IEEE C37.108-2002

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 under fault
       conditions
3.1 Primary feeder faults
3.2 Network equipment 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
4 Methods available to provide improved network
       transformer protection
4.1 Electrical detection of faults
4.1.1 Differential relays
4.1.2 Overcurrent relays and fuses
4.1.3 Ground-fault relays
4.1.4 Compensator distance 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 Bibliography
Figure
1 Typical network system
Appendices
A Response of network relays to system faults
B Example
C Other concepts being investigated
Appendix Figures
A1 Typical tripping characteristics of master relay
A2 Typical closing characteristics of master and
       phasing relays
B1 Example of a network transformer vault protection
       scheme
B2 High voltage coordination
B3 Low voltage coordination

Provides guidelines for the application of network protectors. The use of network transformers and protectors with distributed resources is addressed.