In the case of the step up transformer, the primary voltage will be lower than the secondary voltage, meaning a greater primary current than the secondary component. Under ideal conditions the voltage and current change by the same factor for any transformer, which explains why the primary power value is equal to the secondary power value for each case in the above table. As one value decreases the other increases to keep at a constant equilibrium power level.
Transformers can be extremely efficient. However, a transformer will always output a slightly lower power than its input, as losses cannot be eliminated completely. There is some transformer impedance. To learn more about transformers please see hyperphysics. Fossil Fuels. Nuclear Fuels. Transformers are also used at several points in the power distribution systems, such as illustrated in Figure 2.
Power is sent long distances at high voltages, because less current is required for a given amount of power, and this means less line loss, as was discussed previously. Figure 1. The plug-in transformer has become increasingly familiar with the proliferation of electronic devices that operate on voltages other than common V AC.
Most are in the 3 to 12 V range. Figure 2. Transformers change voltages at several points in a power distribution system. Electric power is usually generated at greater than 10 kV, and transmitted long distances at voltages over kV—sometimes as great as kV—to limit energy losses.
Local power distribution to neighborhoods or industries goes through a substation and is sent short distances at voltages ranging from 5 to 13 kV. This is reduced to , , or V for safety at the individual user site. The two coils are called the primary and secondary coils.
In normal use, the input voltage is placed on the primary, and the secondary produces the transformed output voltage. Not only does the iron core trap the magnetic field created by the primary coil, its magnetization increases the field strength. Since the input voltage is AC, a time-varying magnetic flux is sent to the secondary, inducing its AC output voltage. Figure 3. A typical construction of a simple transformer has two coils wound on a ferromagnetic core that is laminated to minimize eddy currents.
The magnetic field created by the primary is mostly confined to and increased by the core, which transmits it to the secondary coil. Any change in current in the primary induces a current in the secondary. For the simple transformer shown in Figure 3, the output voltage V s depends almost entirely on the input voltage V p and the ratio of the number of loops in the primary and secondary coils.
The input primary voltage V p is also related to changing flux by. The reason for this is a little more subtle. Taking the ratio of these last two equations yields a useful relationship:. This is known as the transformer equation , and it simply states that the ratio of the secondary to primary voltages in a transformer equals the ratio of the number of loops in their coils.
Dynamos at power plants generate large currents but not a lot of voltage. This electricity is stepped up to high voltage for transmission over wires, as electricity travels more efficiently at high voltage. Later, the voltage is stepped down before it enters your home — once again using transformers.
Since the emergence of the first constant-potential transformers in , transformers have become essential for the transmission, distribution, and utilization of Alternating Current electrical energy in all applications of power.
At Power Temp Systems, we specialize in making innovative equipment that efficiently and safely distributes and utilizes power for any project.
As a transformer transforms the voltage on the input side to the voltage required by the device or equipment connected to the output, it inversely increases or decreases the current flow between the different voltage levels.
An electrical transformer exemplifies the law of conservation of energy that says energy can neither be created nor destroyed, only transformed! Electrical transformers, having no moving parts or highly sensitive essential components or materials, are by nature remarkably reliable and durable pieces of equipment. A well-designed, quality-built transformer can be expected to function continuously and trouble free for years under rated operating conditions.
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