IEEE DRAFT C57.13.3 : D9 2005

Introduction
1. Overview
   1.1 Scope
   1.2 Purpose
2. References
3. Definitions
4. Need for Grounding Secondary Circuits of Instrument
   Transformers and Cases
5. Grounding of Instrument Transformer Secondary Circuits
   5.1 Background
   5.2 Ground Connection to only One Point in the Secondary Circuit
   4.3 Recommended Point of Grounding
   5.4 Location of Connection to Ground
       5.4.1 Unused secondary windings of instrument transformers
   5.5 Minimum Size of Conductor for Ground Connection
   5.6 Ground Connection Isolation Test Facilities
       5.6.1 VT Secondary Circuits
       5.6.2 CT Secondary Circuits
6. Grounding of Instrument Transformer Cases and Cases of Connected
   Equipment
   6.1 Metallic or Conductive Case Grounding
   6.2 Internal Conductive Parts - Insulated Cases
   6.3 Ungrounded Metallic or Conductive Cases
7. Exceptions to Grounding
8. Grounding of Low-Energy Transducers
   8.1 Interconnection Wiring Practices
Annex A (informative) Issues to consider for shielded cable
                      applications for instrument transformers
   A.1 CTs installed over shielded cables, metal bushing collars
       or conduits
Annex B (informative) IEEE Standards Reviewed by the WG
Annex C (informative) Article 90.2 Scope of NFPA 70, National
                      Electrical Code [1]
Annex D (informative) Survey of Grounding Practices
Annex E (informative) Bibliography

Includes the grounding practices presently used and the practices that were not previously reported. It provides information on the grounding of: - secondary circuits of electromagnetic current transformer (CT) and voltage transformer (VT) circuits, - cases of relays, CTs and VTs and, - secondary circuits of opto-electronic CTs and VTs.