Distribution transformer
transformer that provides the final voltage transformation in an electric power distribution system
A distribution transformer or service transformer is a transformer that provides a final voltage reduction in the electric power distribution system, stepping down the voltage used in the distribution lines to the level used by the customer. The invention of a practical, efficient transformer made AC power distribution feasible; a system using distribution transformers was demonstrated as early as 1882.
If mounted on a utility pole, they are called pole-mount transformers. When placed either at ground level or underground, distribution transformers are mounted on concrete pads and locked in steel cases, thus known as distribution tap pad-mounted transformers.
Distribution transformers typically have ratings less than 200 kVA, although some national standards allow units up to 5000 kVA to be described as distribution transformers. Since distribution transformers are energized 24 hours a day (even when they don't carry any load), reducing iron losses is vital in their design. They usually don't operate at full load, so they are designed to have maximum efficiency at lower loads. To have better efficiency, voltage regulation in these transformers is kept to a minimum. Hence, they are designed to have small leakage reactance.
Types
Distribution transformers are classified into different categories based on factors such as:
Mounting location – pole, pad, underground vault
Type of insulation – liquid-immersed or dry-type
Number of phases – single-phase or three-phase
Voltage class
Basic impulse insulation level (BIL).
“Distribution transformer” enters the record as transformer that provides the final voltage transformation in an electric power distribution system. Crown Archives preserves that source wording while asking what Distribution, transformer and provides can confirm, complicate or overturn.
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