PHEP 23 Flashcards
What component allows transmission of electricity between insulated circuits?
Transformers
What winding that receives energy inductively?
Secondary Winding
What characteristics do transformer output power have compared to input?
Different voltage at same frequency
What type of AC machines are Transformers?
Static AC Machines
What is the relationship between current, voltage and turns of wire?
V_1 * I_1 = V_2 * I_2
V_1 / T_1 = V_2 / T_2
I_1 * T_1 = I_2 * T_2
What type of transformer has a higher voltage on the secondary winding?
Step-up Transformer
What type of transformer only has 1 physical winding?
Auto-transformer
What should never be done to the secondary of a potential transformer?
Short Circuited
How are the windings wound on core configuration transformers?
A section of primary and secondary windings are wound around each leg of the core.
What does current transformers do?
Steps amount of current down.
What is hysteresis
Frictions between molecules due to alternating current
How does current change between phase and line inside a Y-connected transformer?
Line Current = Phase Current
Street Lighting systems use what kinds of transformers?
Constant current transformers
What units do transformer ratings use?
VA, KVA, MVA
What is the purpose of a bushing?
Serve as entrances for main leads into a transformer
What is the purpose of a conservator
Preserve dielectric strength of transformer oil
What should never be done on current transformer secondaries?
Secondaries should never be opened before the device is disconnected from its power source
What losses are there in an energized transformer if there is no load on the secondary?
Iron losses
In a transformer what must exist between the primary and secondary to supply the required primary current to supply the transformer losses & load on the secondary?
Balanced Condition
