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pump Y/D starter U=1.1 Un

11/27/2012 6:38 PM	Rate (0)
Oscar_83PL Silver Member Joined: 10/22/2008 Last visit: 12/23/2025 Posts: 378 Rating: (5)	Hello, I am looking for some help with problem during transition star to delta. First of all Iwould like to describe the system. There is a water pump 7.5kW connected Y/D start. The pump gives a pressure about 3 bars. I am sure the connection of motor - contactors is correct. When I used to start at the workshop with U=400 V supply the motor started no problem with setting 50ms (transition)/2sec (star). However when I want to start the motor in other company, during the Y/Dtrasition the MCP trips. I can start the motor directly from star, I can strat it directly from delta. It starts with settings 25ms/500ms. The supply voltage is 437V (if it is improtant) My question is if the supply votage can cause such problem or should I look the problem somwhere else?

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12/11/2012 11:33 AM	Rate (0)
PISCEAN 2010 Posts: 8092 Rating: (884)	What is rating of MCP? In another workshop, does the MCP trips in both the cases?, means when starting in Y & when starting in D.
PISCEAN 2010 Posts: 8092 Rating: (884)
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12/13/2012 12:27 PM	Rate (0)
Oscar_83PL Silver Member Joined: 10/22/2008 Last visit: 12/23/2025 Posts: 378 Rating: (5)	MCP is 22Amps setting. The fuuniest thing is that mcp does not trip if i start it directly in star nor delta. It only trips during transition from star to delta. The cabling is checked and all is doe with recomended wiring of phases by siemens. http://www.automatyka.siemens.pl/docs/docs_ia/Zestawy_rozruchowe_gwiazda_trojkat_dla_silnikow_pradu_zmiennego_1.pdf

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12/13/2012 12:43 PM	Rate (0)
PISCEAN 2010 Posts: 8092 Rating: (884)	Please increase the time in star. In star the motor should run for 15 seconds & then to switch over to delta. Set accordingly & then check.
PISCEAN 2010 Posts: 8092 Rating: (884)
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12/13/2012 9:18 PM	Rate (0)
poya_xp Posts: 167 Rating: (4)	Oscar_83PL MCP is 22Amps setting. The fuuniest thing is that mcp does not trip if i start it directly in star nor delta. It only trips during transition from star to delta. The cabling is checked and all is doe with recomended wiring of phases by siemens. Hi i think your MCP has problem.it is impossible that connect a 7.5 kw motor direct online by a 22amp MCP without trip.at least for this DOL you need 40amp MCP.you must replace your MCP. for Y/D 7.5 kw you need 32 Amp MCP i hope it help.let us know what you do
poya_xp Posts: 167 Rating: (4)
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