What is Step-up and also Step-down Transformers

This is a really useful device, indeed. With it, us can conveniently multiply or division voltage and current in AC circuits. Indeed, the transformer has actually made the long-distance infection of electric power a practical reality, together AC voltage have the right to be “stepped up” and current “stepped down” for reduced wire resistance power losses along power lines connecting generating stations with loads. In ~ either end (both the generator and at the loads), voltage levels are reduced by transformers for safer operation and also less expensive equipment.

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A transformer that boosts the voltage from main to secondary (more second winding transforms than major winding turns) is dubbed astep-uptransformer.

Conversely, a transformer designed to do just the the opposite is called astep-downtransformer.

Let’s re-examine a photograph presented in the vault section:

Figure 8.1 Transformer cross-section showing major and an additional windings is a couple of inches high (approximately 10 cm).

This is a step-down transformer, as evidenced by the high rotate count the the primary winding and also the low revolve count of the secondary. Together a step-down unit, this transformer switch high-voltage, low-current power right into low-voltage, high-current power. The larger-gauge wire provided in the an additional winding is necessary due to the boost in current. The main winding, which doesn’t need to conduct as lot current, may be make of smaller-gauge wire.

Reversibility of Transformer Operation

In situation you were wondering, itispossible to operate either of this transformer varieties backward (powering the an additional winding with an AC resource and letting the major winding power a load) to execute the the contrary function: a step-up can function as a step-down and visa-Versa.

However, as we witnessed in the an initial section the this chapter, reliable operation that a transformer requires that the separation, personal, instance winding inductances be engineered for specific operating arrays of voltage and also current, so if a transformer is to be used “backward” choose this it have to be employed within the original architecture parameters that voltage and current for each winding, lest it prove to it is in inefficient (or lest it bedamagedby excessive voltage or current!).

Transformer construction Labels

Transformers room often constructed in together a means that that is not apparent which wires cause the primary winding and also which result in the secondary. One convention provided in the electric power market to assist alleviate confusion is the use of “H” designations for the higher-voltage winding (the primary winding in a step-down unit; the an additional winding in a step-up) and also “X” designations because that the lower-voltage winding. Therefore, a straightforward power transformer will have wires labeled “H1”, “H2”, “X1”, and also “X2”. That is usually significant to the numbering of the wires (H1versus H2, etc.), i beg your pardon we’ll explore a little later in this chapter.

Practical significance of Step-Up and Step-Down Transformers

The truth that voltage and current gain “stepped” in opposite directions (one up, the other down) renders perfect sense once you remind that power is same to voltage times current, and also realize that transformers cannotproducepower, only convert it. Any machine that could output an ext power than it soaked up would violate theLaw of energy Conservationin physics, specific that power cannot be created or destroyed, only converted. As with the very first transformer example we looked at, strength transfer performance is very good from the main to the second sides that the device.

The useful significance that this is made more apparent as soon as an different is considered: before the arrival of reliable transformers, voltage/current level conversion could only be accomplished through the use of motor/generator sets. A illustration of a motor/generator set reveals the basic principle involved: (Figure below)

Figure 8.2 motor generator illustrates the simple principle that the transformer.

In together a machine, a motor is mechanically coupled to a generator, the generator designed to develop the desired levels that voltage and also current in ~ the rotating speed of the motor. If both motors and generators are reasonably efficient devices, the use of both in this fashion compounds their inefficiencies so that the as whole efficiency is in the range of 90% or less. Furthermore, because motor/generator sets obviously require relocating parts, mechanical wear and also balance are factors influencing both organization life and performance. Transformers, on the various other hand, are able to convert levels of AC voltage and also current at very high efficiencies through no moving parts, making possible the extensive distribution and use of electric power we take because that granted.

In all fairness, it have to be listed that motor/generator sets have not necessarily been obsoleted by transformers forallapplications. When transformers are plainly superior over motor/generator set forAC voltageand current level conversion, castle cannot transform one frequency the AC power to another, or (by themselves) transform DC to AC or visa-versa. Motor/generator sets have the right to do every these things with loved one simplicity, albeit with the limitations of efficiency and mechanical factors already described.

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Motor/generator sets likewise have the distinct property of kinetic energy storage: the is, if the motor’s strength supply is momentarily interrupted for any reason, that angular momentum (the inertia of that rotating mass) will keep rotation of the generator because that a quick duration, for this reason isolating any type of loads it is provided by the generator native “glitches” in the main power system.

Analysis of Step-up and also Step-down Transformer Operation

The winding with much more inductance have a greater voltage and also less existing than the other. Since the two inductors room wound roughly the exact same core product in the transformer (for the most effective magnetic coupling between the two), the parameters affect inductance because that the two coils space equal except for the number of turns in every coil. If us take one more look in ~ our inductance formula, we view that inductance is proportional to the squareof the variety of coil turns: