Thyristor Diagnostics - Siemens SINAMICS DCM Operating Instructions Manual

Descriptions of functions
10.30 Diagnostics
10.30.3

Thyristor diagnostics

SINAMICS DCM can perform a self-test of its own power unit. As a consequence, defective
thyristors and other faults can be detected in the power unit.
Thyristor diagnostics cannot be used when SINAMICS DCM are connected in parallel and
connected in series.
Selecting thyristor diagnostics:
Thyristor diagnostics are performed during the switch-on procedure. Parameter p50830 can
be used to select for which switch-on procedures thyristor diagnostics is performed.
p50830
Thyristor diagnostics sequence:
At each switch-on procedure, starting from operating state o7 the drive goes into state o0.
During thyristor diagnostics, it remains in operating state o3 (see parameter r50000).
Thyristor diagnostics takes approx. 30 s.
Thyristor diagnostics comprises 2 parts:
1. Checking the thyristor for its blocking capability
2. Checking that the thyristors can be triggered
Faults that are detected result in fault message F60061. The fault value provides information
as to which thyristor was detected to be defective and what the possible cause of the fault
could be.
484
= 0 never
= 1 at the first ON after switching-on the electronics
= 2 at each ON
= 3 at the next ON (p50830 is then reset to 0)
All thyristors are individually fired and it is not permissible that current flows. Otherwise, a
thyristor has failed (internally broken-down), triggers with forward breakover or there is a
ground fault (i.e. connection 1C or 1D connected with ground).
Notice:
For IT line supplies (i.e. for line supplies with an ungrounded neutral point of the supply
transformer), the thyristor diagnostics cannot detect a single-pole ground fault. For these
types of line supply, it is recommended that a ground fault monitor is used.
All of the thyristors are triggered in pairs and in this case, a current must flow (as a
minimum, 5 % of r50072[1]). Otherwise, a thyristor cannot be triggered. This can also be
caused by a fault in the firing pulse generation.
Notice:
The low current that flows during this test can cause the motor to briefly rotate for motors
that are very easy to move and are not loaded, as in this operating state, the full field is
already present.
Operating Instructions, 1.2012, C98130-A7066-A1-05-7619
SINAMICS DCM DC Converter