Rockwell Automation 23P PowerFlex Digital DC Drive - Manual (Page 314)

314 Rockwell Automation Publication 20P-UM001K-EN-P - July 2014
Appendix C Application Notes
The Open SCR diagnostic test calculates the percentage deviation of current
feedback for each pair of SCRs from the average current feedback. The percent
deviation must exceed the value set for Par 216 [OpenSCR Threshold] before
the test proceeds to the next part of the diagnostic. In the next part, deviations
from the average current are accumulated over time to eliminate transient effects
from the calculation. When the deviations reach the value of Par 218
[OpenSCR Trip Lvl], an open SCR condition is annunciated based on Par 216
[OpenSCR Flt Cfg]. The open SCR(s) are indicated in Par 214
[SCR Diag Status]. By setting Par 215 [OpenSCR Warn Lvl], less than Par 218
[OpenSCR Trip Lvl], it is possible to get a warning that SCR operation is
imbalanced before a fault is generated. This warning is not an alarm condition
and is only indicated in Par 214 [SCR Diag Status], bit 13 “OpenSCR Warn.”
If you are experiencing nuisance open SCR events, you can use these parameters
to increase the tolerance to conditions that could trigger an open SCR fault (like
unbalanced AC supply lines).
Shorted SCR Test
Once enabled, the shorted SCR test executes each time the drive is started. This
introduces a delay of a few seconds before controlling the motor. If a shorted
SCR is detected, a non-configurable fault (F89 [Shorted SCR]) is generated and
also indicated in Par 214 [SCR Diag Status].