Definition
A transformer in which the secondary winding has more turns than the primary winding, producing an output voltage higher than the input voltage. The increase in voltage is accompanied by a proportional decrease in current, since a transformer does not create power.
Plain English
An electrical device that takes a lower voltage in and gives a higher voltage out. Whatever extra voltage you gain, you lose in current — the total power stays the same.
Context Anchor
Seen in aircraft electrical and ignition-system discussions, especially where low voltage must be raised high enough to make a spark.
Derivation
‘Transformer’ comes from Latin trans- (across) and forma (shape) — a device that ‘changes the form’ of electrical energy. ‘Step-up’ simply describes the direction of the change: voltage is stepped up rather than down.
Why Pilots Care
Aircraft systems such as magnetos or certain transmitters require higher voltages than the main battery or alternator supply; the transformer ensures those components receive the voltage they need to operate reliably.
Intuition Check
A step-up transformer does not create extra electrical power from nothing. It raises voltage, usually by trading away current.
Example Sentence 1
The aircraft uses a step-up transformer to raise the 28-volt bus output to the higher voltage required by the fluorescent cabin lights.
Example Sentence 2
Before flight, the pilot confirmed that the avionics step-up transformer was supplying the required voltage to the communication radios.