IEEE DRAFT C37.108 : D6 98

1 Introduction
1.1 Scope
1.2 References
2 General background
2.1 Network development
2.2 Application considerations of adding protection to spot
       network vaults versus grid network vaults
3 Operation of a network transformer vault under fault
       conditions
3.1 Primary feeder faults
3.2.1 High-voltage switch faults
3.2.2 Transformer faults
3.2.3 Protector faults
3.2.4 Low-voltage bus faults
3.2.5 Low-voltage faults in customer supply cables and bus
3.2.6 Other faults
3.2.7 High voltage cable faults
4 Methods available to provide improved network transformer
       protection
4.1 Electrical detection of faults
4.1.1 Transformer differential relays
4.1.2 Overcurrent relays and fuses
4.1.3 Ground-fault relays
4.1.4 Compensator distance relays
4.1.5 Network protector relays
4.2 Mechanical detection of faults
4.2.1 Sudden-pressure relay (gas)
4.2.2 Sudden-pressure relay (gas/oil)
4.3 Thermal detection of faults
4.3.1 Heat detection
4.3.2 Smoke detection
4.4 Ultraviolet detectors
5 High-voltage fault interrupting devices
5.1 Circuit breakers
5.2 Remotely located circuit breakers with transfer tripping
5.3 Fault interrupters
5.4 Power fuses and current-limiting fuses
6 Low-voltage fault interrupting devices
6.1 Network protector
6.2 Low-voltage fuses
7 Distributed source generation
8 Network distribution SCADA
9 Bibliography
Appendixes
Appendix A Response of network relays to system faults
A1 Tripping characteristics
A2 Balanced faults
A3 Tripping operations on unbalanced faults
A4 Reclosing characteristics
Appendix B Example: 12.5 kV/277Y/480 V spot vault network
                      transformer protection
NOTES for fig B1, B2, B3
Appendix C Other concepts being investigated
C1 Low-voltage arcing fault detection
C2 Microprocessor based current differential relays
C3 Current-limiting fuses and three-phase load break
            switch
Figure 1 Typical network system
Figure A-1 Typical closing characteristics of master and
            phasing relays
Figure A-2 Typical tripping characteristics of master relay
Figure B-1 Example of a network transformer vault protection
            scheme
Figure B-2 High voltage coordination
Figure B-3 Low voltage coordination