Closed-loop thyristor current control
5-58 System- and communication configuring D7-SYS - SIMADYN D
Edition 06.2002
• The discontinuous current limit should be determined.
The test mode should be set-up and the firing angle α should be
slowly reduced at PC6.AQL in the direction of rectifier operation.
Depending on the system constellation, the current should exit the
discontinuous range for a firing angle in the vicinity of 90° (PA6.YIT
≥1).
Document this firing angle as α
1
and the associated current actual
value (CAV.YC).
• To determine the upper current value, the firing angle α should be
entered with a short step. The angle should be very carefully (!)
decreased, as even small changes can result in significant current
changes. The firing angle for the step amplitude of the current should
be documented as α
2
.
• Change the firing angle as a step function from angle α
1
to α
2
and
trigger the oscilloscope when the current actual value changes.
T
0
1
0
1
T
Basic value
1st step
2nd step
[ms]
[ms]
Start
Fig. 5-31 Example: Circuit for the step combination
• The armature time constant should be determined from the current
actual value characteristic (refer to the Fig. “Determining the armature
time constant”).
5*TA = 0.9
Fig. 5-32 Determining the armature time constant (schematic)
Determining the
discontinuous limit
Determining the
armature time
constant
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