ADR233B
Ref ID : ADR233B/IM/PS
Rev No. : 05
Page No. : 137 of 479
Blocking of a protection function can be prevented if “Disable” is selected in the relevant setting.
Blocking of a protection function can be enabled if “Enabled” is selected in the relevant setting.
Through each function setting menu, the user can set a 2nd Harmonic blocking threshold and
block each over current/ Earth fault and sequence over current protection functions. The relay
also provided with “I>UB2H” setting, If fundamental current is become more than this setting
relay will disable the blocking function.
4.9 Non Directional Phase Over current (50/51) Protection (W1/W2)
Non Directional Phase Over-current function operate for a set value of current with time delay
(IDMT/DT) and operate for any phase current.
There are three independent stages for W1/ W2 Phase over current Protections. The following
diagram explains about the phase over current protection function.
&
Maximum Phase
Current
(
A/
B
/C
)
IP>
n
IP
>
n
= Enable
+
-
IP> n Trip
IP>
n Pkp
IDMT
/
DT
Note
n = 1
, 2,
3 stages
Figure 14: Logic Diagram for the W1/ W2 phase over current
Where n=1, 2, 3 stages of Over Current.
The same logic will be applicable for all stages
The Phase over Current logic checks the phase currents are exceeds the pickup value (IP>n)
and calculated operating time based on the curve selected in the IP>n Curve setting and IP>n
TMS or tIP>n Delay or IP>n Time Dial parameter settings. After satisfied all the above condition
the IED generates the phase over current trip. Once the Pickup signal will be asserted then it
will reset after the drop out time calculated by IDMT/DT Dropout characteristics.
4.10 Non Directional Ground Over current (50/N/51N)
Non Directional ground Over-current function operates for a set value of current with time delay
(IDMT/DT).
There are three independent stages for Ground over current Protections. The following diagram
explains about the Ground over current protection function.
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