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The transformer primary winding is connected to the alternating current supply. This causes a varying current in the primary winding, which creates a varying magnetic field in the transformer core. Because the primary voltage is alternating, the flux is also alternating - expanding and contracting, and changing polarity in time with the supply.

This alternating core flux 'cuts' the secondary winding/s of the transformer, and induces a voltage in the secondary coil/s. As long as there is a magnetic field that is moving, and a conductor for it to move across, it will induce a voltage in the conductor. While the actual induced voltage depends on the amount of flux, the amount of conductor material and the rate of change of the flux, the actual voltage can be calculated from:

Vsec = ((Vprim * Nsec) / Nprim)

where V = voltage, N = number of turns of wire in the coil, prim = primary and sec = secondary.

Transformers don't work on DC - they give a brief pulse out at switch-on and switch-off, because that's the only times the current is changing and the flux is moving. If you have to transform DC, you use a switching circuit that 'chops' the DC into a series of pulses that simulate AC as far as the 'moving flux' requirements of the transformer are concerned.

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13y ago
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12y ago

It's been my experience that most transformers (step down) are listed as primary:secondary. A 120v to 12 volt transformer will have a ratio of 10:1 (10 windings on the primary 120v side for every 1 winding on the 12 volt secondary side), for example.

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Q: Why transformer ratio is secondary winding voltage by primary winding voltage but not primary winding voltage by secondary winding voltage?
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Difference between input and output transformer?

The 'input' side of a transformer is called its 'primary' side, whereas the 'output' side is termed its 'secondary' side. The ratio of its secondary to primary voltage is equal to the ratio of the number of turns in the secondary windings to the number of turns in the primary winding. So if, for example, a transformer's secondary winding has twice as many turns as its primary winding, then the secondary winding will produce twice the voltage applied to the primary winding.


Does a step-up transformer have a higher primary or secondary resistance?

It is a step up transformer since the secondary windings are greater than the primary. the turns ratio is (primary to secondary) 1:5, so the primary voltages is 1/5 of the secondary (5 volts).


Is the transformer's iron core called the primary?

No. the primary winding is called the primary; the secondary winding is called the secondary. These are both wrapped around the iron core of the transformer. The core helps magnetically link the primary and secondary, which causes the transformation of voltage and current from primary to secondary.


Why do you use Two Winding run and start winding in the single phase motor?

Any transformer uses a minimum of two windings to change the voltage value. The primary side of the transformer is usually connected to the existing voltage. The secondary side of the transformer is usually connected to the load, who's voltage could be higher or lower voltage than the primary voltage.If the secondary voltage is increased the transformer is known as a step up transformer and if the secondary voltage is decreased the transformer is known as a step down transformer.The transformer terminal markings for the primary are H1 and H2 on a single coil primary and H1 to H4 on a dual voltage primary winding. Like wise the secondary terminal markings are X1 and X2 on a single coil secondary and X1 to X4 on a dual voltage secondary winding.


What value for a transformer determines the amount of voltage that is stepped up or down?

For an ideal transformer, the voltage ratio is exactly the same as its turns ratio. So if, for example, there are twice as many turns on the secondary winding as there are on the primary winding, then the secondary voltage will be twice that of the primary and the transformer will be a 'step up' type.

Related questions

Is there more current in the primary or secondary winding of a transformer?

The terms, 'primary' and 'secondary', describe how a transformer is connected and his nothing to do with which is the lower- and higher-voltage winding.The primary winding is the winding connected to the supply, while the secondary winding is the winding connected to the load. So, for astep-up transformer, the secondary winding is the higher voltage winding, whereas for a step-down transformer, the secondary winding is the lower voltage winding.For a loaded transformer, i.e. a transformer whose secondary is supplying a load, the higher-voltage winding carries the smaller current, while the lower-voltage winding carries the higher current.


What are the primary winding and secondary winding of a transformer?

The primary winding is the winding connected to the supply, while the secondary winding is the winding connected to the load. The terms, 'primary' and 'secondary' are unrelated to voltage levels.


How can you identify which one is step up or step down transformer?

A transformer has two windings, termed the 'primary winding' and the 'secondary winding'. The primary winding is the winding connected to the supply, while the secondary winding is connected to the load. The secondary voltage of a 'step up' transformer is higher than the primary voltage; the secondary voltage of a 'step down' transformer is lower than the primary voltage. The simplest way to determine whether a transformer is a step up or step down, is to measure the primary and secondary voltages. If you are simply looking at a transformer, then the transformer's insulated bushings will give you a clue -the higher voltage bushings are much bigger than the lower voltage bushings. If you have access to the inside of the transformer, then the higher voltage windings are thinner and have a greater number of turns than the lower-voltage winding.


What is the point of a step up transformer?

A 'step-up' transformer is a transformer with more turns on its secondary winding than on its primary winding. It's secondary (output) voltage is, therefore, higher than its primary (input) voltage.


What is stepup transformer?

A step-up transformer produces a voltage across its secondary winding which is higher than its primary winding. The secondary winding is connected to the load, while the primary winding is connected to the supply.


Difference between input and output transformer?

The 'input' side of a transformer is called its 'primary' side, whereas the 'output' side is termed its 'secondary' side. The ratio of its secondary to primary voltage is equal to the ratio of the number of turns in the secondary windings to the number of turns in the primary winding. So if, for example, a transformer's secondary winding has twice as many turns as its primary winding, then the secondary winding will produce twice the voltage applied to the primary winding.


What is the mutual coupling in single phase transformer?

primary winding flux links with secondary winding produses voltage across the secondary winding


What is the set up for a transformer that decreases the voltage on the out put side?

A basic, two-winding, transformer consists of two, separate, coils (called windings) wound around a laminated silicon-steel core. The winding connected to the supply (input) is called the primary winding, and the winding supplying the load is called the secondary winding. Alternating current flowing in the primary winding sets up an alternating magnetic field in the core which induces a voltage into the secondary winding. If there are fewer turns in the secondary winding, then the secondary voltage is lower than the primary voltage. If there are more turns in the secondary winding, then the secondary voltage is higher than the primary voltage.


Does a step-up transformer have a higher primary or secondary resistance?

It is a step up transformer since the secondary windings are greater than the primary. the turns ratio is (primary to secondary) 1:5, so the primary voltages is 1/5 of the secondary (5 volts).


What is high voltage side?

You are probably describing a transformer. The 'high voltage side' of a transformer is the winding with the greatest number of terms. It could be the primary or the secondary winding.


What is the function of the primary current when the secondary winding of the transformer is open?

When the secondary of a transformer is opened, there is no longer any load on the transformer. There will be some current flowing in the primary winding, which is needed to induce the voltage in the secondary. This primary current is referred to as the "no load" current, and is indicative of the core losses in the transformer.


Is the transformer's iron core called the primary?

No. the primary winding is called the primary; the secondary winding is called the secondary. These are both wrapped around the iron core of the transformer. The core helps magnetically link the primary and secondary, which causes the transformation of voltage and current from primary to secondary.