## Sunday, February 12, 2023

The transformer makes it possible to transfer energy (in alternating form) from a

source has a load, while changing the voltage value. The voltage can be either ˆ

raised or lowered depending on the intended use. The change from a voltage level ´ to a `

another is done by the effect of a magnetic field. ´

Among the applications of transformers, we note:

1. Electronics: ´

(a) low voltage power supply `

(b) impedance matching ´

2. Electrical engineering: ´

(a) voltage transformation for the transmission and distribution of electricity

(b) low voltage power supply (e.g. halogen lamps)

3. Measurement:

(a) current transformers ´

(b) potential transformers

There are two main types of transformers, the battleship type and the columnar type.

In the breastplate type, a magnetic circuit with three branches is used, and the windings

are around the central branch. In the columnar type, a magnetic circuit with two

columns is used.´

The transformer consists of two (or more) windings coupled on a core.

magnetic, as in Figure 8.1. The side of the source is called the primary, and has

N1 wire windings (turns). The side of the load is called the secondary and has N2

windings. The flux ϕ is the mutual flux. The “•” indicates the polarity of the voltages. By

convention, a current that enters a “•” indicates a positive flow

Note that there is no electrical connection between the primary and the ´

secondary. All coupling between the two windings is magnetic. ´

When an alternating voltage is applied to the source, this creates an alternating flux in ´

the magnetic core. According to Faraday's law, this flux creates electromotive forces in the

the coils. The induced emf is proportional to the number of turns in ´

the coil and the flux rate of change. According to the ratio of the number of revolutions between the

primary and the secondary, the secondary supplies the load with a voltage different from ´

that of the source.

Ideal transformer ´

If we take the coil of Figure 8.1, we define an ideal transformer having the ´

following features: ´

1. The resistance in the wires (at the primary and secondary) is zero. ´

2. The magnetic core is perfect ( ´ µr = ∞, ρ = 0).

If we study the implications of these simplifications, we see that the reluctance of the kernel

will be zero, and therefore there is no leak. The flow is therefore totally contained inside the ´

core. The magnetic coupling between the primary and the secondary is perfect; all the flow

The transformer makes it possible to transfer energy (in alternating form) from a

source has a load, while changing the voltage value. The voltage can be either ˆ

raised or lowered depending on the intended use. The change from a voltage level ´ to a `

another is done by the effect of a magnetic field. ´

Among the applications of transformers, we note:

1. Electronics: ´

(a) low voltage power supply `

(b) impedance matching ´

2. Electrical engineering: ´

(a) voltage transformation for the transmission and distribution of electricity

(b) low voltage power supply (e.g. halogen lamps)

3. Measurement:

(a) current transformers ´

(b) potential transformers

There are two main types of transformers, the battleship type and the columnar type.

In the breastplate type, a magnetic circuit with three branches is used, and the windings

are around the central branch. In the columnar type, a magnetic circuit with two

columns is used.´

The transformer consists of two (or more) windings coupled on a core.

magnetic, as in Figure 8.1. The side of the source is called the primary, and has

N1 wire windings (turns). The side of the load is called the secondary and has N2

windings. The flux ϕ is the mutual flux. The “•” indicates the polarity of the voltages. By

convention, a current that enters a “•” indicates a positive flow

Note that there is no electrical connection between the primary and the ´

secondary. All coupling between the two windings is magnetic. ´

When an alternating voltage is applied to the source, this creates an alternating flux in ´

the magnetic core. According to Faraday's law, this flux creates electromotive forces in the

the coils. The induced emf is proportional to the number of turns in ´

the coil and the flux rate of change. According to the ratio of the number of revolutions between the

primary and the secondary, the secondary supplies the load with a voltage different from ´

that of the source.

Ideal transformer ´

If we take the coil of Figure 8.1, we define an ideal transformer having the ´

following features: ´

1. The resistance in the wires (at the primary and secondary) is zero. ´

2. The magnetic core is perfect ( ´ µr = ∞, ρ = 0).

If we study the implications of these simplifications, we see that the reluctance of the kernel

will be zero, and therefore there is no leak. The flow is therefore totally contained inside the ´

core. The magnetic coupling between the primary and the secondary is perfect; all the flow