ABB PQFM Instruction Manual page 130

· CTs connected in open loop configuration
· Usage of an excessive CT ratio (including summation CTs). The CT ratio limit
is set at 20000/5.
- After acknowledging the error message, the CT values existing before the start
of the process will be restored and the automatic CT detection procedure will be
ended. The unsuccessful CT detection attempt is recorded in the event logging
window.
Conditions under which the automatic CT identification process may give unsatisfactory
results include:
- The use of CTs with extremely high ratio's (> 20000/5). This will result in an error
message indicating inconsistent CT positions. In this, the ratio of the summation
CTs that may be present should be included.
- The presence of a low impedance directly downstream of the filter connection
although the CTs have been correctly installed upstream of the filter connection.
This will result in wrong CT ratio's being found. In that case the commissioning
engineer can easily correct the CT ratio's found.
- The use of complex CT arrangements including summing CTs.
It is recommended that the results obtained with the automatic CT detection procedure
be crosschecked with a visual inspection of the installation.
7.9.2.3.2Manual set up of the CT positions and ratio's
For detecting the CT-settings manually, go to
130 The PQF-Manager user interface ç Manual Power Quality Filter PQFM