NEIEP Mechanics Practice Exam

What happens when a secondary winding is open?

1. The output voltage increases

2. The secondary resistance will be zero

3. The secondary resistance will be infinity

4. The circuit will short circuit

The correct answer is: The secondary resistance will be infinity

When a secondary winding is open, it means that there is a break in the connection of the winding, preventing current from flowing through it. In this scenario, the resistance of the secondary winding becomes infinitely high because without a closed loop for current to travel through, it cannot conduct electricity. Hence, the electrical behavior is akin to an open circuit, where the resistance is considered to be infinite. This concept is critical in understanding transformer operations and electrical circuits in general. An open secondary winding implies no current flow, which leads to a situation where the voltage can exist but does not produce any load current, thus effectively contributing to an infinite resistance condition.