ABB Relion 670 series, Technical Reference Manual

Page: 168 / 1232

5.2.3 Principle of operation
The 1Ph High impedance differential protection (HZPDIF, 87) function is based on
one current input with external stabilizing resistor and voltage dependent resistor.
Three functions can be used to provide a three phase differential protection function.
The stabilizing resistor value is calculated from the IED function operating value V
TripPickup calculated to achieve through fault stability. The supplied stabilizing
resistor has a link to allow setting of the correct resistance value .
See the application manual for operating voltage and sensitivity calculation.
5.2.3.1 Logic diagram
The logic diagram shows the operation principles for the 1Ph High impedance
differential protection function HZPDIF (87), see figure
65 . It is a simple one step IED
function with an additional lower alarm level. By activating inputs, the HZPDIF (87)
function can either be blocked completely, or only the trip output.
AlarmPickup
AlarmPickup
0-tAlarm
0
0.03s
0
en05000301_ansi.vsd
ANSI05000301 V1 EN
Figure 65: Logic diagram for 1Ph High impedance differential protection HZPDIF
(87)
Section 5
1MRK505222-UUS C
Differential protection
162
Technical reference manual