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# What is the alternator phase current?

1. ## What is the alternator phase current?

A delta-connected three-phase alternator is driving a wye-connected resistive load. The alternator output voltage is 480 V. The load resistors are 12 ohms each. What is the phase current in the alternator?

The correct answer is not correct.  Reply With Quote

2. Originally Posted by wayneups A delta-connected three-phase alternator is driving a wye-connected resistive load. The alternator output voltage is 480 V. The load resistors are 12 ohms each. What is the phase current in the alternator?

The correct answer is not correct.
Agree with your assessment. My math:

Find phase voltage of Wye connected load => 480V/ sqrt(3) = 277.128 V

Find phase current of load => I = E/R = 277.128V / 12 ohm = 23.094 A

Find phase current of source => current of phase = current of line in wye connection => line current = 23.094A => current of phase in Delta = current of line / sqrt(3) = 23.094A / sqrt(3) = 13.33A  Reply With Quote

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Reputation  Originally Posted by kingRADi88 Agree with your assessment. My math:

Find phase voltage of Wye connected load => 480V/ sqrt(3) = 277.128 V

Find phase current of load => I = E/R = 277.128V / 12 ohm = 23.094 A

Find phase current of source => current of phase = current of line in wye connection => line current = 23.094A => current of phase in Delta = current of line / sqrt(3) = 23.094A / sqrt(3) = 13.33A
I calculated the same Amp values as above at first. Upon review i realized that the current calculation need to be done for the current circulating in the delta connected alternator and not the wye connected 3 phase load.
So no sqrt 3 conversion is necessary
add the 3 phase ohm values because they are all connected too the delta alternator.
12Ohms x 3= 36
480v line voltage divided by 36ohms = 13.33A is the phase current in the delta connected alternator.  Reply With Quote

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