Transformer reset requires the signed volt-seconds to balance so flux returns instead of walking toward saturation. The zero-sum rows are exact ideal-reset ledgers carried through the turns ratio; real reset margins depend on core material, saturation limit, leakage, winding resistance, timing error, and voltage measurement uncertainty.
Balanced primary reset rows imply balanced secondary volt-seconds. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Primary volt-second balance carries through the turns ratio
Each row balances primary volt-seconds first, then derives the secondary reset sum from the transformer ratio.
∑VpΔt=0V⋅s;∑VsΔt=0V⋅s
Three primary voltage rows keep both volt-second sums at zero
Different primary voltages still pass when the reset interval uses the matched opposite area.