[Goemon]

I need a little reassurance to give me the confidence to power up my VFD and spindle because I feel so unsure about what I have been told previously about the need to derate (or not) with this brand (and power) of VFD.

My spindle is a 7.5hp 24,000rpm 3 phase unit. The label states 18 amps s1 although an online vendor lists it as 20.5amps. My VFD is an eBay Huanyang 10hp unit that states "1ph or 3ph input" and is rated for 34amps (although it doesn't state if this is input or output).

I know it's fairly common to find VFDs with 1ph in / 3ph out with no need for derating for spindles of less than 5hp but I have only seen Chinese vendors claim 1ph input for their 7.5kw / 10hp VFDs and they conveniently leave out any info about the need for derating for 1ph input.

Has anyone here used a 7.5kw Huanyang VFD to power a 5.5kw spindle from 1ph 220v power? If so, did it work properly and are you able to tell me how many amps it draws to output the 19amp 3ph power needed to power the spindle?

If the claim about 1ph input on these VFDs is BS (as all VFDs can be run off 1ph with derating) do they require the same 2x derating as regular 3ph VFDs? I have seen various opinions on derating. Some say x 1.7 and others say you need a 15hp VFD for a 7.5hp spindle. Which is correct?

If derating is required for Huanyang VFDs, would I be safe using the 10hp VFD with my spindle if I limit the speed to 16,500 rpm which is where it reaches 5hp until I can purchase a 15hp VFD?

What problem is likely to occur from using a VFD that turned out to be insufficient for the spindle? I.e. Does it break the VFD or the spindle (or both)? Breaking a $250 VFD is one thing but it's a different level of risk for an $1800 spindle...

[ger21]

You need to limit the current, not the speed. RPM is dependent on the voltage.

My guess would be 34 amps output. Input is probably 50+ amps.

You shouldn't hurt the spindle unless you stall it. (or wire it wrong)

[Al_The_Man]

Induction motor RPM is dependent on frequency not voltage.
A VFD can be set for a current limit, if this is exceeded it will shut down.
Al.

[mactec54]

I need a little reassurance to give me the confidence to power up my VFD and spindle because I feel so unsure about what I have been told previously about the need to derate (or not) with this brand (and power) of VFD.

My spindle is a 7.5hp 24,000rpm 3 phase unit. The label states 18 amps s1 although an online vendor lists it as 20.5amps. My VFD is an eBay Huanyang 10hp unit that states "1ph or 3ph input" and is rated for 34amps (although it doesn't state if this is input or output).

I know it's fairly common to find VFDs with 1ph in / 3ph out with no need for derating for spindles of less than 5hp but I have only seen Chinese vendors claim 1ph input for their 7.5kw / 10hp VFDs and they conveniently leave out any info about the need for derating for 1ph input.

Has anyone here used a 7.5kw Huanyang VFD to power a 5.5kw spindle from 1ph 220v power? If so, did it work properly and are you able to tell me how many amps it draws to output the 19amp 3ph power needed to power the spindle?

If the claim about 1ph input on these VFDs is BS (as all VFDs can be run off 1ph with derating) do they require the same 2x derating as regular 3ph VFDs? I have seen various opinions on derating. Some say x 1.7 and others say you need a 15hp VFD for a 7.5hp spindle. Which is correct?

If derating is required for Huanyang VFDs, would I be safe using the 10hp VFD with my spindle if I limit the speed to 16,500 rpm which is where it reaches 5hp until I can purchase a 15hp VFD?

What problem is likely to occur from using a VFD that turned out to be insufficient for the spindle? I.e. Does it break the VFD or the spindle (or both)? Breaking a $250 VFD is one thing but it's a different level of risk for an $1800 spindle...

10Hp is a good idea, you will need a 65 Amp supply to run it successfully, that would be the norm for 220v single phase, with spending that much on a spindle, you would want to use a quality VFD drive and use a power filter also and a reactor also, this would give you a longer life for your spindle

You will have another problem with having the ceramic spindle Bearings, you will have to do some extra work to Ground the Rotor of your spindle, it's only release of voltage build up would be through the tool or when you touch the spindle

[Goemon]

You need to limit the current, not the speed. RPM is dependent on the voltage.

