IEEE DRAFT C37.20.4 : 2001

1 Scope
2 References
3 Definitions
3.1 Switch
3.2 Interrupter switch
3.3 Unfused switch
3.4 Fused switch
3.5 Integral switch and fuse
3.6 Ground switch
3.7 Disconnecting switch (isolating switch)
3.8 Bypass switch
3.9 Selector switch
3.10 Service disconnect
3.11 Design test
3.12 Production test
3.13 Conformance test
3.14 Field test
3.15 Tin surfaced or equivalent
4 Service conditions
5 Ratings
5.1 General
5.2 Required ratings
5.2.1 Load current interrupter switches
5.2.2 Disconnectors, transfer, or selector switches
5.2.3 Grounding switches
5.3 Rated maximum voltage
5.4 Rated lightning impulse withstand voltage
5.5 Rated power frequency withstand voltage
5.6 Rated power frequency
5.7 Rated continuous current
5.8 Rated load switching current
5.9 Rated momentary withstand current
5.10 Rated short-time withstand current
5.11 Rated short-time withstand current duration
5.12 Rated fault making current
5.13 Rated fault making current for integral switch and
      fuse (optional)
5.14 Rated control voltage
5.15 Rated cable-charging switching current (optional)
5.16 Rated unloaded transformer switching current (optional)
5.17 Rated direct acting fuse tripping current (optional)
5.18 Temperature limitations
5.18.1 Limiting temperatures
5.18.2 Temperature limits for insulating materials
5.18.3 Temperature limits for switch conducting parts
6 Test
6.1 General
6.2 Design test
6.2.1 Dielectric test
6.2.2 Continuous current test
6.2.3 Momentary and short-time current test
6.2.4 Fault making test
6.2.5 Mechanical operation test
6.2.6 Load switching current test
6.2.7 Cable-charging current switching test (optional)
6.2.8 Unloaded-transformer switching test (optional)
6.2.9 Direct acting fuse switching test
6.3 Production tests
6.4 Conformance tests
6.5 Field test
7 Construction
7.1 General requirements
7.1.1 Primary connections
7.1.2 Insulating materials
7.2 Functional components
7.2.1 Contact position indicator
7.2.2 Stored energy indicator
7.2.3 Locking
7.2.4 Nameplate markings
8 Application guide
8.1 General
8.2 Voltage
8.3 Frequency
8.4 Continuous current
8.5 Short-circuit current
8.6 cable charging current
8.7 Unloaded transformer switching capability
8.8 Direct acting fuse tripping
8.8 Unusual service conditions
8.9 Maintenance
Figure 1 Momentary and fault making test circuits
Figure 2 Dielectric test

Covers indoor AC medium-voltage switches for use in enclosures for application in power circuits at voltages above 1kV through 38kV as follows: stationary or drawout; manual or power operation; fused or unfused.