Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations Toost on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Transformer Powering Reading

Status
Not open for further replies.

ougrad1999

Electrical
Sep 15, 2006
4
we powered up a 12.47kv/4.16kv, three phase, delta-wye XFMR and the follwing readings were taken:
A to B 4160
A to C 4160
B to C 4160

A to A 5kV
B to B 2.5KV
C to C 2.5KV

A to Gnd 2.4kV
B to Gnd 2.4kV
C to Gnd 2.4kV

what seem to be the problem? we've the doble and TTR testing before powering up, everthing seems fine.
 
Replies continue below

Recommended for you

Can you clarify what you mean by:

A to A 5kV
B to B 2.5KV
C to C 2.5KV
 
For instance, if you said:

A to B 4160
A to C 4160
B to C 4160

A to Grd 5kV
B to Grd 2.5KV
C to Grd 2.5KV

A to N 2.4kV
B to N 2.4kV
C to N 2.4kV

Then I would say that the neutral is not connected to ground.
 
Assuming that A to A is primary A to secondary A, you would expect 5260V on all phases if the primary source was solidly grounded and the secondary ground connection was at the same potential as the primary source ground.

If the primary source was impedance grounded, you would get a voltage difference between the secondary ground and the primary neutral point. This could explain the different voltages.
 
The secondary is Low Resistance Grounded at 200A, I suspected the electrical contractor connected the wrong phasing on the primary side.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor