3. (5 points) There is a A-Y connected, 15- MVA, 33:11 kV transformer with a differential relay protection. The CT ratio

[answerhappygod]

3 5 Points There Is A A Y Connected 15 Mva 33 11 Kv Transformer With A Differential Relay Protection The Ct Ratio 1 (40.76 KiB) Viewed 34 times

3. (5 points) There is a A-Y connected, 15- MVA, 33:11 kV transformer with a differential relay protection. The CT ratio associated with the primary side of the transformer is 400A/5A. As we learned, due to the selected standard CTs from the market, the current flowing into the relay operating coil (i.e., Ir) might not be perfectly zero in the normal situation. Hence, determine a standard CT ratio related to the secondary side of the transformer such that the current flowing into the relay operating coil is approximately 0.44 A in the normal situation. Please ensure to include all of your calculations and steps leading to the final answer. 50:5 450:5 1500:5 4000:5 100:5 500:5 1600:5 5000:5 400/5 150:5 600:5 2000:5 6000:5 m . Standard CT ratios 200:5 250:5 800:5 900:5 2400:5 2500:5 33/11 kV 300:5 1000:5 3000:5 ??? 400:5 1200:5 3200:5