My guess would be 34 amps output. Input is probably 50+ amps.

You shouldn't hurt the spindle unless you stall it. (or wire it wrong)

I understand that the current is the important issue and not the speed. I just thought that the current increased as the speed goes up. According to the manufacturers chart, it's only 5.6kw at 24,000. It's 4.2kw at 18,000 and so on. This is the chart:

https://www.cncpd.com/wp-content/upl...1-090-S103.pdf

Perhaps I am not understanding how a VFD controls speed. I was assuming, because of the various charts PDS sent me, that on a spindle like this where the top speed is also the base speed, that running it at 200hz would draw half the power it would draw at 400hz.

Are you saying it will draw the full 5.6kw / 19amps at 220v regardless if it is running at 3,000, 6,000, 12,000 or 24,000 rpm? I.e. There is no "safe setting" or safe speed if the VFD turns out to be insufficient?

[ericks]

The power consumed will be mostly due to the amount of load....without any load the motor will still consume power, the amount depends on the motor.
Induction motor speed is controlled by both voltage and freq....if you keep voltage constant and only vary the freq then speed will change but you will have torque issues, ideally you want to maintain a proper VF ratio to get max torque from your motor...

[ger21]

It only draws the amount of current it needs to maintain the commanded rpm. With no load, it might only draw a few amps. The more torque required to maintain RPM, the more current it will draw. My 2.2Kw spindle running on a bench only draws about 1 amp, regardless of the rpm.

If the VFD can't supply the current the motor needs, then the VFD should fault, or shut down.
You specify the maximum motor current in the VFD parameters. If you have a 20 amps spindle, and you set the VFD to 10 amps, then you'll have half the power. But it won't change the RPM at all.

According to the manufacturers chart, it's only 5.6kw at 24,000. It's 4.2kw at 18,000 and so on.

Power = torque x rpm. As rpm drops, so does the power output.

[Goemon]

Guys.... I fully understand the relationship of hp, torque and power and that the load will impact the draw. This is not what I am asking about.

I just want to know if anyone here is using a 7.5kw huanyang VFD to run a 5.5kw spindle from a 1ph 220v outlet and if it works, or... if 2x derating is needed like on 3ph input VFDs.

If the advice I received last time was wrong and I have to go and buy a 15hp VFD then so be it but I would like to make the decision with accurate info if possible.

If there is a way I can set up the 7.5kw VFD to run my spindle safely at lower power then I would like to know that too. For this, I would need to know how many amps my spindle draws at each power increment. I can't tell from the posts if I should expect my spindle to draw the same 19amps at 4kw as it does at 5.5kw or if goes down in direct proportion just like other types of motors. Without any load, the other motors I have used draw less power when you reduce the speed which makes sense as reducing the speed is done by reducing the voltage without increasing the amps...

[Goemon]

This ebay listing gives me some comfort (even though it's for a different brand of Chinese VFD) because it shows the 1ph input amps vs the 3ph output amps:

https://www.ebay.com/itm/11KW-220V-V...AAAOSw44BYIE8i

Their 7.5kw model draws 49amps from 1ph in to output 33amps 3ph. This gives me some hope that the stated rated amps on Chinese VFDs is what they output (I.e. Something you can use to size it correctly for your spindle) and not what they draw.

If the ratios are in any way similar (they seem different on each VFD) then I would be drawing 29amps at 220v 1ph to output the 19amp 220v 3ph it states on my spindle's label.

I guess we'll see. If the worst case is that the VFD blows, I can live with that risk. If it doesn't run my spindle then I have no use for it anyway...

[ger21]

Set the motor current in the VFD to 18 amps, if that's what the motor says. If the VFD faults under load, then you'll need a bigger VFD. I don't think there's any formula to tell you for sure if what you have will work or not.

