What does impedance mean for Transformers?

What does impedance mean for Transformers?

Impedance is the current limiting characteristic of a transformer and is expressed in percentage. This percentage represents the amount of normal rated primary voltage which must be applied to the transformer to produce full rated load current when the secondary winding is short circuited.

What is low impedance transformer?

A low impedance transformer will have higher short circuit fault currents on the secondary side of the transformer. Electrical equipment installed on the secondary side must have current withstand ratings higher than the available fault current. Then net result may be more expensive electrical equipment.

What is a current limiting transformer?

The current limiting transformer is used to limit the current on secondary side under the fault condition from the current limiting transformer we conclude that to limit the current we need to add the extra core in between the windings. Also we limit the short circuit below the rated current.

How does impedance affect fault current?

Fault currents are caused by very low impedance short circuits. When there is a short circuit the resistance becomes very small, and that means the current becomes very large. If the resistance was zero, then the calculated fault current would go to infinity.

What is the impedance ratio of a transformer?

Impedance matching audio transformers always give their impedance ratio value from one winding to another by the square of the their turns ratio. That is, their impedance ratio is equal to its turns ratio squared and also its primary to secondary voltage ratio squared as shown.

What is a high impedance transformer?

Osborne high impedance transformers are used to step-up, step-down and isolate voltages in single phase and three phase circuits. A properly designed high impedance transformer can be used an an equivalent to an isolation transformer connected in series with an inductor.