Variable frequency drive into a motor then a screw - How to chk Power
Variable frequency drive into a motor then a screw - How to chk Power
(OP)
Hi
I am using a variable frequency drive to feed a motor which in turn rotates a screw.
Mains-> VFD(400V)-> Motor(400V,1380rpm)-> Gearbox-> Screw
The frequency range of the 400 volts inverter(VFD) is 0-65 Hz. The motor is also 400 volts and the current output from the inverter to the motor ranges from 2.1 to 1.4 A(according to the display). After about 20 Hz on the inverter the current remains constant at 1.4 A.
Being bad at electrics, I am a bit confused with regard to how much power will be required to move the screw. The screw will be used to convey material. Using the formula P=V.I.cos(phi), we have V for the motor but I remains same even when the the frequency and the screw speed increases.
I am thinking that the place that I need to check the current is
Mains-> VFD(400V)-> Motor(400V,1380rpm)->CHECK-> Gearbox-> Screw
instead of just reading the display from the inverter. A picture is also attached which hopefully will help.
Thanks
http: //files.en gineering. com/getfil e.aspx?fol der=71db8a 83-beab-40 a8-bf2e-5a 78ed6b09e6 &file= photo1.JPG
I am using a variable frequency drive to feed a motor which in turn rotates a screw.
Mains-> VFD(400V)-> Motor(400V,1380rpm)-> Gearbox-> Screw
The frequency range of the 400 volts inverter(VFD) is 0-65 Hz. The motor is also 400 volts and the current output from the inverter to the motor ranges from 2.1 to 1.4 A(according to the display). After about 20 Hz on the inverter the current remains constant at 1.4 A.
Being bad at electrics, I am a bit confused with regard to how much power will be required to move the screw. The screw will be used to convey material. Using the formula P=V.I.cos(phi), we have V for the motor but I remains same even when the the frequency and the screw speed increases.
I am thinking that the place that I need to check the current is
Mains-> VFD(400V)-> Motor(400V,1380rpm)->CHECK-> Gearbox-> Screw
instead of just reading the display from the inverter. A picture is also attached which hopefully will help.
Thanks
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RE: Variable frequency drive into a motor then a screw - How to chk Power
A final note: If you try to calculate power (which is a bad idea) do not forget the sqrt(3) factor.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...