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# How do you calculate transformer turns ratio given primary and secondary winding voltage?

###### Wiki User

###### 2009-06-05 19:21:03

Turns Ratio = (Primary turns / Secondary turns) To calculate the

turns ratio you have to actually know the number of turns or wraps

on the primary and secondary coils. Nobody knows that usually the

manufacture of the transformer doesn't even know. So what you can

use as and equivalent is to calculate the voltage ratio. So what

you typically need to look for is the Input voltage and divid it by

the output volatge. Usually that would be as follows; (Primary

Voltage/Secondary Voltage) = Voltage Ratio

## Related Questions

###### Asked in Electrical Engineering

### What is current voltage transformer?

A current transformer is a transformer that takes a ratio of
primary current, and delivers this ratio to the secondary. The
voltage across the primary will be insignificant, and the voltage
across the secondary is dependent upon the resistive burden put
across it (since the current is a constant ratio of the primary
current).
A voltage transformer is a transformer that takes a ratio of
primary voltage and steps this down to a specific secondary
voltage. Primary current is typically very small and secondary
voltage is typically very small.
A power transformer is a voltage transformer that is designed
for "large" primary and secondary currents.

###### Asked in Jobs & Education, Electronics Engineering, Electrical Engineering

### How do you calculate three phase transformer turns ratio?

By determining the transformer's primary and secondary
phase voltages. The ratio of the primary phase voltage to
the secondary phase voltage will be practically the same as its
turns ratio.
For example, in the case of a delta/star connected
transformer, the primary phase voltage will be its primary
line-to-line voltage; it's secondary phase voltage will be its
secondary line-to-neutral voltage.

###### Asked in Electrical Engineering, The Difference Between

### What is the difference between stepdown and stepup transformers?

A step-down transformer produces a secondary voltage that is
lower than its primary voltage, while a step-up transformer
produces a secondary voltage that is higher than its primary
voltage. The primary voltage is the voltage applied to the
transformer, whereas the secondary voltage is the voltage supplied
by the transformer. It's the transformer's turns ratio that
determines whether it is a step down or step up transformer: i.e.
the ratio between the primary and secondary windings. If there are
less turns on the secondary winding, then it's a step down
transformer; if there are more turns on the secondary winding, then
it's a step-up transformer.

###### Asked in Home Electricity, Electrical Engineering, Technology

### Why do you use two windings in single phase?

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.

###### Asked in Electronics Engineering, Electrical Engineering

### How many turns on secondary side of transformer with comparison to the primary side?

It depends on the type of transformer.
If it is a step up transformer the number of turns in secondary
side is higher than primary.
Stepdown means it will have fewer number of windings on the
secondary side turns when compared with the primary
side.
An isolation transformer has the same number of windings on the
primary as the secondary.
The ratio of the windings is proportional to the increase or
decrease in the secondary voltage. For example, twice the windings
doubles the voltage and 1/2 the windings halves the secondary
voltage. The isolation transformer is denoted as 1:1 and has the
same voltage on the secondary as the primary.
The ratio of secondary turns to primary turns is the same as the
ratio of secondary voltage to primary voltage.
e.g. if the secondary to primary turns ratio is 1/10, then the
secondary voltage will be one tenth of the primary voltage.

###### Asked in Home Electricity, Electronics Engineering, Electrical Engineering

### How should I calculate this. A single phase transformer is rated at 99kVA The primary voltage is 6.6kV and the secondary voltage is 220V Assume no losses and calculate The full load primary current?

First find the ratio of the transformer. 6600/220 volts. Second
find the secondary current, I = W/E, 99000/220. Third divide the
secondary current by the transformer ratio. The answer will be the
primary current. To check your answer (W (or VA) = V x A) multiply
the primary current times the primary voltage and the secondary
current times the secondary voltage and they should both equal the
transformer's kVA.

###### Asked in Electrical Engineering

### How can find the primary turns of the transformer knowing the primary voltage of the transformer?

The ratio of the primary voltage to the secondary voltage is
proportional to the ratio of windings. So if the primary voltage is
120 volts and the secondary is 240 volts there are twice as many
turns in the secondary.
Answer
As the previous answer says, you can work out the turns ratio of
a transformer, but knowing the primary and secondary voltages will
not help you determine how many turns are on each winding.

###### Asked in Physics, Industrial Engineering, Electrical Engineering

### What are step up and step down transformers?

A Step Up Transformer is one whose secondary voltage is greater
than its primary voltage. This kind of transformer "steps up" the
voltage applied to it.
The Step Up transformer is designed to increase the voltage from
the primary winding to the secondary winding.
A Step-Down transformer is one whose secondary voltage is less
than its primary voltage. The step down transformer is designed to
reduce the voltage from the primary winding to the secondary
winding. This kind of transformer "steps down" the voltage applied
to it.
The basic equation for stepping up or stepping down the
voltage
Np/Ns is known as the turns ratio.
The induced voltage in the secondary winding (Vs) is in
proportion to the primary voltage (Vp) and is given by the
ratio of the number of turns in the secondary (Ns) to the
number of turns in the primary (Np).
I to answer basic transformer questions.

###### Asked in Electrical Engineering

### How much is the secondry voltage vs with a primary voltage is vp equals 120v?

As far as a transformer is concerned, the secondary voltage Vs
value cannot be determined by the primary voltage Vp alone. For the
simplest of calculations the transformer primary-secondary turn
ratio must be known. For an ideal transformer ( and practicaly
ideal transformers don't exist as there will be various losses in
the transformer cores and windings), the simple equation relating
secondary voltage to primary voltage would be :
Vs/Vp=Ns/Np=Ip/Is
where Ns is the number of winding turns in the secondary of the
transformer, and Np the primary. Ip is the primary current and Is
the secondary.