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Vfd for an old 3hp lathe
- Thread starter Batmanacw
- Start date
After experiences with a cheap Chinese VFD and one from Automation Direct, I highly recommend Automation Direct. They will tell you that you don't need to oversize and both their instructions and their phone support are excellent. It's well worth a few extra bucks. Starting under load is nothing for a VFD. You can choose how long it takes to spin up to full speed. I set mine at either 0.5 second. That's a world different from "instant on."
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- Dec 9, 2021
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- 738
If you don't have 3 phase power, make sure the VFD is rated for your motor when run on single phase. Some VFD's are rated for less HP when run on single phase.
- Joined
- Jun 12, 2014
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- 5,053
You do not need to upsize your VFD, but you need to make sure your VFD can provide the 3 phase output current and maybe +10% of your motor FLA at the voltage and duty cycle of the machine/motor. Single phase input VFD's are common up to and including 3Hp running in what is typically heavy duty (constant torque mode). There are very few single phase input VFDs at 5Hp and above, and almost all are 3 phase input and require derating to run on single pahse. Things get a bit more murky when you look at VFD's Hp ratings/output amps and derating for running a 3 phae input VFD off of single phase. Almost all three phase input VFD's need to be derated by a factor of 2 or more to run on single phase, most require the use of a DC choke. Example below, is for the Hitachi SJ-P1 VFD's which are 3 phase input VFD's but can run off of single phase power if derated. A 3 Hp 3 phase motor is rated at 2.2kW and typically requires between 8-9.5A @208-230VAC. Based on the output current rating on single phase input power you would need either the 00330 (their 7.5Hp model) or their 00460 (10Hp model) to run off of single phase to run your 3Hp motor. Some VFD might also indicate a range of Hp say 5Hp for constant torque (machinery, ND or HD) and 7.5Hp for variable torque (fans and pumps, VLD, LD). Yaskawa's drives and many others are also the same, their 3 phase input VFD's require a derating 2-3X depending on the model and if a DC choke is used (see attached document). One needs to factor in all the deratings required for the specific VFD model under the operating conditions/load.
But for most single phase input VFD's, you are fine using a 3Hp VFD for a 3Hp motor. Most single phase VFD's also have a bit of headroom on the output amps, so match the motor Hp to VFD Hp. But always worthwhile to keep in mind that it is the output amps at the rated voltage that matters. CHeaper (generic) VFD brands people do tend to go to the next size up, as there ratings and reliability tend to be a bit over rated. I will also recommend the newer line GS20/GS21 VFD's from Automation Direct as being easier to install and offering a lot of VFD at the price point. I recommend them over the Teco L510 that are also commonly recommended. Hitachi WJ-200-022SF is also often used but probably not worth the extra $ for your application. Automation Direct also provides very good tech. support, I have installed a few of these drives and they have worked equivalent to the Hitachi WJ200. Choise of VFD also depends on the application and the VFD finctions required.
But for most single phase input VFD's, you are fine using a 3Hp VFD for a 3Hp motor. Most single phase VFD's also have a bit of headroom on the output amps, so match the motor Hp to VFD Hp. But always worthwhile to keep in mind that it is the output amps at the rated voltage that matters. CHeaper (generic) VFD brands people do tend to go to the next size up, as there ratings and reliability tend to be a bit over rated. I will also recommend the newer line GS20/GS21 VFD's from Automation Direct as being easier to install and offering a lot of VFD at the price point. I recommend them over the Teco L510 that are also commonly recommended. Hitachi WJ-200-022SF is also often used but probably not worth the extra $ for your application. Automation Direct also provides very good tech. support, I have installed a few of these drives and they have worked equivalent to the Hitachi WJ200. Choise of VFD also depends on the application and the VFD finctions required.
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- Jan 1, 2018
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- 1,329
I have a Fujitsu, a Teco, a few Hitachi and a HUANYANG VFD. The HUANYANG was by far the easiest to program and get running. I purchased a 10hp HUANYANG for my 7.5hp radial arm saw because it supported an external braking resistor and the 7.5hp HUANYANG VFD didn't. Since you program in the current and other motor parameters then run an auto config having an oversized VFD wasn't a problem. As a hobbyist having a machine down due to VFD problems isn't anything more than an inconvenience so my future VFD's will be HUANYANG. I can buy two HUANYANG VFD's for less than the price of a single Hitachi but there would definitely be lost production time swapping in a backup VFD... if I were a production shop.
It took me a good 5 hours to program my last Hitachi VFD. Then I tried to enable the external braking resistor after which the drive and my 13" SB lathe stopped working. I tried to restore the parameters through the Hitachi VFD configuration application but for some reason that I still don't understand I was unable to revert to the pre-external braking configuration. I went without my lathe for over a month before I worked up the energy to reprogram the Hitachi VFD from a factory reset which was again a 5 hour job.
Programming the HUANYANG 10hp VFD for my radial arm saw took about an hour AND the external braking resistor is working properly. The external braking resistor on my Hitachi driving my SB lathe still isn't working.
If you are a production shop I would definitely buy a Hitachi VFD from a reputable seller that will provide support when you have problems. If you are a hobbyist I would recommend the HUANYANG VFD. A Hitachi or similar top tier brand is a must if you want to integrate the VFD with a PLC or other advanced control setup but if all you want is basic functionality (1ph to 3ph, braking, speed control) a HUANYANG or similar Chinese VFD makes much more sense to me!
It took me a good 5 hours to program my last Hitachi VFD. Then I tried to enable the external braking resistor after which the drive and my 13" SB lathe stopped working. I tried to restore the parameters through the Hitachi VFD configuration application but for some reason that I still don't understand I was unable to revert to the pre-external braking configuration. I went without my lathe for over a month before I worked up the energy to reprogram the Hitachi VFD from a factory reset which was again a 5 hour job.
Programming the HUANYANG 10hp VFD for my radial arm saw took about an hour AND the external braking resistor is working properly. The external braking resistor on my Hitachi driving my SB lathe still isn't working.
If you are a production shop I would definitely buy a Hitachi VFD from a reputable seller that will provide support when you have problems. If you are a hobbyist I would recommend the HUANYANG VFD. A Hitachi or similar top tier brand is a must if you want to integrate the VFD with a PLC or other advanced control setup but if all you want is basic functionality (1ph to 3ph, braking, speed control) a HUANYANG or similar Chinese VFD makes much more sense to me!
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I am going cheap on the vfd. The lathe may not be a permanent fixture in the shop depending on condition. I can upgrade later. There are a host of $100 single to 3 phase vfds to choose from. The lathe fell into my lap. I'm not spending money on it until I know it's worth it.
The vfds I'm looking at is designed for running off single phase.
Found this one. In the listing it says to upsize for heavy loads so this is for 4hp.
Huanyang Vfd,Single to 3 Phase,Variable Frequency Drive,3Kw 4HP 220V Input AC 13 | eBay
220v 3kw 4HP VFD Specifications. There is enough space for cooling between each component, and the product casing is designed with multiple holes, the above features can make this VFD have a longer service life.
www.ebay.com