In the example, what ratio is used to convert 4160 V to 416 V with a potential transformer?

In the example, what ratio is used to convert 4160 V to 416 V with a potential transformer?

• A. 10:1
• B. 5:1
• C. 1:10
• D. 4:1

Answer: (A)

Potential transformers reduce high line voltages by a turns ratio. The secondary voltage equals the primary voltage divided by the turns ratio (Np/Ns). A ratio of 10:1 means ten turns on the primary for every one on the secondary, so the secondary voltage is one-tenth of the primary. Therefore 4160 V becomes 416 V when using a 10:1 ratio. The other ratios would produce different voltages: 5:1 would give 832 V, 1:10 would step up to 41,600 V, and 4:1 would yield 1,040 V.

Potential transformers reduce high line voltages by a turns ratio. The secondary voltage equals the primary voltage divided by the turns ratio (Np/Ns). A ratio of 10:1 means ten turns on the primary for every one on the secondary, so the secondary voltage is one-tenth of the primary. Therefore 4160 V becomes 416 V when using a 10:1 ratio. The other ratios would produce different voltages: 5:1 would give 832 V, 1:10 would step up to 41,600 V, and 4:1 would yield 1,040 V.