A reset-interval-balances-core-volt-seconds scan checks that primary and secondary volt-second ledgers both close over the switching cycle. The 12 V on interval and -6 V reset interval balance to 0 V*s only for the stated ideal coupled-reset rows. Real transformers add magnetizing-current limits, leakage inductance, core loss, saturation margin, winding resistance, timing error, finite precision, and measurement uncertainty.
Repeatable switching needs a source-bound reset balance. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A reset pair must first balance primary volt-seconds
The coupled reset check is downstream of an accepted primary balance and the same transformer voltage row.
∑VpΔt=0V⋅s⇒∑VsΔt=0V⋅s
Balanced primary rows give balanced secondary rows
Each scan row uses one accepted primary on/off pair and one matching transformer voltage.