If the transformer has two separate windings, then, YES a step-down can be used as a step-up, and vice-versa.
It is more correct to say you are reversing the high and low sides.
By definition Primary is the "IN" side and Secondary is the "OUT" side.
The Primary could be the high voltage side if it is a step-down,
or it could be the low voltage side, if it is a step-up.
Care must be taken when reversing the operation of a step-down transformer to insure that it does not exceed the ratings of the transformer. For example, let's say we have a 12 VA step-down transformer that takes 120Vac in and is rated to provide 12V at 1 amp at the secondary. If we were to reverse it and apply 12Vac to the new primary (the old secondary), we would have 120Vac at the new secondary, but to keep within the original ratings it could only be loaded to 0.1A @ 120Vac.
As long as you treat the output rating of the step-down transformer as the input rating as a step-up transformer, and don't try to draw current beyond what would normally have been applied to the high voltage primary, you should be fine. Potentially one could push up the voltage on such a transformer beyond what its stated application specified, while making sure not to exceed the power rating of the transformer and not exceeding the breakdown voltage of the transformer's insulation, for example driving the above transformer at 24V to get 0.05A @ 240Vac. It is important to realize though that the rated input voltage for a step-down transformer will likely not be a safe input voltage if you use it as a step-up transformer - for example, applying 120V to the above transformer with the windings reversed would generate 1.2KV!
One important point to remember when reversing a three-phase transformer to a step-up is what kind of windings it has. Most three-phase Transformers use a "delta" configuration on the primary side. This means that there are three "hot wires" and a ground, but not a neutral. (The white wire in a circuit). On the secondary side, transformers are usually wired up in a "Wye" (sometimes called a "star" configuration. Doing this allows the transformer to create a Neutral connection. If a step-down transformer is reversed to make it a step-up, the high (output) side will not have a Neutral connection. If one is not needed, say for a three-phase welding machine, this would not be a probem. However, if a Neutral IS needed ,say for lighting, reversing this transformer would not work. In this case, a listed step-up transformer will be needed. One final thing, if a step-down transformer is used as a step-up, a Neutral wire is not required to be connected to the input side.
A transformer used to step up or down the value of voltage.
'CT' is used to designate current transformers, and 'PT' is used to designate potential transformers. A current transformer provides a ratio of primary current to the secondary. A potential transformer provides a ratio of primary voltage to the secondary. A power transformer (step up or step down) resembles a PT more than a CT.
step up transformer
Transformers, step up or step down, use mutual induction in their operation.
the difference between a step up transformer and a step down transformer is that, in a tsep up transformer, the voltage secondary is greater than the primary side but in a step down transformer, the voltage secondary is lesser than the primary side
A transformer is used to step up or step down a Voltage supply.
A transformer used to step up or down the value of voltage.
If the voltage needs to be increased from a lower voltage to a higher voltage a step up transformer is used. If the voltage needs to be lowered from a higher voltage to a lower voltage a step down transformer is used.
transformers are used to step up or step down the voltages
A Transformer is a static device which is used to step up(or)step down the voltage in a transforming conductor
A transformer is a static device which is used to step up or step down the voltage in a powered circuit.
A step-up transformer increases voltage, while a step-down transformer decreases voltage.
A step-up transformer increases voltage, while a step-down transformer decreases voltage.
auto transformer is a one winding transformer which is are used for step up and step down voltage without chang its power and friquncy
'CT' is used to designate current transformers, and 'PT' is used to designate potential transformers. A current transformer provides a ratio of primary current to the secondary. A potential transformer provides a ratio of primary voltage to the secondary. A power transformer (step up or step down) resembles a PT more than a CT.
A step up transformer is used to step up an AC voltage
step up transformer