Ashida ADR241B, Instruction Manual

Page: 96 / 272

ADR241B
Doc ID : ADR241B-DO_IM_01
Ref ID : ADR241B/IM/PLF
Rev No. : 06
Page No. : 96 of 272
&
IDMT/
DT
IEn Enable =
Yes
IE>n Trip
IE>n Pickup
IN Ground Current
IE>n
+
-
Figure 5: Logic Diagram for the Ground over current
Where n=1 to 2 stages of Ground over current.
The Ground over Current logic checks the Measured Ground current is exceed the pickup
value (IE>n) and calculated operating time based on the curve selected in the IE>n Curve
setting and IE>n TMS or tIE>n DT Delay parameter settings. After satisfied all the above
condition the IED generates the Ground over current trip.
4.5.2 Residual Over current (50N/51N)
Residual Over-current function operates for a set value of current with time delay (IDMT/DT).
This function provided with two stages, Where Stage 1 (3I0>1) can be programmed as IDMT
or Definite Time (DT) provided with the Range of 2% to 250% in step of 1%. All major
international IDMT curves as well as Definite Time and User Define curves are available. The
Stage 2 (3I0>2) can be programmed as Instantaneous or Definite Time (DT) provided with
the Range of 5% to 3000% in step of 1%.
The following diagram figure 6 explains about the Residual over current protection function.
&
IDMT/
DT
3I0 Enable = Yes
Trip
Pickup
3I0 Residual
Current
3I0>n
+
-
Figure 6: Logic Diagram for the Residual over current
Where n=1 to 2 stages of Residual over Current.
The Residual over Current logic checks the Derived Ground current is exceed the pickup
value (3Io>n) and calculated operating time based on the curve selected in the 3Io>n Curve
setting and 3Io>n TMS or t3Io>n DT Delay parameter settings. After satisfied all the above
condition the IED generates the Residual over current trip.
As ADR241B support 2 earth fault (IE and 3Io) various connection can possible as per
system requirement