P44x/EN AD/E44 Update Documentation
Page 36/82
MiCOM P441, P442 & P444
2.18.3 Aided DEF protection schemes
The option of using separate channels for DEF aided tripping, and distance protection
schemes, is offered in the P441, P442 and P444 relays. Since C1.0 a better sensitivity has
been created by using a settable threshold for the residual current in case of reverse
fault for creating quicker blocking scheme logic.
The IN Rev factor can be adjusted from 10% to 100% of IN
As well in case of independent channel logic with a blocking scheme an independent
transmission timer Tp has been created with a short step at : 2ms
When a separate channel for DEF is used, the above DEF schemes are independently
selectable. When a common signalling channel is employed, the distance and DEF must
Share a common scheme. In this case a permissive overreach or blocking distance scheme
must be used. The aided tripping schemes can perform single pole tripping.
The relay has aided scheme settings as shown in the following table:
Menu text Default setting Setting range Step size
Min Max
GROUP 1
AIDED D.E.F.
Aided DEF Status Enabled Disabled or Enabled
Polarisation Zero Sequence Zero Sequence or Negative Sequence
V> Voltage Set 1V 0.5V 20V 0.01V
IN Forward 0.1 x In 0.05 x In 4 x In 0.01 x In
Time Delay 0 0 10s 0.1s
Scheme Logic Shared Shared, Blocking or Permissive
Tripping Three Phase Three Phase or Single Phase
Tp (if blocking scheme not
shared)
2ms 0 ms 1000ms 2ms
IN Rev Factor 0,6 0 10s 0.1s
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