Final answer:
The rated power output of a transformer is given on the nameplate in volts-amps (VA) or kilovolts-amps (kVA). Transformers operate with high efficiency, usually over 99%, and use the transformer equation Pp = IpVp = IsVs = Ps to relate power, current, and voltage between primary and secondary coils.
Step-by-step explanation:
The rated power output (capacity) of a transformer is typically given on the nameplate in volts-amps (VA) or kilovolts-amps (kVA). This indicates the maximum amount of power the transformer can handle without exceeding its design limits.
Transformers function based on the transformer equation, which relates the primary and secondary voltage levels to the number of coils or loops in the transformer. This equation is given by Pp = IpVp = IsVs = Ps, where P is the power, I is the current, and V is the voltage. The efficiency of a transformer is typically high, often exceeding 99%, meaning that the power output is nearly equivalent to the power input when resistance is negligible.
A step-up transformer increases voltage from the primary to the secondary coil, while a step-down transformer decreases it. The design of the transformer and the ratio of the number of coils in the primary and secondary windings determine whether the output voltage is higher or lower than the input voltage. Additionally, some transformers offer variable outputs by allowing connections at various points on the secondary coil.