Yaskawa DSD 406 - Manual (Page 62)

4 Maintenance
58 3/21/96
GREEN
DATA
entr
❏ Press the DATA/FCTN key to enter the "Data" level for function # 998. The
DATA Indicator is GREEN to indicate that this function is currently being
accessed. The SCDU prompts the user to press the ENTER key by
displaying:
OFF
DATA
998
The process for accessing the PCU diagnostics function is as follows:
❏ Use the ⇑
and
⇓
keys to select function # 998 from the function level. The
DATA Indicator is off during this step.
Armature current is circulated through the armature
circuit during parts of the PCU diagnostics function. The
PCU will reduce the field current to zero on motors with a
shunt field in order to minimize motor rotation. However,
a permanent magnet motor must have its shaft locked
mechanically prior to running the PCU diagnostics routine.
If the PCU detects significant motor voltage during the test,
the PCU diagnostics function will abort.
WARNING
The drive has built-in diagnostic routines that can be performed via the SCDU.
The PCU diagnostic routines are able to test for four failure modes. The first test
checks the integrity of the three line fuses. Assuming the three line fuses are all
OK, the PCU then performs a test for shorted SCRs/doubler packs. If this test
indicates no shorted SCRs/doublers, the PCU then verifies that less than 5% of
the value entered for “Rated Field Current” is attainable. The PCU then tests for
open SCRs by passing current through the forward bridge followed by the
reverse bridge, and finally checks polarity of voltage feedback. The result of the
test is displayed on the SCDU after the test completes. The SCDU will light
certain unique LED patterns on its display corresponding with the failure (see
displays in the procedure that follows). The Fault Codes F910, F911, F912, and
F917 will not appear on the SCDU if the Error Disposition List is programmed
so that they are not reported to the Fault List (see “Error Handling/Reporting” in
the Operation Section). Power
Conversion
Unit
Diagnostics
Power Conversion Unit Diagnostics