Three-Phase Delta Connection Flashcards
What is the phase relationship between line voltage and phase voltage in a delta system?
They are in phase.
What is the phase displacement between the three line voltages in a delta system?
120 degrees apart.
When an open corner test is conducted on a delta transformer secondary, what should the voltmeter read?
What will it read if it is connected wrong?
0 V;
It would read double the phase voltage.
Does line voltage still equal phase voltage in an unbalanced delta system?
Yes, it always will.
Which phasor is typically used for reference in the delta system?
VAB.
What makes a balanced delta system?
Equal phase currents with identical power factors.
When adding two phasors to get line current, what must generally be done?
The direction of one current should be reversed (- 180º) so both currents are leaving the same line;
For example: IA = IAB + IAC, where ICA would be obtained with I = V/Z.
In a balanced delta system, how is line current found?
IA = IAB • 31/2.
What is power factor in a delta circuit?
The time relationship between phase voltage and phase current.
In a balanced delta system, what is the time relationship between phase and line current?
Line current lags phase current by 30 degrees.
What is your best friend when impedances in a delta system are not equal?
Complex mode on your calculator.
What is a High-leg?
The high voltage from phase to neutral on a 4 wire delta system;
It is unuseable and generally between phase A (by code) and N.
How is the high leg found?
By the phasor addition of one phase voltage and half of the next one.
