## User Tag List

1. Senior Member
Join Date
Feb 2013
Location
India
Posts
2,555
Mentioned
0 Post(s)
Tagged
Originally Posted by Ingenieur
+(vab = 25 + 175j) or 175/82-(vac = 25 - 175j) or 175/-82-(vbc = 0 + 350j) or 350/90= 0 + 0jsomething does not computeone machine in reverse rotationmessed up connectionsetc or some combination
The generator voltage sequence is Vab, Vbc, Vca and their vector sum equals zero. But in your calculation Vac instead of Vca used. So perhaps reverse connection in one phase may also be a reason...

2. Senior Member
Join Date
Jan 2016
Location
Earth
Posts
6,049
Mentioned
0 Post(s)
Tagged
using abc
a 600/0
b 600/-15
c 600/15

ab = 20+155j = 156/82
bc = 0-310j = 310/-90
ca = -20+155j = 156/98
sum = 0

no real change
no idea what is going on

3. Senior Member
Join Date
Feb 2013
Location
India
Posts
2,555
Mentioned
0 Post(s)
Tagged
Originally Posted by Ingenieur
using abc
a 600/0
b 600/-15
c 600/15

ab = 20+155j = 156/82
bc = 0-310j = 310/-90
ca = -20+155j = 156/98
sum = 0

no real change
no idea what is going on
One solution to the part of the riddle is the generator is ungrounded and so phase to neutral voltage may be anything, around 590V in the OP case. Another is if the actual voltage readings of the OP are taken, I think their vector sum may not be zero and so there may be a break in windings or one phase winding may be reverse connected and that is my stand.

4. Senior Member
Join Date
Oct 2009
Location
Austin, TX, USA
Posts
10,465
Mentioned
0 Post(s)
Tagged
Originally Posted by JFletcher
I don't understand, if the neutral is kept floating, then aren't any line to neutral voltage readings meaningless?
No. Phase and neutral voltage to ground readings are meaningless.

5. Originally Posted by Ingenieur
using abc
a 600/0
b 600/-15
c 600/15

ab = 20+155j = 156/82
bc = 0-310j = 310/-90
ca = -20+155j = 156/98
sum = 0

no real change
no idea what is going on
The reason you can't make any sense of it is because the readings are meaningless on an ungrounded wye as others have stated over and over!

6. Senior Member
Join Date
Jan 2016
Location
Earth
Posts
6,049
Mentioned
0 Post(s)
Tagged
Originally Posted by ATSman
The reason you can't make any sense of it is because the readings are meaningless on an ungrounded wye as others have stated over and over!
you will get a reading thru capacative couple, because he DID get reading
regardless, ph-n will not be 3x ph-ph

7. The OP has left the discussion; so in other words it's all speculation after post #5.

8. Senior Member
Join Date
Jan 2016
Location
Earth
Posts
6,049
Mentioned
0 Post(s)
Tagged
we know a few things
only occuring on 1 bus
VLL = 150-300 (2 @ 150, 1 @ 300), VLN = 600, VLN ~ 2-4 x VLL
we know what the ph ang must be to result in these magnitudes

it is not cool for an op to make a post asking a question about an issue (especially an implausible one like this) and not providing feedback

9. Senior Member
Join Date
Apr 2009
Location
Williamsburg, VA
Posts
6,042
Mentioned
0 Post(s)
Tagged
Originally Posted by Ingenieur
we know a few things
only occuring on 1 bus
VLL = 150-300 (2 @ 150, 1 @ 300), VLN = 600, VLN ~ 2-4 x VLL
we know what the ph ang must be to result in these magnitudes

it is not cool for an op to make a post asking a question about an issue (especially an implausible one like this) and not providing feedback
That's been my main gripe with people posting questions on this form since its inception. People post the weirdest things, everyone brainstorms possible problems and solutions, and the o p rarely gets back to post what the problem was and how or if it was solved. C'est la vie...

10. Senior Member
Join Date
Oct 2009
Location
Austin, TX, USA
Posts
10,465
Mentioned
0 Post(s)
Tagged
Originally Posted by JFletcher
That's been my main gripe with people posting questions on this form since its inception. People post the weirdest things, everyone brainstorms possible problems and solutions, and the o p rarely gets back to post what the problem was and how or if it was solved. C'est la vie...
But we have a lot of fun speculating and arguing, don't we?

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•