cesgibis
Electrical
- Jan 21, 2003
- 26
Hi,
1) I've been told that CT (for protection) should not be used to detect a fault current which is less than 10% of its nominal current because acuracy decreases. Is this true ? if yes Is this applicable for toroid CTs (CBCTs) also ?
2) I have to select a CT (toroid) to install on the neutral link to earth of a HV/LV 2500kVA transformer for earth fault protection. Neutral system is TT (neutal not distributed). What should be the ratio of this CT ? and how sensitive can it be ?
Thanks for your answers
1) I've been told that CT (for protection) should not be used to detect a fault current which is less than 10% of its nominal current because acuracy decreases. Is this true ? if yes Is this applicable for toroid CTs (CBCTs) also ?
2) I have to select a CT (toroid) to install on the neutral link to earth of a HV/LV 2500kVA transformer for earth fault protection. Neutral system is TT (neutal not distributed). What should be the ratio of this CT ? and how sensitive can it be ?
Thanks for your answers