[mactec54]

This ebay listing gives me some comfort (even though it's for a different brand of Chinese VFD) because it shows the 1ph input amps vs the 3ph output amps:

https://www.ebay.com/itm/11KW-220V-V...AAAOSw44BYIE8i

Their 7.5kw model draws 49amps from 1ph in to output 33amps 3ph. This gives me some hope that the stated rated amps on Chinese VFDs is what they output (I.e. Something you can use to size it correctly for your spindle) and not what they draw.

If the ratios are in any way similar (they seem different on each VFD) then I would be drawing 29amps at 220v 1ph to output the 19amp 220v 3ph it states on my spindle's label.

I guess we'll see. If the worst case is that the VFD blows, I can live with that risk. If it doesn't run my spindle then I have no use for it anyway...

What you are wanting to do is not new, machining centers that run on single phase do this every day, one that I have 7.5Kw, and runs on single phase, there install requirement is 65A, you will need this to run your whole machine, you are not just running the Spindle, so your 240v supply needs to be a minimum of 65A, and you won't have any problems, doing what you want to do, don't worry about the derating to much, you may not even notice it at all, it will depend how hard you push your spindle, I have run at 150% without any problems, not many here would have any experience with running a large VFD on single phase, I have been doing it for more than 20 years, have never had a failure electrically or mechanically, because of using a single phase power supply, just make sure your supply is enough

[sparkness]

I'm assuming 85% efficient motor and a 90% efficient inverter and a power factor of 90% and 230V so here is the math that I used

7.5Hp= 7.5 *746= 5595 Watts
5595W * 85% efficiency=6582 Watts
6582W * 90% inverter efficiency=7314W
so at 230V thats 31.8A single phase input needed at full load

the 3 phase motor Amp requirements=
HP * 746 / V * EFF * PF * 1.73

7.5 *746 / 230 *.85 *.90 * 1.73 =18.4A 3 phase

so a 5.5Kw, 7.5Kw or a 11kw inverter will work as you need approximately 32Amp single phase minimum input and need a 20.5A 3 phase output


The ebay listing posted shows that it will fit the bill and then some

I got the table from hyuanyang aliexpress site they recomend 7.5kw

[Goemon]

I'm assuming 85% efficient motor and a 90% efficient inverter and a power factor of 90% and 230V so here is the math that I used

7.5Hp= 7.5 *746= 5595 Watts
5595W * 85% efficiency=6582 Watts
6582W * 90% inverter efficiency=7314W
so at 230V thats 31.8A single phase input needed at full load

the 3 phase motor Amp requirements=
HP * 746 / V * EFF * PF * 1.73

7.5 *746 / 230 *.85 *.90 * 1.73 =18.4A 3 phase

so a 5.5Kw, 7.5Kw or a 11kw inverter will work as you need approximately 32Amp single phase minimum input and need a 20.5A 3 phase output

The ebay listing posted shows that it will fit the bill and then some

Your math marries up well to what I have been told elsewhere which is good. I like confirming things with multiple data points and especially when they come with a logical explanation that makes sense to me.

Also, I opened up the VFD last night and found a label that actually had something resembling useful info too. It states 31a 220v 3ph output from 1ph input. They really should state that info in the listing (or at least on the outside of the casing) because people need to know if they need a 30amp or 50amp outlets etc to achieve their required current for their spindle. If used to it's limit, this thing needs to draw over 50amps 1ph to output 31 amps 3ph. You don't know how or if to derate without this info.

Not only is the listing info incomplete, it's innacurate too as it states "34 amps" which is neither the input or output.

Anyway, on paper it can do the job but.... with that said, I have seen enough reported issues with these units to be scepticle that at 7.5kw VFD can run a 7.5kw spindle. I am happy I went with the 7.5kw to run a 5.5kw spindle. The next size up is 11kw and there is quite a large price difference so hopefully the 7.5kw VFD will be enough.

I'll do what Ger21 suggested on setting the VFD limits to the 19amps stated on my spindles label. Hopefully this will keep it safe.

Long term, the plan is to buy a quality brand VFD but, I think I would have to go with a 15hp 3ph unit for that. I haven't seen any non-Chinese 1ph 7.5kw VFDs. I spent a fair amount of time searching. They don't seem to exist.

