transformer 3 phase voltages Flashcards
A poly-phase electrical system having a 90° phase separation is the ? type.
4 phase
A 3-phase motor will deliver ? power to a machine as a single-phase motor of the same size.
1 1/2 greater
The earliest poly-phase systems adopted by the electrical industry in the United States is the ? system.
3 wire delta
Single-phase motors produce vibrations caused by a pulsing torque pattern.
true
The secondary windings of three substation transformers are banked in a delta. The potential across the windings is 2,400 volts. The output voltage from ? is ?
line to line / 2400 v
On wye systems, unlike transformer bushings are joined with jumpers, and lines are connected at points where the bushing leads are connected.
false
Converting a distribution system from delta to wye increases the capacity of the system by ?
73%
When current through the secondary windings of a wye connected transformer bank is 300 amperes, the current through the load lines will be ? .
300 a
The individual sine waves of a 3-phase system are ? out of step with each other
120
A 3-phase line requires ? of the conductive material that is required by a single-phase line to transmit the same power over a fixed distance at a given voltage.
75%
Transformers with single primary bushings may be installed on wye systems.
true
Two lines that have the same rotation will always phase together.
false
Doubling the voltage on a line reduces the current required to supply an equal amount of power by 50%.
true
A single-phase tap take off from a 12.47-kilovolt, 3-phase wye line has a line-to-neutral voltage of ?
7.2 kv
In a 3-phase system, the three voltages are of different magnitudes.
false
