# NCEES Practice Exam #12

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#### Gman

##### Member
Why is the zero-sequence current phasor equal in magnitude and displaced by 120 degree? Shouldn't it be same as zero-sequence for voltage phasors which are same in magnitude and in phase? Thank you in advance

EDIT: See below. I actually had the corrected version so I may have misled the OP.

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The answer key says A,B,D so that's wrong right? A is incorrect but B and D are?
It's an incorrect statement, therefore not one of the correct answer choices.

View attachment 21490
The answer key says A,B,D so that's wrong right? A is incorrect but B and D are?
Yes. NCEES released an errata clarifying and correcting this (and I think 3 other problems).

Zero-sequence phasors have the same magnitude and same phase angle. There is no angular displacement between the zero-sequence phasors.

Positive-sequence phasors have the same magnitude, but 120-degree angular displacement rotating in the direction of ABC.

Negative-sequence phasors have the same magnitude, but 120-degree angular displacement rotating in the direction of ACB (or CBA).

Check the errata, or click on "PREVIEW" of the book when you log into your NCEES account. This was a mistake that has since been corrected in newer versions of the NCEES CBT Power PE Practice Exam:

account.ncees.org > Exam Prep > PE > PE Electrical and Computer: Power Practice Exam > View Product > Preview this book now

The answer was changed to just A and B since C is incorrect.

Zero sequence phasors are all equal in magnitude but have a zero-degree displacement angle between phases since the angle of each zero-sequence phasor is the same.

Edit - Beatin by @akyip!

Check the errata, or click on "PREVIEW" of the book when you log into your NCEES account. This was a mistake that has since been corrected in newer versions of the NCEES CBT Power PE Practice Exam:

account.ncees.org > Exam Prep > PE > PE Electrical and Computer: Power Practice Exam > View Product > Preview this book now

The answer was changed to just A and B since C is incorrect.

Zero sequence phasors are all equal in magnitude but have a zero-degree displacement angle between phases since the angle of each zero-sequence phasor is the same.

Edit - Beatin by @akyip!
Why A is correct? and why E is incorrect?

Why A is correct? and why E is incorrect?
The errata revised the multiple choices so A is the The Three Positive sequence Voltage phasors instead of the Zero Sequence current phasors, making the solution description correct.

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