Allen-Bradley Rockwell Automation 857 User Manual page 6

iv
Table of Contents
Chapter 3
Protection Functions
(cont.)
857-UM001A-EN-P - July 2009
Overfrequency and Underfrequency Protection f>, f<
(81H/81L) .................................................................... 3-57
Protection Mode for f>< and f><>< Stages ................... 3-57
Undervoltage Self Blocking of Underfrequency Stages .. 3-57
Initial Self Blocking of Underfrequency Stages ............. 3-57
Four Independent Frequency Stages .............................. 3-57
Setting Groups ................................................................ 3-57
Recorded Values of the Latest Eight Faults ................... 3-59
Rate of Change of Frequency (ROCOF) Protection df/dt (81R) ..3-59
Frequency Behavior During Load Switching ................. 3-59
Description of ROCOF Implementation ........................ 3-60
ROCOF and Frequency Over and Under Stages ............ 3-60
Definite Operation Time Characteristics ........................ 3-60
Inverse Operation Time Characteristics ......................... 3-61
Synchrocheck Protection (25) ............................................... 3-63
Circuit-breaker Failure Protection CBFP (50BF) ................. 3-70
Recorded Values of the Latest Eight Faults ................... 3-70
Programmable Stages (99) .................................................... 3-71
Eight Independent Stages ............................................... 3-73
Setting Groups ................................................................ 3-73
Recorded Values of the Latest Eight Faults ................... 3-73
Arc Fault Protection (50ARC/50NARC) (optional) ............. 3-74
Three Stages for Arc Faults ............................................ 3-74
Light Channel Selection ................................................. 3-74
Binary Input ................................................................... 3-75
Binary Output ................................................................. 3-75
Delayed Light Indication Signal .................................... 3-75
Pick-up Scaling .............................................................. 3-75
Recorded Values of the Latest Eight Faults ................... 3-77
Inverse Time Operation ........................................................ 3-77
Stage Specific Inverse Delay .......................................... 3-77
Operation Modes ............................................................ 3-77
Local Panel Graph .......................................................... 3-78
Inverse Time Setting Error Signal .................................. 3-78
Limitation ....................................................................... 3-78
Standard Inverse Delays IEC, IEEE, IEEE2, RI ............ 3-80
IEC Inverse Time Operation .................................... 3-80
IEEE/ANSI Inverse Time Operation ....................... 3-83
IEEE2 Inverse Time Operation ............................... 3-86
RI and RXIDG type Inverse Time Operation .......... 3-88
Free Parametrisation using IEC, IEEE and IEEE2
Equations ................................................................. 3-90
Programmable Inverse Time Curves .............................. 3-91
Inverse Time Setting Error Signal .................................. 3-91
Limitations ..................................................................... 3-91