Section 1: Common Functions ................................................................................................................................. 6

1.1 Overview ................................................................................................................................................. 6

1.2 Before Testing ......................................................................................................................................... 6

1.2.1

Safety ........................................................................................................................................ 6

1.2.2

Sequence of Tests .................................................................................................................... 6

1.2.3

Test Equipment ......................................................................................................................... 7

1.2.4

Use of PC to facilitate testing .................................................................................................... 7

1.2.5

Precautions ............................................................................................................................... 7

1.2.6

Applying Settings ...................................................................................................................... 7

1.3 Tests ....................................................................................................................................................... 8

1.3.1

Inspection.................................................................................................................................. 8

1.3.2

Secondary Injection Tests ......................................................................................................... 8

1.3.3

Primary Injection Tests ............................................................................................................. 8

1.3.4

Putting into Service ................................................................................................................... 8

1.4 AC Analogue Energising Quantities ........................................................................................................ 9

1.5 Binary Inputs ........................................................................................................................................... 9

1.6 Binary Outputs ...................................................................................................................................... 10

1.7 Relay Case Shorting Contacts .............................................................................................................. 10

Section 2: Protection Functions ............................................................................................................................. 11

2.1 Phase Directional Polarity Check .......................................................................................................... 12

2.1.1

2 out of 3 logic ......................................................................................................................... 13

2.2 Phase Overcurrent (67/50,67/51) .......................................................................................................... 14

2.2.1

Definite Time Overcurrent

2.2.2

Inverse Time Overcurrent (51) .............................................................................................. 15

2.3 Voltage Controlled Overcurrent (51V) ................................................................................................... 17

2.4 Cold Load (51C) .................................................................................................................................... 19

2.4.1

Inverse Time Overcurrent (51C) ........................................................................................... 20

2.5 Arc Flash Detection (50AFD) ................................................................................................................ 23

2.6 Directional Earth Fault Polarity Check (67N) ......................................................................................... 24

2.7 Derived Earth Fault (67/50N, 67/51N) ................................................................................................... 25

2.7.1

Directional Polarity .................................................................................................................. 26

2.7.2

Definite Time Overcurrent

2.7.3

Inverse Time Overcurrent (51N) ........................................................................................... 26

2.8 Measured Earth fault (67/50G,67/51G) ................................................................................................. 29

2.8.1

Directional Polarity .................................................................................................................. 30

2.8.2

Definite Time Overcurrent

2.8.3

Inverse Time Overcurrent (67/51G) ...................................................................................... 30

2.9 Sensitive Earth fault (67/50S,67/51S) ................................................................................................... 33

2.9.1

Directional Polarity .................................................................................................................. 33

2.9.2

Definite Time Overcurrent

2.9.3

Wattmetric Protection .............................................................................................................. 34

2.9.4

Inverse Time Overcurrent (51SEF) ....................................................................................... 35

2.10 Restricted Earth fault (64H) ................................................................................................................. 37

2.11 Negative Phase Sequence Overcurrent (46NPS) ................................................................................. 39

2.11.1

Definite Time NPS Overcurrent

2.11.2

Inverse Time NPS Overcurrent (46IT) .................................................................................. 40

2.12 Undercurrent (37) ................................................................................................................................ 42

2.13 Thermal Overload (49) .......................................................................................................................... 44

2.14 Over/Under Voltage .............................................................................................................................. 46

2.14.1

Phase Under/Over Voltage (27/59) ........................................................................................ 46

2.14.2

Undervoltage Guard (27/59UVG) ............................................................................................ 48

2.14.3

NPS Overvoltage (47) ............................................................................................................. 48

2.14.4

Undervoltage Guard (47 U/V Guard) ...................................................................................... 49

2.14.5

Neutral Overvoltage (59N) ...................................................................................................... 50

2.14.6

Definite Time (59NDT) ............................................................................................................ 50

2.14.7

Inverse Time (59NIT) .............................................................................................................. 50

2.15 Under/Over Frequency (81) .................................................................................................................. 52

2.16 Power (32) ............................................................................................................................................ 54

7SR11 & 7SR12 Commissioning and Maintenance Guide

(50) ............................................................................................. 14

(50N) .......................................................................................... 26

(67/50G) ..................................................................................... 30

(50SEF) ...................................................................................... 34

(46DT) ............................................................................... 40

Chapter 6 Page 3 of 72

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