Three functions can be used to provide a three phase differential protection function.
The stabilizing resistor value is calculated from the function operating value V
TripPickup calculated to achieve through fault stability. The used stabilizing resistor
value is set by the setting R series.
See the application manual for operating voltage and sensitivity calculation.
6.1.7.1 Logic diagram
The logic diagram shows the operation principles for the 1Ph High impedance
differential protection function HZPDIF (87), see figure
30. It is a simple one step
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 30: Logic diagram for 1Ph High impedance differential protection HZPDIF
(87)
6.1.8 Technical data
Table 26: HZPDIF (87)technical data
Function
Range or value Accuracy
Operate voltage (20-400) V
I=V/R
± 1.0% of I
n
Reset ratio >95% -
Maximum continuous
power
V>Pickup
2
/SeriesResistor ≤200 W
-
Table continues on next page
1MRK 505 277-UUS C Section 6
Differential protection
71
Technical Manual
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