Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

What reading indicates a properly functioning transformer on an ohmmeter?

1. A finite reading

2. An infinite reading

3. A fluctuating reading

4. Zero resistance

The correct answer is: A finite reading

A finite reading on an ohmmeter indicates a properly functioning transformer because it shows that there is a measurable amount of resistance in the primary and secondary windings of the transformer. This resistance is essential for the transformers' coils to function correctly without short circuits or open circuits. If the resistance were infinite, it would suggest an open circuit, meaning there is a break in the winding, and the transformer would not operate. Conversely, a reading of zero resistance would indicate a short circuit, which is also a failure state. Fluctuating readings can imply inconsistent or intermittent connections, which could indicate faulty wiring or components. Therefore, a finite reading signifies that the windings are intact, showing good condition and functionality for the transformer.