FSM AG
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13.09.2018
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Circuit Example
TSRD is separately fused with fast blowing types to protect the tyristors inside the TSRD, if the connection cables to and
from the TSRD are small and long enough. This is recommended if the output of the transformer can have a short circuit,
while start procdure. The fuses directly in front of the TSRD are selctive to the fuses on the input of the schematic drawing.
The transformer have to be softstarted in a no-load or low-load state. During the softstart only the no load current value is
flowing (at the delta vector group). Then can be softstarted a transformer with a higher value of current like TSRD has. The
TSRD only start the transformer then he activates the bypass contactor. This contactor is going in a self holding mode and
switches the TSRD off with his opener contacts. If any overload or Power line failures occures, the TSRD is not influenced
with overcurrents or wrong softstart repeating attempts, because he is switched off as long as the Bypasscontactor is
closed.
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Power line filters must be placed in front of the TSRD. In the other way the
phase angle cutting softstart procedure leads to high current peaks and can
disturb the power line or can destruct the thyristors. If capacitive AC- loads
are connected behind the transformer, a additional separation contactor must
switch on this loads after the softstart procedure. Also if other transformers
are connected on the output of the softstarted transformer must these be
separated with a additional separation contactor from the Softstart transfor-
mers output, while he is in Softstart procedure. If high valued capacitors are
placed after rectifiers behind the softstarted transformer, a special softstart
procedure can also soft start these capacitors. Look to the special order
numbers.
