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| VFD modeling ETAP https://brainfiller.com/arcflashforum/viewtopic.php?f=23&t=5429 |
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| Author: | PJ [ Sat Mar 20, 2021 8:19 am ] |
| Post subject: | VFD modeling ETAP |
I’m modeling a 200HP output VFD feeding a 200HP pump motor. The ratings from the cut sheet for the VFD are (output max FLA 250A, 160kw, 200HP and input 211A, 175kva) when I input the ratings the load flow calculator fails the VFD but the manufacturer says that the vfd is properly rated for a 200HP motor. I must be doing something incorrect in my model. Does anyone know what I might be doing wrong or any suggestions? Any help would be greatly appreciated. |
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| Author: | JBD [ Mon Mar 22, 2021 11:14 am ] |
| Post subject: | Re: VFD modeling ETAP |
PJ wrote: I’m modeling a 200HP output VFD feeding a 200HP pump motor. The ratings from the cut sheet for the VFD are (output max FLA 250A, 160kw, 200HP and input 211A, 175kva) when I input the ratings the load flow calculator fails the VFD but the manufacturer says that the vfd is properly rated for a 200HP motor. I must be doing something incorrect in my model. Does anyone know what I might be doing wrong or any suggestions? Any help would be greatly appreciated. How can your output current be greater than your maximum input current? |
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| Author: | DavidChief [ Tue Mar 23, 2021 7:08 am ] |
| Post subject: | Re: VFD modeling ETAP |
JBD wrote: How can your output current be greater than your maximum input current? VFD's typically rectify AC to DC, charge large capacitor banks to peak voltage and the use PWM or some version of such to convert back to variable frequency, variable voltage AC thus the output current can be substantially larger if the output voltage to the motor is lower until the charge on the capacitors is drawn down. |
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