Transformers Flashcards
(19 cards)
Which machine permits the transfer of electrical energy between 2 circuits that are completely insulated from eachother.
Transformer
Which winding in a transformer receives energy inductively from the other.
The secondary winding
If the secondary winding has more turns than the primary what type of transformer is it?
It would be a step up transformer.
In transformers what must always exist between the primary and secondary fields to maintain the required primary current for the load and losses.
A balanced condition must exist between the windings.
The power transformer transfers electrical energy from one circuit at a certain frequency and voltage to a second circuit at the same frequency and a different voltage.
True
What type of ac machine are transformers classified as?
Static ac machine.
Transformers used to step current down are known as?
Current transformers.
What should never be done to the secondary terminals of a potential transformer?
They never be short circuited because a heavy current will flow,burning out the windings.
What type of transformer only has one winding?
Autotransformers.
What type of transformer only has one winding?
Autotransformers.
In a core type transformer, a section of the both windings are wound on each leg of the core, with the secondary winding wound next to the core and the primary winding wound over the secondary.
True.
What causes the heat in a transformer?
The hysteresis of the magnetic material or friction of the molecules.
Due to the alternating magnetic fields in a transformer, the iron losses occur when?
Whenever the primary is energized, even with no load.
How are transformers usually rated?
Classified as volt-amperes (va), in kilo-volt amps (kva), or mega-volt amps (mva).
Describe a conservator system on a transformer?
It acts as a barrier to prevent the atmosphere from contacting the oil in the main tank, preserving the dielectric strength.
How many types of main lead entrances are there for bushings.
4 types
Series street lighting systems require what type of transformer to function correctly.
They require a constant current transformer to supply a constant current source.
Describe generator and transformer windings connected in a wye setup.
Any two lines will be 1.732 times the phase voltage and the line current will be the same as the phase current.
When the primary is energized, the secondary of a potential transformer should never be shifted and the secondary of a current transformer should never be opened.
True
