Knowledge

Q: How does an SR circuit work for HV testing, and why does it amplify voltage? A: At resonance: ωL = 1/(ωC). The only remaining impedance

The hipot test is done, and HV is off. Can I walk up and touch the test piece now? Absolutely not. Stored energy in the specimen can be lethal: E = &f

Q: Given P₀ and Pₖ from tests, how do I calculate efficiency at different load levels? A: Efficiency η = P_out / (P_out + P₀ + β² ×

Q: What is load loss, what causes it, and how do we measure it? A: Load loss (Pₖ) is the power dissipated in the windings due to load current and stra

Q: What exactly is no-load loss, and what does the test procedure look like? A: No-load loss (P₀), also called iron loss or core loss, is the power co

During the test, I saw a large spark and the relay tripped. Was it a flashover or a breakdown - and how do I tell the difference? Distinguishing flash

What is the basis for selecting the test voltage for an AC Hipot test? Test voltage is determined by the equipment's rated insulation level (Um, B

What exactly does the AC Hipot test verify, and why is it "destructive" yet indispensable? The AC Hipot test applies an AC voltage significa

Q: I hear about the "Duval Triangle" a lot in DGA interpretation. How does it work? A: The Duval Triangle (by Michel Duval, IREQ, now IEEE C

Q: Should I install an on-line DGA monitor, or continue sending oil samples to the lab? A: Each method has a distinct role. The choice depends on tran

Q: How should transformer oil be sampled for DGA, and what are the most common sampling mistakes? A: DGA results are only as reliable as the sampling

I have a DGA report with concentrations of seven gases. How do I turn these numbers into a diagnosis? A: Three internationally recognized ratio method