 2 0.491 Extremely inverse 28.2 2 0.1217

Note: TD = 0.5, 1, …, 11 Typical European curves (IEC)

Curve type a b c Normal inverse 0.14 0.02 (*)

Very inverse 13.5 1 (*) Extremely inverse 80 2 (*) Long time inverse 120 1 (*)

Note: TD = 0.05, 0.1, …, 1.1 (*) c depends on the precise relay type and manufacturer

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3-12 Overcurrent Protection Date Code 20031008 SEL-501/501-1 Instruction Manual

TIME-OVERCURRENT ELEMENT OPERATE/RESET CURVE EQUATIONS

tp = operating time tr = induction-disk emulation reset time TD = 51 time-dial setting M = applied multiples of pickup current

US Moderately Inverse Curve: U1

� �

� � �

�

� �

� �

� � �

�

� �

2

02.0

M1 08.1

•TDtr

1M 0104.0

0.0226•TDtp

US Inverse Curve: U2

� �

� � �

�

� �

� �

� � �

�

� �

2

2

M1 95.5

•TDtr

1M 95.5

1800.•TDtp

US Very Inverse Curve: U3

� �

� � �

�

� �

� �

� � �

�

� �

2

2

M1 88.3

•TDtr

1M 88.3

9630.0•TDtp

US Extremely Inverse Curve: U4

� �

� � �

�

� �

� �

� � �

�

� �

2

2

M1 67.5

•TDtr

1M 67.5

3520.0•TDtp

IEC Class A Curve: C1 (Standard Inverse)

� �

� � �

�

� �

� �

� � �

�

� �

2

02.0

M1 5.13

•TDtr

1M 14.0

•TDtp

IEC Class B Curve: C2 (Very Inverse)

� �

� � �

�

� �

� �

� � �

�

� �

2M1 3.47

•TDtr

1M 5.13

•TDtp

IEC Class C Curve: C3 (Extremely Inverse)

� �

� � �

�

� �

� �

� � �

�

� �

2

2

M1 0.80

•TDtr

1M 0.80

•TDtp

IEC Long Time Inverse: C4

� �

� � �

�

� �

� �

� � �

�

� �

M1 0.120

•TDtr

1M 0.120

•TDtp

Full-sized time-current curve transparencies are available from the factory.

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Date Code 20031008 Overcurrent Protection 3-13 SEL-501/501-1 Instruction Manual

Figure 3.2: Time Curve U1 Figure 3.3: Time Curve U2

Figure 3.4: Time Curve U3 Figure 3.5: Time Curve U4

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3-14 Overcurrent Protection Date Code 20031008 SEL-501/501-1 Instruction Manual

Figure 3.6: Time Curve C1 Figure 3.7: Time Curve C2

Figure 3.8: Time Curve C3 Figure 3.9: Time Curve C4

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14 Siemens SIP 3.1 ⋅ 1999

Functions

SIPROTEC 4 7SJ61/62/63 / 6MD63 Multifunction Protection Relay and Bay Controller

n Protection functions

Time-overcurrent protec- tion (ANSI 50, 50N, 51, 51N)

This function is based on the phase-selective measure- ment of the three phase cur- rents and the ground current (four transformers). Two definite-time overcurrent pro- tection elements (DMT) exist both for the phases and for the ground. The current threshold and the delay time can be set in a wide range. As an option, inverse-time overcurrent protection characteristics (IDMTL) can be activated:

Fig. 28

Definite-time overcurrent protection

Fig. 32

Definite inverse Fig. 31

Long inverse t =

− +

 

   ⋅

5 6143 1

2 18592 .

. M

TD t = −

+  

   ⋅

0 4797

1 0 21359

1 5625

. .

.M TD

Fig. 30

Short inverse t =

− +

 

   ⋅

0 2663

1 0 03393

1 2969

. .

.M TD

Inverse-time overcurrent char- acteristics to ANSI/ IEEE • Inverse • Short inverse • Long inverse • Moderately inverse • Very inverse • Extremely inverse • Definite inverse

Notes on Fig. 29 to 32: Scope of M from 1.1 to 20

Fig. 29

Inverse t =

− +

 

   ⋅

8 9341 1

0 17966 2 0938

. .

.M TD

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Siemens SIP 3.1 ⋅ 1999 15Siemens SIP 3.1 ⋅ 1999 15

Fig. 33

Reset Moderately inverse

Fig. 36

Very inverse Fig. 35

Reset Very inverse

Fig. 34

Moderately inverse

t = −

+  

   ⋅

3 922 1

0 0982 .

. M

TD 2

Tripping time characteristics of the definite-time overcurrent protection according to ANSI (IEEE) C37.112 t = tripping time in seconds M = multiples of pickup setting

range 0.1 to 4 TD = time dial

Reset characteristics

For easier time coordination with electromechanical re- lays, reset characteristics ac- cording to ANSI standard C37.112 are applied. The determination of the time sequence is carried out by integration of time con- stants according to the char- acteristics for all currents above the reset threshold. See Fig. 33, 35, 37

t = −

+  

   ⋅

0 0103 1

0 0228 .

. M

TD 0.02

t reset 2= ⋅ −

4 32 1

. TD M

t reset 2= ⋅ −

0 97 1

. TD M

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16 Siemens SIP 3.1 ⋅ 1999

SIPROTEC 4 7SJ61/62/63 6MD63 Multifunction Protection Relay and Bay Controller

Functions

Tripping time characteristics of the definite-time overcurrent protection according to ANSI (IEEE) t = tripping time in seconds M = multiples of pickup setting

range 0.1 to 4 TD = time dial

Fig. 37

Reset Extremely inverse

Fig. 38

Extremely inverse t =

− +

 

   ⋅

5 64

1 0 0243

2

. .

M TDt reset 2=

⋅ −

5 82 1

. TD M

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Siemens SIP 3.1 ⋅ 1999 17Siemens SIP 3.1 ⋅ 1999 17

Fig. 39

Inverse

Fig. 42

Long inverse Fig. 41

Extremely inverse

Fig. 40

Very inverse

( ) t T=

− ⋅

120 1I I p

p

Inverse time - overcurrent characteristics according to IEC standard

( ) t T=

− ⋅

13 5 1

, I I p

p

( ) t T=

− ⋅

80

1I I p 2 p

( ) t T=

− ⋅

0 14

1 00 02

, ,

I I p p

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Examples of
Curves_Standard_Formulas.pdf