IEEE DRAFT C37.110 : D21 OCT 94

1. INTRODUCTION
2. REFERENCES
3. DEFINITIONS
4. CURRENT TRANSFORMERS CHARACTERISTICS AND
     CLASSIFICATION
     4.1 Current Transformer Equivalent Circuit and
          Phasor Diagrams
     4.2 Current Transformer Secondary Excitation
          Characteristics
     4.3 Knee-Point Voltage
     4.4 Current Transformer Accuracy
     4.5 Dynamic Characteristics
     4.6 The Effects of Remanence
     4.7 Fundamental Transformer Equation
5. GENERAL APPLICATION OF CURRENT TRANSFORMERS
     5.1 Current Transformers Burdens
     5.2 Ratio Selection
     5.3 Long-Term and Short-Term Thermal Ratings
     5.4 Current Transformer Secondary Output Accuracy
          Class Voltage
     5.5 Connecting Current Transformers in Series
     5.6 Three Phase Connections
     5.7 Auxiliary Current Transformers
     5.8 Bus Configuration
     5.9 Current transformer Location
     5.10 Minimizing the Effects of Current Transformer
          Saturation
     5.11 Determining Current Transformer Steady State
          Performance Using Secondary Excitation Curves
6. EFFECTS OF CURRENT TRANSFORMER SATURATION ON RELAYS
     6.1 Saturation Effects on Electro-mechanical Relays
     6.2 Saturation Effects on Static Relays
     6.3 Saturation Effects on Differential Relays
7. SPECIFIC APPLICATIONS OF CURRENT TRANSFORMERS
     7.1 Overcurrent Relays
     7.2 Differential Protection
     7.3 Distance Protection
     7.4 Other types of High-Speed Protection
8. BIBLIOGRAPHY
Appendix 1. IEC Standards on Current Transformers
Appendix 2. List of IEEE Standard C Values and Burdens
Appendix 3. Remanent Flux in Current Transformers

 

          

Covers the characteristics and classification of current transformers (cts) used for protective relaying. Also describes the conditions which cause the ct output to be distorted and the effects on relaying systems of this distortion. Selection and application of cts for the more common protection schemes are also addressed.