56
Distance protection (ZM)
Chapter 4
Line distance
1
Distance protection (ZM)
1.1
Application
The ZM distance protection function provides fast and reliable protection for overhead lines and
power cables in all kinds of power networks. For each independent distance protection zone, full
scheme design provides continuous measurement of impedance separately in three independent
phase-to-phase measuring loops as well as in three independent phase-to-earth measuring loops.
Phase-to-phase distance protection is suitable as a basic protection function against two- and
three-phase faults in all kinds of networks, regardless of the treatment of the neutral point. Inde-
pendent setting of the reach in the reactive and the resistive direction for each zone separately,
makes it possible to create fast and selective short circuit protection in power systems.
Phase-to-earth distance protection serves as basic earth fault protection in networks with directly
or low impedance earthed networks. Together with the independent phase preference logic, it
also serves as selective protection function at cross-country faults in isolated or resonantly
earthed networks.
Independent reactive reach setting for phase-to-phase and for phase-to-earth measurement se-
cures high selectivity in networks with different protective relays used for short-circuit and
earth-fault protection.
Summary of Contents for REL 501-C1 2.5
Page 1: ...Technical reference manual Line distance protection terminal REL 501 C1 2 5 ...
Page 2: ......
Page 26: ...14 Introduction to the technical reference manual Chapter 1 Introduction ...
Page 42: ...30 Technical data Chapter 2 General ...
Page 66: ...54 Blocking of signals during test BST Chapter 3 Common functions ...
Page 142: ...130 Time delayed overvoltage protection TOV Chapter 6 Voltage ...
Page 162: ...150 Autorecloser AR Chapter 9 Control ...
Page 174: ...162 Event function EV Chapter 10 Logic ...
Page 210: ...198 Serial communication Chapter 12 Data communication ...
Page 226: ...214 Serial communication modules SCM Chapter 13 Hardware modules ...
Page 230: ...218 Terminal diagrams Chapter 14 Diagrams Figure 87 REL 501 C1 with DC switch ...
Page 234: ...222 Terminal diagrams Chapter 14 Diagrams ...
Page 237: ......