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Additionally for service and preventive maintenance
Following additional tools are mandatory for cleaning:
− An ESD safe blower / ESD vacuum cleaner
(ABB Service Finland code 0006ESD /
MUNTZ 555-ESD-S-E).
How to detect a faulty thyristor
Thyristor problems can be noticed differently:
A fuse is blown
This is an indication that a strong overcurrent has happened due to one of the following reasons:
− A shorted thyristor.
− A malfunction of the control electronics, e.g. wrong firing pulses (no thyristor defective).
− An external short circuit at the output terminals of the thyristor power controller without sufficient load.
Output current measured by an oscilloscope
Connect an oscilloscope to the output and check for the proper current (e.g. phase angle control):
Fault Tracing Thyristors
3ADW000449R0101 DCT880 Service Manual e a
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