support.automation.siemens.com | Technical Forum | Friday, March 14, 2025 4:36:34 AM
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| 9/14/2010 9:06 PM | |
Joined: 2/20/2007 Last visit: 11/19/2024 Posts: 122 Rating:
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Hello, I am using 3rw44 for 347 A slip ring motor. The motor is operating as a pendulum shear in hot strip mill. The setting i have kept are 1) Starting mode;- Voltage ramp with current lim 2) Starting voltage;- 40% 3) Starting current:- 50 sec 4) Starting current: 300% During no load condition, motor is running smoothly, current rises to 300% and finally settles down to its no load current(100A). But during coupling with Gear box, current doesnt settle after reaching 300% but increases to 1000A for 1min.and finally trips on motor over temperature fault. Can any one tell what might be the cause of this fault???. I thought this might be some mechanical problem in gearbox. But gearbox is smooth enough to be rotated along with shaft of motorby hand. So please tell what is the problem behind this tripping??? Additionally, resistance connected in the rotor ckt gets heated tremendously. How to decrease the current flowing thru this resistance??? |
| 9/15/2010 10:06 AM | |
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Posts: 467 Rating:
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hello Ahmed, ....attached a description, how a slip-ring motor has to be started via Softstarter (= Sikostart). I assume, that the used resistance in the rotor circuit is not correct dimensioned to allow a proper startvia Softstarter, when the gear box is coupled. You will have to use a resistor with higher resistance. But that cannot be calculated, you have to find it out by some tests.
kind regards LesPaul Attachmentslipring.pdf (305 Downloads) |
