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1MAC309294-MB F
Section 4
Protection functions
RER620
251
Technical Manual
4.5.3.5
Application
Electric power lines experience faults for many reasons. In most cases, electrical faults
manifest in mechanical damage, which must be repaired before returning the line to
service.
Most of these faults are ground faults. Conventional protection systems based on
overcurrent, impedance, or other principles are suitable for detecting relatively low
impedance faults, which have a relatively large fault current.
However, a small percentage of the ground faults have a very large impedance. They are
comparable to load impedance and consequently have very little fault current. These high
impedance faults do not pose imminent danger to power system equipment. However, they
are a considerable threat to people and property. The IEEE Power System Relay
Committee working group on High Impedance Fault Detection Technology defines High
Impedance Faults as those that 'do not produce enough fault current to be detectable by
conventional overcurrent relays or fuses'.
High impedance fault (HIZ) detection requires a different approach than that for
conventional low impedance faults. Reliable detection of HIZ provides safety to humans
and animals. HIZ detection can also prevent fire and minimize property damage. ABB has
developed innovative technology for high impedance fault detection with over seven years
of research resulting in many successful field tests.
Summary of Contents for RER620
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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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