Rockwell Automation 865 Differential Protection Relay - Manual (Page 7)

Table of Contents v
865-UM001A-EN-P – July 2009
Chapter 8
Applications Restricted Earth Fault Protection .............................................8-1
Restricted Earth Fault Protection for a Transformer
With Neutral Connection ................................................. 8-2
CT Requirements ............................................................. 8-2
Calculating the Stabilizing Resistance R
S
, VDR Value,
and Actual Sensitivity ................................................ 8-3
Value of Stabilizing Resistor R
S
...................................... 8-3
Voltage Limitation ........................................................... 8-3
Actual Operating Sensitivity ............................................ 8-4
Current Transformer Selection ............................................... 8-5
CT Classification according IEC 60044-1, 1996 ............. 8-5
CT Requirement for Protection ........................................ 8-8
Protection of a Dyn11 Transformer ...................................... 8-11
Protection of a YNd11 Transformer ..................................... 8-13
Protection of Generator and Block Transformer .................. 8-14
Application Example of Differential Protection
using Allen-Bradley 865 Relay ...................................... 8-15
Trip Circuit Supervision ...................................................... 8-16
Chapter 9
Connections Rear Panel View ......................................................................9-1
Auxiliary Voltage ................................................................... 9-5
Serial Communication Connectors ......................................... 9-5
Front Panel Connector ...................................................... 9-5
Rear Panel Connector X5 (REMOTE) ............................. 9-5
X4 Rear Panel Connector (Local RS232 and
Extension RS485 ports) ............................................. 9-7
Optional Two-Channel Arc Protection Card .......................... 9-8
Optional Digital I/O Card (DI19/DI20) .................................. 9-8
Connection Examples ............................................................. 9-9