Wednesday, 6 December 2017


By Ask Biomedical

Power Distribution Transformers are used to efficiently distribute
electricity from generating plants to industrial, commercial and residential areas.
Step-up transformers boost voltages up to 765,000 volts for easy transmission,
using small sized conductors. Step-down transformer are use to meet local higher current demands at 480, 277, 240, 208 and 120 volt requirements.

Autotransformers use one continuous winding through both the primary
and secondary on the same iron-core. The primary and secondary serve in the
same magnetic circuit causing current to flow in parts of the same winding. The main advantage of autotransformers are economical construction, and operating efficiency in low ratio situations like reduced-voltage motor starters.

Current Transformers (CT’s) are used when the a.c. currents are too large for measuring instruments such as power company kilowatt-hour meters. They work on the same principle as the clamp-on ammeter by sensing current flow through a conductor without having to break the circuit.

Constant-Current Transformers produce a constant secondary amperage to
a load even though the primary input amperage changes. By using a movable primary coil, air space between coils can be varied. This causes magnetic leakage
between the coils, and varies current flow in the secondary. A typical example of the use of these transformers are series street-lighting systems.


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