4.4.2.5
Application
In three-phase distribution and subtransmission network applications the phase
discontinuity in one phase can cause an 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-sequence and negative-sequence
currents. This gives better sensitivity and stability compared to plain negative-sequence
current protection since the calculated ratio of positive-sequence and negative-sequence
currents is relatively constant during load variations.
The unbalance of the network is detected by monitoring the negative-sequence 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 with the equation.
Iratio
I
I
=
2
1
A070702 V2 EN
(Equation 116)
Broken conductor fault situation can occur in phase A in a feeder.
IECA070699-ANSI V1 EN
Figure 301:
Broken conductor fault in phase A in a distribution or subtransmission
feeder
Section 4
1MAC059074-MB A
Protection functions
596
615 series ANSI
Technical Manual
Summary of Contents for Relion 615 series
Page 1: ... RELION PROTECTION AND CONTROL 615 series ANSI Technical Manual ...
Page 2: ......
Page 39: ...Section 17 Glossary 1181 Table of contents 615 series ANSI 33 Technical Manual ...
Page 40: ...34 ...
Page 64: ...58 ...
Page 216: ...210 ...
Page 884: ...878 ...
Page 1038: ...1032 ...
Page 1136: ...1130 ...
Page 1172: ...1166 ...
Page 1180: ...1174 ...
Page 1186: ...1180 ...
Page 1192: ...1186 ...
Page 1193: ...1187 ...
Page 1194: ......
Page 1195: ......