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1MAC309294-MB F
Section 4
Protection functions
RER620
181
Technical Manual
input, a horizontal communication input or an internal signal of the relay program. The
influence of the
BLOCK
signal activation is preselected with the global setting
Blocking
mode
.
The
Blocking mode
setting has three blocking methods. In the “Freeze timers” mode, the
trip timer is frozen to the prevailing value. In the “Block all” mode, the whole function is
blocked and the timers are reset. the “Block TRIP output” mode, the function operates
normally but the
TRIP
output is not activated.
4.1.7.5
Application
In three-phase distribution and subtransmission network applications the phase
discontinuity in one phase can cause increase of zero sequence voltage and short
overvoltage peaks and also oscillation in the corresponding phase.
46PD is a three-phase protection with DT characteristic, designed for detecting broken
conductors in distribution and subtransmission networks. The function is applicable for
both overhead lines and underground cables.
The operation of 46PD is based on the ratio of positive and negative sequence currents.
This gives better sensitivity and stability compared to plain negative sequence current
protection since the calculated ratio of positive and negative sequence currents is relatively
constant during load variations.
When the three phase currents are measured, the positive sequence current is calculated:
(Equation 28)
The negative sequence current is calculated:
(Equation 29)
phase current vectors
phase rotation operator (defined to rotate a phasor component forward by 120 degrees)
The unbalance of the network is detected by monitoring the negative and positive sequence
current ratio, where the negative sequence current value is I
2
and I
1
is the positive
sequence current value. The unbalance is calculated:
(Equation 30)
Broken conductor fault situation can occur in phase A in a feeder.
I
Ia aIb a Ic
1
1
3
2
=
+
+
⎛
⎝⎜
⎞
⎠⎟
I
Ia a Ib aIc
2
1
3
2
=
+
+
⎛
⎝⎜
⎞
⎠⎟
Ia Ib Ic
, ,
a
Iratio
I
I
=
2
1
Summary of Contents for RER620
Page 2: ......
Page 22: ...Section 1MAC309294 MB F 16 RER620 Technical Manual ...
Page 88: ...Section 3 1MAC309294 MB F Basic functions 82 RER620 Technical Manual ...
Page 278: ...Section 4 1MAC309294 MB F Protection functions 272 RER620 Technical Manual ...
Page 362: ...Section 5 1MAC309294 MB F Control functions 356 RER620 Technical Manual ...
Page 418: ...Section 7 1MAC309294 MB F Measurement functions 412 RER620 Technical Manual ...
Page 428: ...Section 8 1MAC309294 MB F Recording functions 422 RER620 Technical Manual ...
Page 464: ...Section 9 1MAC309294 MB F Other functions 458 RER620 Technical Manual ...
Page 554: ...Section 10 1MAC309294 MB F General function block features 548 RER620 Technical Manual ...
Page 568: ...Section 12 1MAC309294 MB F Relay physical connections 562 RER620 Technical Manual ...
Page 574: ...Section 13 1MAC309294 MB F Technical data 568 RER620 Technical Manual ...
Page 576: ...Section 14 1MAC309294 MB F Relay and functionality tests 570 RER620 Technical Manual ...
Page 578: ...Section 15 1MAC309294 MB F Applicable standards and regulations 572 RER620 Technical Manual ...
Page 582: ...Section 16 1MAC309294 MB F Glossary 576 RER620 Technical Manual ...
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