Allen-Bradley Rockwell Automation 857 User Manual page 4

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Table of Contents
Chapter 3
Protection Functions
857-UM001A-EN-P - July 2009
Maximum Number of Protection Stages ................................ 3-1
Protection Functions ............................................................... 3-1
General Features of Protection Stages .................................... 3-2
Setting Groups .................................................................. 3-2
Forcing Start or Trip Condition for Testing ..................... 3-2
Forcing Start or Trip Condition for Testing Purposes ...... 3-2
Start and Trip Signals ....................................................... 3-3
Output Matrix ................................................................... 3-3
Blocking ........................................................................... 3-3
Retardation Time .............................................................. 3-3
Reset Time (Release Time) .............................................. 3-4
Hysteresis or Dead Band .................................................. 3-5
Function Dependencies ........................................................... 3-5
Application Modes ........................................................... 3-5
Current Protection Function Dependencies ...................... 3-6
Overcurrent Stage I> (50/51) .................................................. 3-6
Three Independent Stages ................................................ 3-6
Inverse Operation Time .................................................... 3-6
Inverse Time Limitation ................................................... 3-7
Cold Load and Inrush Current Handling .......................... 3-7
Setting Groups .................................................................. 3-7
Recorded Values of the Latest Eight Faults ..................... 3-9
Directional Overcurrent Protection I
Four Independent Stages ................................................ 3-12
Inverse Operation Time .................................................. 3-12
Inverse Time Limitation ................................................. 3-12
Cold Load and Inrush Current Handling ........................ 3-12
Setting Groups ................................................................ 3-12
Recorded Values of the Latest Eight Faults ................... 3-15
Broken Line Protection I
Current Unbalance Protection I
Inverse Delay ................................................................. 3-17
More Stages (Definite Time Delay only) ....................... 3-17
Setting Groups ................................................................ 3-17
Recorded Values of the Latest Eight Faults ................... 3-19
Incorrect Phase Sequence Protection I
Stall Protection Ist> (48) ....................................................... 3-19
Frequent Start Protection N> (66) ........................................ 3-21
Undercurrent Protection I< (37) ........................................... 3-23
Directional Earth Fault Protection I
Polarization .................................................................... 3-24
Modes for Different Network Types .............................. 3-24
Input Signal Selection .................................................... 3-25
Intermittent Earth Fault Detection .................................. 3-25
Two Independent Stages ................................................ 3-25
Inverse Operation Time .................................................. 3-26
Inverse Time Limitation ................................................. 3-26
Setting Groups ................................................................ 3-26
Recorded Values of the Latest Eight Faults ................... 3-29
> (67) ........................ 3-10
dir
/I > (46R) ..................................... 3-15
2 1
> (46) ................................. 3-16
2
>> (47) .................... 3-19
2
> (67N) ...................... 3-23
dir