[mactec54]

I'm assuming 85% efficient motor and a 90% efficient inverter and a power factor of 90% and 230V so here is the math that I used

7.5Hp= 7.5 *746= 5595 Watts
5595W * 85% efficiency=6582 Watts
6582W * 90% inverter efficiency=7314W
so at 230V thats 31.8A single phase input needed at full load

the 3 phase motor Amp requirements=
HP * 746 / V * EFF * PF * 1.73

7.5 *746 / 230 *.85 *.90 * 1.73 =18.4A 3 phase

so a 5.5Kw, 7.5Kw or a 11kw inverter will work as you need approximately 32Amp single phase minimum input and need a 20.5A 3 phase output


The ebay listing posted shows that it will fit the bill and then some

I got the table from hyuanyang aliexpress site they recomend 7.5kw

Here is what the manufacture recommends for the input power for the 7.5Kw VFD 49A he wants to use, so he still needs at least 65 A for his whole machine, your numbers is way to low

[mactec54]

Your math marries up well to what I have been told elsewhere which is good. I like confirming things with multiple data points and especially when they come with a logical explanation that makes sense to me.

Also, I opened up the VFD last night and found a label that actually had something resembling useful info too. It states 31a 220v 3ph output from 1ph input. They really should state that info in the listing (or at least on the outside of the casing) because people need to know if they need a 30amp or 50amp outlets etc to achieve their required current for their spindle. If used to it's limit, this thing needs to draw over 50amps 1ph to output 31 amps 3ph. You don't know how or if to derate without this info.

Not only is the listing info incomplete, it's innacurate too as it states "34 amps" which is neither the input or output.

Anyway, on paper it can do the job but.... with that said, I have seen enough reported issues with these units to be scepticle that at 7.5kw VFD can run a 7.5kw spindle. I am happy I went with the 7.5kw to run a 5.5kw spindle. The next size up is 11kw and there is quite a large price difference so hopefully the 7.5kw VFD will be enough.

I'll do what Ger21 suggested on setting the VFD limits to the 19amps stated on my spindles label. Hopefully this will keep it safe.

Long term, the plan is to buy a quality brand VFD but, I think I would have to go with a 15hp 3ph unit for that. I haven't seen any non-Chinese 1ph 7.5kw VFDs. I spent a fair amount of time searching. They don't seem to exist.

The information in the listing is correct, this has very little to do with your spindle draw, it's being able to get the correct DC Bus Voltage to run the VFD Drive correctly, and you can not do this without the correct input power supply the VFD has to maintain the DC Bus Voltage, or it will Fault the DC Bus Voltage for 240 Volt supply is approximately 340v

When you buy your VFD it does not have to be rated for single phase, any 3Ph VFD drive can run on single phase supply, if you know how to wire them correctly

You should set the VFD Parameters to what ever your motor spec's are, you should not set any of the Parameter settings to less than your motor Spec's

If you have enough input power to the VFD, you will be able to run your spindle at it's max output

[sparkness]

I was stating what a 5.5kw motor and VFD draw based on single phase input at full load not the entire machine's needs

[mactec54]

I was stating what a 5.5kw motor and VFD draw based on single phase input at full load not the entire machine's needs

What you posted was still to low for the VFD being used

[sparkness]

nope, most vfd's are in 93-97% efficiency range at 50-100% load for this HP rating so I calculated at a conservative 90% for this example, the motor efficiency I used might be high

[Eldon_Joh]

nope, most vfd's are in 93-97% efficiency range at 50-100% load for this HP rating so I calculated at a conservative 90% for this example, the motor efficiency I used might be high

The efficiency level is fine but you are unaware, and Mactec should have pointed this out to you: the power factor of the single phase input rectifier is about 60%. not 90%.

Take 7500 watts at 240vac and you get 31.25 amps. this is what your watt meter at the panel will bill you for. the amps heating up the circuit breaker and causing it to trip are more on the order of 50-55.

[sparkness]

got it