Did you know this when selecting a VFD for your motor?

[ltlvt]

Well I sure did not know this and therefore bought one capable of driving 2hp but now I realize mine only is good for 2.5 amps. My motor pulls 6 amps at full load. Good thing I found this out because I just bought a MSC mill with 3 hp motor and will be buying another VFD for it. Ignorance is very expensive at least my ignorance of VFD's has proven to be. Beware when someone tells you that you need one that is 1.5 times the motor HP. That is only a half truth. Hopes this video is helpful to others. If I had of watched it before buying the 2 VFD's I already have I would not need to buy the third one. LOL If my mistake helps someone else then there has been value to my mistake. I am sure I have and will continue to reap value from others mistakes and experiences in all areas of machining. Enjoy the video. It is my objective to give back to this forum when I can because I surely have received much from it.

 

[Shotgun]

How will you ever get 2Hp with only 2.5A? Even at 220V, you're going to need more than 3A to get 1Hp. To get 2Hp with only 2.5A, you're going to need to power it with something on the order of 600V.
If you look at the charts in the video, the factors he references only make a few percentage points of difference. Might make a difference if you're trying to spec out the cheapest VFD you can get my with in a manufacturing situation. For the typical hobbyist, unless your machine shop is halfway up Mt. Everest, and you plan to machine during a heat wave, with a need for the quietest motor in existence, I think most are well served by the 1.5xHp safety factor. You just have to buy from a reputable source that markets their Hp ratings at voltages that real people have.

 

[ltlvt]

Shotgun I am trying to get this right in my head. Are you telling me that if I have a VFD that is rated for 2 hp is automatically going to produce more than the 2.5 amps that I have referenced. I have the Hy040 023b Huanyang VFD. Some where I saw a chart that said it was rated at 2.5 amps. After watching Finno's video for the 6th or 7th time I see where you can set the amps at what the motor nameplate says which is 6 amps on my 2 hp motor. To do this I will set P 142 to 6 amps and see what happens. I will try this tomorrow and see what happens. As of now the digital display reads 2.5 amps and max RPM I can get by turning up the Hz to 60 is 720 Rpm. Also when reading the digital display on Hz the max that i am getting is 25 Hz. I will give it a shot tomorrow and report back to this thread. Your comment is very much appreciated.

 

[tq60]

This is a common thing.

Easy to avoid, though.

Follow a few steps.

Check motor plate. You need HP, volts, and amps.

Download the manual for the VFD, if you can't download the manual, do not buy.

In the manual there should be an application table showing motor ratings for both single and 3 phase input.

Find your motor in that table, then select the VFD that is indicated.

Next, READ THE REST OF THE MANUAL!

You need to be sure you understand how to install and operate it as well as any other information that may be there like remote control or options.

This helps you to insure you have a unit that meets your needs.

Sent from my SM-G781V using Tapatalk

 

[Shotgun]

Are you telling me that if I have a VFD that is rated for 2 hp is automatically going to produce more than the 2.5 amps that I have referenced.

Yessir. That is exactly what I'm telling you. It is math.
Volts x Amps = Watts
1Hp ~= 750Watts

Lots of reference material will give you these numbers. The exact wattage is something like 732. I just find 750 to be close enough and it allows me to do the math in my head.

220V x 2.5 Amps = 550W != 2Hp

 

[mksj]

Per the manual. You need to size the VFD to the motor operating current, plus any deratings. You do not need to oversize the VFD, so using a 7.5kW VFD to power a 2Hp motor is like using a shotgun to kill a fly. If using the HY VFD for a 6.5A motor you would use the HY01D523B VFD which has an output amp rating of 7.0A. Vevor is really at the bottom of the totem pole when it comes to VFD's. A real HY might sit just a little bit on top of that and there are now cheaper copies of the HY. Recommended VFD's for a mill 2 Hp single phase input that are simple to install would be:
Teco L510-202-H1-N https://dealerselectric.com/L510-202-H1-N.asp
Automation Direct GS11N-22P0 https://www.automationdirect.com/ad..._frequency_drives_(vfd)/micro_vfds/gs11n-22p0
Automation Direct GS21-22P0 https://www.automationdirect.com/ad...y_drives_(vfd)/general_purpose_vfds/gs21-22p0

3 Hp motor would be:
Teco, L510-203-H1-U https://dealerselectric.com/L510-203-H1-N.asp
Automation Direct GS11N-23P0 https://www.automationdirect.com/ad..._frequency_drives_(vfd)/micro_vfds/gs11n-23p0
Automation Direct GS21-23P0 https://www.automationdirect.com/ad...y_drives_(vfd)/general_purpose_vfds/gs21-23p0

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[rabler]

Horsepower has become so much marketing BS that it is meaningless. The simple answer is you need to read the full load amps spec off the motor, and be sure the VFD has the amp capacity that is at least that. Of course you also have to have a matching voltage. It gets more complicated when using a VFD designed for three phase input on single phase.

I see @mksj just posted the same point in more detail.

 

[Eddyde]

FTR, 1 hp = 745.7 watts. So yeah, 750w is a safe approximation for power supply requirements, though it doesn't include, inrush & overload current allowances, etc.

You may need to derate a VFD by ⅓ if using it for single phase output, as some manufactures state the HP rating at 3 phase input & output, even though it says it can handle single phase input. Thats why it's very important to check the detailed specifications.

 

[slodat]

The rated FLA of the motor is what matters. I have a 5hp Yaskawa spindle motor that is 30a FLA @ 5hp. This meant a 20hp Hitachi SJ-P1 VFD to run that spindle motor on single phase 240v supply. Hitachi has a single phase rating for these drives as do some other manufacturers.