A 120-V/24-V control transformer with a 20 VA rating can supply about 0.83 amps on the 24-V side.

Prepare for the essential 636 Period 3 Motor Final Test with comprehensive flashcards and detailed questions. Access explanations and hints for each question to ace your exam!

Multiple Choice

A 120-V/24-V control transformer with a 20 VA rating can supply about 0.83 amps on the 24-V side.

The key idea is that the VA rating tells the maximum apparent power the transformer can deliver. With a 20 VA rating, the secondary current equals 20 VA divided by the secondary voltage. So on the 24-V side, the maximum current is 20 / 24 ≈ 0.833 A. That is about 0.83 amps, which makes the statement true. For context, the same VA rating on the primary would correspond to 20 / 120 ≈ 0.167 A, showing the trade-off between voltage and current across the transformer. The other numbers come from using the wrong side or misapplying the rating: 0.17 A is the primary current, not the secondary, and 2.0 A would require 48 VA on the secondary, exceeding the rating.

The key idea is that the VA rating tells the maximum apparent power the transformer can deliver. With a 20 VA rating, the secondary current equals 20 VA divided by the secondary voltage. So on the 24-V side, the maximum current is 20 / 24 ≈ 0.833 A. That is about 0.83 amps, which makes the statement true.

For context, the same VA rating on the primary would correspond to 20 / 120 ≈ 0.167 A, showing the trade-off between voltage and current across the transformer. The other numbers come from using the wrong side or misapplying the rating: 0.17 A is the primary current, not the secondary, and 2.0 A would require 48 VA on the secondary, exceeding the rating.

More practice questions