Blog
Working notes on transformer design from the engineers building the calculation chain: losses, impedance, short-circuit withstand, evaluated cost and the state of the market.
- Why large power transformers are tall: coil height, impedance and flux
On a large unit the flux limit fixes the turns, and the impedance band then decides how tall the windings must be. Get the height wrong at the start and no amount of iteration will close the design.
- Copper or aluminium windings: what really changes in the design
Aluminium is lighter and usually cheaper per ampere, but it needs about 60 % more conductor area. That extra area moves the core, the impedance and the tank, not just the bill of materials.
- One design, many standards: what changes when you design for export
Moving from IS or IEC to IEEE, DOE, EU Ecodesign or Australian MEPS changes the reference temperature, the tolerances and sometimes what is being guaranteed at all.
- Energy efficiency levels and star ratings for distribution transformers
India's IS 1180 efficiency levels and the BEE star label set the losses a distribution transformer may have. Here is how the limits work and what it takes to move up a level.
- Why transformer lead times blew out, and what it means for your quote
Grid expansion, renewables and data centres arrived at the same time as a thin supply base. The winners are the suppliers who can price a compliant design in hours.
- How to read a guarantee sheet before you agree to it
No-load loss, load loss, impedance and temperature rise are four promises with very different tolerances and very different consequences when you miss them.
- Where no-load loss really comes from
The W/kg figure on the steel datasheet is measured on an Epstein frame. Your core is not an Epstein frame, and the gap between them has a name.
- Impedance and the tap range: the check most spreadsheets skip
Reactance is computed from the radial build. Move the taps and the build moves with them, which is why a design can pass at principal tap and fail at the extremes.
- Short-circuit forces in plain terms
Radial hoop stress, axial compression and thermal withstand are three separate failures with three separate causes. Passing one says nothing about the other two.
- Total owning cost, not first cost
Loss capitalisation turns a purchasing decision into an engineering one. If you are not designing against the buyer's A and B factors, you are designing against the wrong objective.
- From spreadsheet to verified engine: what we learned porting a legacy design tool
Every legacy design tool contains undocumented judgement. Finding it means running the old tool and the new one side by side until the last discrepancy has a reason.