Start-Up  09.02 
4-44  Siemens AG    6SE7087-6AK85-1AA0 
  Rectifier/Regenerating Unit    Operating Instructions 
You can select the "Circuit identification" function in the "Ready to switch on" status (009). 
 
Procedure:
 
⇓  P052 = 21  Select the "Circuit identification" function 
 
⇓  P key  The display appears: 
The rectifier/regenerating unit must be switched on within 20 s, otherwise fault 
message F091 (fault value 4) appears. 
 
⇓  Switch on the rectifier/regenerating unit. 
 
NOTE 
The firing pulses are enabled, the rectifier/regenerating unit carries current and the DC link is charged up to a 
certain limit! During circuit identification, the control angle is reduced until the generated separate current 
crests reach an average value (with reference to an averaging time of 1/6 of the supply cycle time) of 25% of 
P075 (with P160 = 150.0 %). By reducing P160 to 60.0 %, the required current crest size of up to 10 % of 
P075 can be reduced (with values P160 < 60.0 %, the threshold remains at 10 % of P075). Reduction of the 
size of the generated current crests may be necessary when the sum of the rated currents of the inverters 
connected to the rectifier/regenerating unit significantly drops below the rated current of the 
rectifier/regenerating unit. 
 
⇓  The operating display appears. Circuit identification takes about 10 s with a discharged DC link 
capacitor. The following parameters are set automatically: 
 
P140  Circuit resistance of the rectifier bridge 
P142  Circuit resistance of the regenerating bridge 
P143  Circuit inductance of the regenerating bridge  
P144  Capacitance of the DC link 
P310  Proportional gain of current controller 
P311  Integral-action time of current controller 
P313  Proportional gain of DC link voltage controller 
P772  Correction of measured values for thyristor voltage acquisition 
(parameters for special access) 
 
⇓  On completion of the function, "Ready to switch on" (009) appears in the display. 
 
NOTE 
If a fault message occurs during circuit identification, the cause of the fault must be eliminated and the function 
repeated (see Section 7.1). 
 
Circuit identification for 12-pulse mode must be carried out in succession on the 12-pulse master and on the 12-
pulse slave units (see Section 3.8.5). 
AoteWell Automation Sales Team
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