6 Current and Voltage T ransformers - CIGRE（6 T ransformersCIGRE电流和电压）.pdf

• 6 • C u r r e n t a n d V o l t a g e T r a n s f o r m e r s Introduction 6.1 Electromagnetic voltage transformers 6.2 Capacitor voltage transformers 6.3 Current transformers 6.4 Novel instrument transformers 6.5 • 6 • C u r re nt and Vo l tage Tra ns for me r s 6.1 INTRODUCTION Whenever the values of voltage or current in a power circuit are too high to permit convenient direct connection of measuring instruments or relays, coupling is made through transformers. Such measuring transformers are required to produce a scaled down replica of the input quantity to the accuracy expected