Single Phase Transformer


A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core, and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is called mutual induction.

Transformer Single phase-100 kvA Circuit

Circuit Symbols

Two windings and an iron core, step-up or step-down as windings are different ratios.
Transformer with two windings and an iron core.
Transformer with three windings, two secondary windings.
Transformer with an earth screen.

Selecting a single phase transformer:

single phase transformer.JPG

Uses of Transformers:

  • Electric power transmission over long distances.
  • High-voltage direct-current HVDC power transmission systems
  • Large, specially constructed power transformers are used for electric arc furnaces used in steelmaking.
  • Rotating transformers are designed so that one winding turns while the other remains stationary. A common use was the video head system as used in VHS and Beta video tape players. These can pass power or radio signals from a stationary mounting to a rotating mechanism, or radar antenna.

  • Sliding transformers can pass power or signals from a stationary mounting to a moving part such as a machine tool head. An example is the linear variable differential transformer,
  • Some rotary transformers are precisely constructed in order to measure distances or angles. Usually they have a single primary and two or more secondaries, and electronic circuits measure the different amplitudes of the currents in the secondaries, such as in synchros and resolvers.

  • Small transformers are often used to isolate and link different parts of radio receivers and audio amplifiers, converting high current low voltage circuits to low current high voltage, or vice versa.
  • Balanced-to-unbalanced conversion. A special type of transformer called a balun is used in radio and audio circuits to convert between balanced circuits and unbalanced transmission lines such as antenna downleads. A balanced line is one in which the two conductors (signal and return) have the same impedance to ground: twisted pair and "balanced twin" are examples. Unbalanced lines include coaxial cables and strip-line traces on printed circuit boards. A similar use is for connecting the "single ended" input stages of an amplifier to the high-powered "push-pull" output stage.

Transformers basics - Video

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