The AC transformer Flashcards
What is a transformer?
A transformer is an electrical device that uses electromagnetic induction to pass an alternating current signal from one electric circuit to another.
Why is it not possible to construct an ideal transformer in practice?
Because there are always power losses within the transformer itself.
What is a perfect or ideal transformer?
A perfect or ideal transformer is one whose output electrical power is equal to its input electrical power, so that no power is lost in the transformer itself.
What is transformer efficiency?
Transformer efficiency is the ratio of its output power to its input power.
Why are real transformers not perfect?
Real transformers have power losses that end up as heat, which must be removed from the transformer.
What are the types of transformer losses?
Copper losses
Hysteresis losses
Flux losses
Eddy current losses
What causes copper losses?
The resistance of the copper wire in the primary and secondary windings.
What causes eddy current losses?
The alternating current inducing a current in the core of the transformer.
What causes hysteresis losses?
Molecular friction in the ferromagnetic transformer cores caused by changes in the polarity of the applied current.
What is transformer rating in radiography?
The maximum combination of factors that a system can withstand without damage.
What can happen if a transformer operates beyond its designed maximum conditions?
It may cause damage to the electrical insulation of the winding by overheating or electrical breakdown.
What are the key factors included in transformer rating?
Maximum kVp which the secondary winding may produce (typically 125 kVp)
Maximum continuous current the transformer can supply
Maximum current supplied for short X-ray exposures
