Technical description
Table of Contents
VM55.EN005
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Table of Contents
Introduction .......................................................................... 40
Main features ................................................................... 40
Principles of numerical protection techniques .......... 41
Protection functions ............................................................. 44
Maximum number of protection stages in one
application ................................................................................ 44
General features of protection stages ........................ 44
List of protection functions ............................................. 49
Overvoltage protection U> (59) ................................... 50
Volts/hertz over-excitation protection U
< (27P) .............................. 56
Undervoltage protection U< (27) ................................. 60
Zero sequence voltage protection U
Overfrequency and underfrequency Protection f>, f<
(81H/81L) ................................................................................... 66
Synchrocheck (25) .......................................................... 69
Circuit breaker failure protection CBFP (50BF) ........... 76
Programmable stages (99) ............................................ 78
Supporting functions ............................................................ 82
Event log ........................................................................... 82
Disturbance recorder ..................................................... 84
Voltage sags and swells ................................................. 88
Voltage interruptions ...................................................... 90
Voltage transformer supervision ................................... 92
System clock and synchronization ............................... 93
Self-supervision ................................................................. 97
Diagnostics .............................................................. 97
Measurement functions ....................................................... 99
Measurement accuracy ................................................ 99
Minimum and maximum values.................................. 100
Voltage measurement modes .................................... 100
Symmetric components ............................................... 101
Primary, secondary and per unit scaling................... 105
Voltage scaling ..................................................... 105
Analogue output (option) ........................................... 108
mA scaling example ............................................ 108
Control functions ................................................................ 109
Output relays ................................................................. 109
Digital inputs ................................................................... 110
Virtual inputs and outputs ............................................ 112
Function keys / F1 & F2 ................................................. 113
Output matrix ................................................................. 114
Blocking matrix .............................................................. 115