Transformers are critical power system components, allowing transmission and distribution of power throughout the industry. As NETA Certified Technicians, we should be familiar with the various sizes, configurations, and types of transformers.
1. Which type of transformer is usually connected to a utility generator?
a. Step-down transformer
b. Isolation transformer
c. Step-up transformer
d. Three winding transformer
2. What does the DY1 designation on a transformer mean?
a. Delta high side with 1 low-side wye winding
b. Delta low side with 1 high-side wye winding
c. Delta-wye tap position 1
d. Delta-wye clock position 1
3. Using the nameplate data, how is the transformer’s maximum fault current calculated?
a. Divide the secondary rated current by the impedance
b. Multiply the secondary current by the primary tap
c. Multiply the primary available fault current by 20
d. The available fault current is always listed in kA on the nameplate.
4. What creates a phase shift on a delta–wye transformer?
a. The transformer winding connections
b. The transformer system coupling
c. The transformer magnetization
d. The transformer grounding
5. What is the main benefit of a core-ground strap?
a. Visual grounding
b. Single-point grounding
c. A torqued ground connection
d. Online partial discharge (PD) monitoring
6. What needs to be verified before handling transformer insulating oil (such as taking an oil sample for testing)?
a. Lead content
b. Asbestos content
c. PCB content
d. Acetylene content
7. What is a third winding typically called on a three-winding transformer?
a. Tertiary winding
b. Spare winding
c. LV winding
d. Unused winding
