ABB 615 series Technical Manual page 20

Table of contents
14
Technical data............................................................................ 499
Technical revision history........................................................... 499
Stabilized and instantaneous differential protection for two-
winding transformers 87T................................................................ 500
Identification............................................................................... 500
Function block............................................................................ 500
Functionality............................................................................... 500
Operation principle..................................................................... 501
Application.................................................................................. 514
CT connections and transformation ratio correction...................527
Signals........................................................................................531
Settings.......................................................................................532
Monitored data............................................................................534
Technical data............................................................................ 537
Technical revision history........................................................... 537
Numerically stabilized low-impedance restricted ground-fault
protection 87LOZREF......................................................................538
Identification............................................................................... 538
Function block............................................................................ 538
Functionality............................................................................... 538
Operation principle..................................................................... 538
Application.................................................................................. 542
Signals........................................................................................548
Settings.......................................................................................548
Monitored data............................................................................549
Technical data............................................................................ 549
Technical revision history........................................................... 550
High-impedance differential protection 87A, 87B, 87C....................550
Identification............................................................................... 550
Function block............................................................................ 550
Functionality............................................................................... 551
Operation principle..................................................................... 551
Application.................................................................................. 553
Example calculations for busbar high-impedance differential
protection....................................................................................561
Signals........................................................................................564
Settings.......................................................................................565
Monitored data............................................................................567
Technical data............................................................................ 567
Technical revision history........................................................... 568
615 series ANSI
Technical Manual