Transformer can be used to change high voltage to small one,but how to change a small voltage to high voltage?

Answer 1

"Backfeed" the transformer. The ratio of the voltages is proportional to the turns ratio of the transformer.

The utility transformers at a generating station typically step up the voltage from the generator to a transmission voltage.

Just be careful doing this. Applying 120 V ac to the low voltage windings of a transformer can produce very high (and lethal) voltages on the other windings.

This dangerous condition can exist after storms, hurricanes, tornados, and other major outages when customers hook up a portable generator without disconnecting their house from the utility's service. The 120 V output of the generator backfeeds the distribution transformer and produces high voltage on the utility wires. Depending on the turns ratio of the utility's transformer, it is very common for the resulting voltage to be in the range of 7,000 to 14,000 volts.

To put these numbers in perspective, the electric chair only requires about 2,000 volts.

Answer 2

A transformer steps the voltage up the same way it steps it down. From the primary bushing it goes into the transformers coils (windings) and comes out the x1 and x3 120v if you put 120 back through the x1 or x3 the voltage goes back through the windings and comes out the high voltage side whatever the transformer was built for example 2400v, 7200,7620,7960,14400,19920. There is customer on our system that we feed his meter 120/240 which feeds a transformer into the secondary side and then comes out the primary side 7960v underground to a transformer 3000 feet away then goes through a transformer and becomes 120/240 again. you do this because of the voltage loss on low voltage. higher the voltage the smaller the wire you need because you need less amps at high than at low.

Answer 3

You just put the small AC voltage into the secondary side of the transformer to get a higher voltage out the primary side, loosely speaking. It is the ratio of the turns on the primary side and the secondary side that change the voltage.

Some simple isolation transformers used on tube-style radios had a transformer that converted 120 VAC to 6VAC (handy because the tube filaments needed 6VAC). That 6 V was then connected into the secondary side of an identical transformer so that an isolated 120VAC came out of its primary. That made the chassis shock proof since there was no wired connection from the line to the chassis.

Answer 4

The same way. A transformer converts voltage directly proportional to the windings. If the primary has less windings than the secondary, the voltage will be stepped up.

Answer 5

Same way. If you have a transformer stepping down a voltage, reverse the transformer, and now it is stepping up the voltage. The give and take will be in current output. If you step up the voltage, you step down current by the same proportion.

V1 = Voltage at primary
V2 = Voltage at secondary
I1 = Current at primary
I2 = Current at secondary
N1 = impedance(or number of turns of wire) at primary
N2 = impedance(or number of turns of wire) at secondary

The equation that describes the relationship between current and voltage in a transformer is:

(V1/V2) = (I2/I1) = (N1/N2)

And,
Pout = Pin(ideal)
Pout = Pin - Plosses(real) losses are heat and stray flux

Answer 6

A transformer will step voltage up or step voltage down. It all depends on the turns ratio between the primary coils and the secondary coils.

Answer 7

It should also be noted that when you do use a transformer to step voltage up, you also decrease the current capability.

Answer 8

transformer can be stepped up as well stepped down depending upon the voltage you want to increase or decrease.
in this case use a stepped down transformer.