Beginner VFD questions, I want to do it right.

[Cheapo]

Thanks for all the info. I'm in the drill press so cheap that I wouldn't be upset spending $340 on my VFD install, especially if I get an auto-reversing tapping feature in the bargain.

If I can remote mount the display and E-stop button on the front of the drill head, it will be very clean and easy to operate.

I am cheap so I'm looking at the ammo can enclosure and the 10AWG VFD cable. I do know that 10AWG is smaller than 8AWG, it's also much cheaper. I haven't found 12AWG any cheaper so it seems like the right fit (I never turn away free copper). Inside the electric box on the Marathon motor, the wires look like 16AWG or at most 14AWG. It seems like wire nuts are the cheap and good system, I guess people use Wago to make things easy which is ok but I don't mind twisting on a wire nut...

For the 110v side, I will probably have 12AWG, possibly in an IEC cord to make it easy to replace.

I'm still not quite clear on how to do a braking resistor. Reading the manual I haven't found a part number or resistor specs yet.

As long as the cheap capacitive filter and cheap ferrite motor wire filter can fit in the ammo can, I think I'd like to incorporate them.

The filter used to avoid radiating noise back on to the 110v wiring seems more expensive. I would like one but it sounds like a piece I can skip probably.

I will call up Automation Direct with my questions on Monday probably.

 

[macardoso]

Thanks for all the info. I'm in the drill press so cheap that I wouldn't be upset spending $340 on my VFD install, especially if I get an auto-reversing tapping feature in the bargain.

If I can remote mount the display and E-stop button on the front of the drill head, it will be very clean and easy to operate.

I am cheap so I'm looking at the ammo can enclosure and the 10AWG VFD cable. I do know that 10AWG is smaller than 8AWG, it's also much cheaper. I haven't found 12AWG any cheaper so it seems like the right fit (I never turn away free copper). Inside the electric box on the Marathon motor, the wires look like 16AWG or at most 14AWG. It seems like wire nuts are the cheap and good system, I guess people use Wago to make things easy which is ok but I don't mind twisting on a wire nut...

For the 110v side, I will probably have 12AWG, possibly in an IEC cord to make it easy to replace.

I'm still not quite clear on how to do a braking resistor. Reading the manual I haven't found a part number or resistor specs yet.

As long as the cheap capacitive filter and cheap ferrite motor wire filter can fit in the ammo can, I think I'd like to incorporate them.

The filter used to avoid radiating noise back on to the 110v wiring seems more expensive. I would like one but it sounds like a piece I can skip probably.

I will call up Automation Direct with my questions on Monday probably.

Check out the VFD full manual (https://cdn.automationdirect.com/static/manuals/gs20m/gs20m.pdf) page A-18 or page 483 of the PDF. The drive has a built in IGBT to control braking so it only needs a passive braking resistor. There is a table to help you select the appropriate part number.

I'm not sure exactly what drive you selected from the GS20 family, but the braking resistor only adds $20 or less.

Beware that these can get quite hot and the wires emit significant EMI just like the motor output leads. Similar bonding and wire routing is recommended.

Table sizing is 10% duty cycle. Upsize the braking resistor if you think you need more than this (unlikely).

 

[macardoso]

As much as it would be nice to have a top notch VFD system with everything done per the manual, there is a practical and financial balance that needs to be factored in as well as benefit to risk. I have yet to see a factory installed VFD system on small lathes and mills use shielded cables, use RFI/EMI filters, use DC chokes, etc. A 4' motor cable, it is a point of diminishing return spending $100's for a shielded cable with grounding strain reliefs, proper pre-post VFD noise filters, etc. There is also the added complexity of knowing how to do these things correctly and have the proper tools, etc. A must do in an industrial environment, but a costly proposition for most hobbyist who are scrimping and get the cheapest VFD they can find. It is reasonable to use shielded cable for the low voltage control and speed pot, but more important as to the routing of the cables and proper grounding/enclosure. I do use shielded cables with star grounding on my builds, but as I mentioned I have yet to see it implemented on dozens of manual lathes/mills with the factory VFD installs. Getting into CNC, that is a totally different level and requires a higher level of electrical noise mitigation.

I typically recommend the best practices to everyone and let them decide where to cut corners. Even with experience, solving issues related to EMI is a total pain and can be a very frustrating experience for someone venturing into industrial controls for the first time and doesn't know best practices.

As an aside, I was quickly testing something for work on Friday and wired up a 270W motor to a basic VFD. Since this was a quick and dirty test to see if a parameter set worked, I skipped all the grounding and bonding. The cable to the motor was shielded but not grounded to the drive. As soon as I turned it on all my monitors started freaking out. The EMI even from this little motor and drive was enough to mess with my computer nearly 10' away.

 

[Cheapo]

Check out the VFD full manual (https://cdn.automationdirect.com/static/manuals/gs20m/gs20m.pdf) page A-18 or page 483 of the PDF. The drive has a built in IGBT to control braking so it only needs a passive braking resistor. There is a table to help you select the appropriate part number.

I'm not sure exactly what drive you selected from the GS20 family, but the braking resistor only adds $20 or less.

Beware that these can get quite hot and the wires emit significant EMI just like the motor output leads. Similar bonding and wire routing is recommended.

Table sizing is 10% duty cycle. Upsize the braking resistor if you think you need more than this (unlikely).

I'm only in to the 200s in the manual, it's not a terribly fun read. I forget the exact model number but it's the 110v in, 1hp 230v 3 phase out in a C form factor with a fan for forced cooling.

I think I'll try to get an 80mm or 92mm 110v case fan and a couple filter grills with a small mesh to try to keep the EMI in the ammo can and machining chips out. I could put the braking resistor in the air path and try to mount it so it doesn't conduct heat to the can.

Thanks for giving me the page number.

 

[macardoso]

I'm only in to the 200s in the manual, it's not a terribly fun read. I forget the exact model number but it's the 110v in, 1hp 230v 3 phase out in a C form factor with a fan for forced cooling.

I think I'll try to get an 80mm or 92mm 110v case fan and a couple filter grills with a small mesh to try to keep the EMI in the ammo can and machining chips out. I could put the braking resistor in the air path and try to mount it so it doesn't conduct heat to the can.

Thanks for giving me the page number.

Sounds good!

You can also place the braking resistor on the outside of the enclosure which helps considerably with heat

The manuals aren't fun to read. Once you've read a few different ones you'll know what to look for and won't need to read the whole thing