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Hello there.-
I have a 550W 3ph electric motor / pump and a VFD which is a 220VAC input to 220VDC which is connected to my motor, so my motor can start at a lower speed until reach 1,390 rpm, also I have a 12VDC to 230VAC pure sine 1000W inverter, my question is: If I use a car alternator that rotate at 5000rpm or so and generate 14.7VDC and probably 80amps can I connect the alternator to the inverter and power up my motor/pump? the alternator will be rotating by an external supply using two pulley's and a belt...
 
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the alternator will be rotating by an external supply using two pulley's and a belt...
My brain isn't working today.... So what is turning the alternator?
 
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  • #4
My brain isn't working today.... So what is turning the alternator?
No, your brain is really working and good, but I do answer you question, I have another large motor that have double shaft (one at the front and one at the back) installing a pulley from this motor I want to connect the alternator : Large motor->alternator ->Inverter ->VFD->motor pump ->water to the field.
Now, could you answer my initial question??
John
 
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  • #5
Hello there.-
I have a 550W 3ph electric motor / pump and a VFD which is a 220VAC input to 220VDC which is connected to my motor, so my motor can start at a lower speed until reach 1,390 rpm, also I have a 12VDC to 230VAC pure sine 1000W inverter, my question is: If I use a car alternator that rotate at 5000rpm or so and generate 14.7VDC and probably 80amps can I connect the alternator to the inverter and power up my motor/pump? the alternator will be rotating by an external supply using two pulley's and a belt...
My brain isn't working today.... So what is turning the alternator?
Your brain is working fine, the alternator is going to be running with another motor that have another shaft at the back side and runs all day so, this is the picture Large motor->alternator->Inverter->VFD->0.55W motor/pump-> water to the field.
However, the inverter seller show a guide where indicate that for a pump I required a 3000W inverter because (I just find out)
" * Appliances and tools with induction motors (marked with * in the table) may require from 3 to 7 times the listed wattage when starting. The start-up load of the appliance or tool determines whether an inverter has the capability to power it. Be sure to check the specific wattage requirements and operating instructions for appliances / tools to be used. Please note: DC Amps listed in the table above is an estimate of the DC current draw from a 12V battery for that appliance. For 24V Inverters, the DC Amps from a 24V battery will be approximately half what is listed."
I don't want to use batteries apart that they are too expensive and have a short life.
Now, anyone can answer my initial question or is sufficient with the seller advice.
Thank you guys for your support.
John
 
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We need some more specifications of the motor and VFD.

In principal, it could work, but would be hugely inefficient.

Can you not just use the big motor to drive the pump through a belt, rather than have all the in between.
 

Pete999

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We need some more specifications of the motor and VFD.

In principal, it could work, but would be hugely inefficient.

Can you not just use the big motor to drive the pump through a belt, rather than have all the in between.
Or a flexible drive chain if you don't like using a belt, as in a M/A set up much more efficient that the set up you propose, not you Rob the OP.:):tongue:
 
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  • #8
We need some more specifications of the motor and VFD.

In principal, it could work, but would be hugely inefficient.

Can you not just use the big motor to drive the pump through a belt, rather than have all the in between.
Thanks Rob, at least you said it could work I think is a mater of trying to see if works what I am going to do is install the alternator to run at 5,000rpm so will give me 12 to 13VDC 80amps (constant speed) connect it to the 3,000/6,000W 12VDC input 220VAC output inverter and check the output it must be 220VAC and connect to my 0.75W VFD, the VFD works with 220VAC input and have an output of 220VDC then is connected to the 0.55W 3ph motor/pump, actually I connected the VFD to the motor and works fine and then I am going to let it run checking the output if maintain the constant volts and amps, I will let you know what happens.
 
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