Track every core lot, winding and loss test from tender to nameplate.

A transformer order starts as a tender with a kVA rating, voltage ratio, vector group, impedance and loss limits. You price core steel, winding copper or aluminium, insulation, oil and tank, then commit to no-load and load loss figures that the customer can penalise. The design sheet comes next. It fixes core dimensions, turns per coil and the tap range, and the shop cuts every lamination and orders the oil from it.

Silicon steel coils are slit and cut into laminations, stacked into the core, and wound coils are fitted over the limbs. The active part is dried, lowered into the tank, filled with oil and fitted with bushings, tap changer and radiators. Routine tests follow. A buyer’s inspector may attend. A unit above its quoted loss is a financial problem, not just a technical one.

The design office releases a sheet while the core shop is cutting from a steel coil that has not been weighed in. The winding section is short by two reels of strip, and nobody has raised the purchase order. Three units sit on the bench. The inspector cannot come before Thursday.

Meanwhile a utility buyer asks for the loss report of a unit shipped last year. One engineer remembers it was on the bay computer. Finding the file is another matter. It takes an hour. Sometimes more.