Question 8062 of 749 · Maryland Journeyperson Electrician Exam
A small control transformer has a primary current of 5 A and primary protection only. What is the maximum primary overcurrent device rating?
Exactly one answer is correct.
You got of questions right. Here on the question pages nobody remembers which ones you got wrong. The trainer saves your progress and asks the mistakes again until they stick.
Or free: the 10 questions most people get wrong
Show solution
Correct answer to question 8062
- A: 167 percent of rated primary current
Explanation
Table 450.3(B) allows 167 percent for primary currents less than 9 A but 2 A or more, when only primary protection is provided. Small transformers have relatively high magnetizing inrush.
More questions: Motors, HVAC, Generators and Transformers
- 8063A transformer with primary-only protection has a rated primary current below 2 A. What is the maximum primary overcurrent device rating?
- 8064A transformer rated 1000 volts or less has both primary and secondary protection. What is the maximum primary device rating?
- 8065With primary and secondary protection, what is the maximum secondary device rating for a transformer with a secondary current of 9 A or more?
- 8066A 45 kVA, 480 volt three-phase transformer has primary-only protection. What is the maximum standard primary breaker size?
- 8067What must be done regarding the ventilation of a transformer?
- 8068A 75 kVA dry-type transformer is installed indoors. What is the minimum separation from combustible material without a fire-resistant barrier?