allen bradley 160s-aa04nsf1 help requested

I am wiring an Allen Bradley 160s-aa04nsf1 VFD to my 1967 Hardinge TM mill. My mill has the power cabinet on the lower right side which includes a fused disconnect, a motor starter, a 240V to 120V transformer to run the controls, and the switches to run fwd/rev and low/high speeds.

The Mill was originally wired for 3 phase input: . The main power cable from the plug has 4 wires: Black/Red/White/Green. The black/red/white were the original 3 phase power and the green is earth ground.

I want to use 240V single phase power and a VFD to power the motor. The black and red wires (hot wires) from the wall cord are wired to L1 and L3, respectively, and the white neutral is wired through the L2 connections. I'm wiring the motor for high speed operation; T1,T2,and T3 are connected together and the VFD will drive the motor T4, T5, and T6 wires. The motor also has a ground coming into the cabinet

I have questions about the 1 phase power going into the VFD and 3 phase power coming from the VFD.

Here is the manual for the VFD: https://literature.rockwellautomation.com/idc/groups/literature/documents/um/160-um009_-en-p.pdf

I'm confused by Fig 2.2 on page 2-3 and the discussion of motor cable types on page 2-6.

For Fig 2.2 - TB1, they reference a Ground screw and screws L2/L3 to be used for single phase power input. Since my VFD is a single phase 240V input, it does not have the L1 screw. Should I use my 240V Black/Red wires to connect to L2/L3 (respectively) and the White Neutral to go to the Ground Screw?

For Fig 2.2 - TB3, they reference the U, V, W going to the motor three phases (T6, T4, and T5, respectively). They also reference that the motor ground should go to the ground screw. Currently, my motor is grounded to the chassis at the motor itself and Earth grounded at the cabinet (Green wire) on the side of the mill. Should I run a chassis (GREEN wire) ground to the TB3 VFD ground?

I am worried about doing this for the manual alludes to, but does not state that the TB1 and TB2 grounds are connected internally, and then I would have my neutral directly connected to my chassis (earth, GREEN wire) ground.

Please let me know if I'm not including enough information in this ask or please ask any clarifying questions.

Thanks for your help.

Dave

For Fig 2.2 - TB1, they reference a Ground screw and screws L2/L3 to be used for single phase power input. Since my VFD is a single phase 240V input, it does not have the L1 screw. Should I use my 240V Black/Red wires to connect to L2/L3 (respectively) and the White Neutral to go to the Ground Screw?

Click to expand...

No; only ground should ever contact ground except once, in your main breaker panel or meter/disconnect.

Connect the red & black to the VFD, green to the ground connection on the VFD or a ground terminal block in the control cabinet, with a link to the VFD, and make safe/cap off the white.

In general all grounds must be connected together; the usual way of doing this is a big ground bar bolted to the chassis.

The exception is you want a ground wire between the motor and VFD, following the power cables as closely as possibly (ideally surrounding them; a screened cable or metallic conduit) to minimize inductance and provide a path for high-frequency noise to return to the drive.

Thanks, I have cross posted this in the Hardinge form and got the same advice. I did hook the VFD up with the neutral to the TB1 and the Earth Ground (green wire) to the TB2 and it ran. I'll remove the white wire from TB1 and run a ground to the chassis which is connected to earth ground.

I will still use the neutral. I have a 4x4 electrical box on the outside of the mill and have two duplex outlets in it. I have a 4 wire line from the electrical box on the wall. I have run the power from the L1 and L2 (which are the black and white wires) and the ground to the 120V - 4x4 box. I use this for my table feed and a light (mostly). I have a panel mount cylindrical fuse mounted in the box and have a 5 Amp fuse in it.



Here is the modified mill schematic. This schematic originally a PDF and I have limited software for making changes to the PDF. I connected the B, W, R to the L1, L2, and L3 (respectively) on the main power disconnect switch. I disconnected the control switches after the motor heater and ran the power to my VFD (L2 was White which originally went to my VFD ground) and L1 and L3 went to S and T on my VFD. I have since changed the ground wire to earth ground as shown in the schematic.

The VFD did work with the neutral on the TB1 ground and I have the controls/phase hooked up so that the potentiometer works correctly and the FWD/REV switch works correctly.

Is this what you are suggesting?

Dave

Things that are unsafe often still work... connecting that neutral to the neutral on your sockets is fine; don't connect it to ground.

I can't really read that diagram but it generally looks good.

Thanks for your explanation! I connected the ground wire to the VFD on the TB1 and TB2 and it is working fine.

I may have some electrical noise going back into my home power from the VFD. I have a X axis servo feed on my mill, and when I plug into the two duplex electrical sockets that are fed off of the power to the mill, the servo feed runs much faster when the motor starts on my mill. I measured the voltage at these sockets and they are at 120V before and during the motor running. I move my servo power feed to a separate socket on the wall and the increase in speed is not nearly as great, but it still occurs.

How do I fix this? Is my servo increase in speed due to noise from the VFD? Would I wrap my motor wires with a green ground wire and then ground it? Would you play with the VFD carrier frequency? It is running at 4 kHz now. Do you think adding a ferrite bead on the 4 conductor wire coming into the mill and a bead to the 120V duplex sockets would help the X axis servo keep a more consistent speed?

Dave

You probably have a good deal of noise coming out of the AC connections to the VFD. Most VFD do not have a filter on the line side (or the motor side).

There are plausible reasons why that might affect the feed motor controls, and you surely see the effect, so basically, yes that seems to be what is happening.

If you wanted to confirm it, find a portable AM radio and odds are that it will make a lot of noise if turned on between stations and brought close to the power wires with the VFD running the motor.

Your options are essentially various means of filtering those lines. A "bead" around the wires to the VFD might do something, if the noise is "common mode" noise, which it may be for several good reasons. I do not think it would cut the noise very much, honestly, the common mode noise from a VFD is relatively high amplitude, and tends not to be stopped by one bead.

A filter on the power line going to the VFD is probably a better choice, simply because the way they are made generally is more effective than even several beads. It will reduce noise to all loads on the nearby circuits, but the filters are not cheap, and need to be rated for the input current to the VFD.

You need to decide if the problem is worth the added cost.

techymechy said:

Thanks for your explanation! I connected the ground wire to the VFD on the TB1 and TB2 and it is working fine.

I may have some electrical noise going back into my home power from the VFD. I have a X axis servo feed on my mill, and when I plug into the two duplex electrical sockets that are fed off of the power to the mill, the servo feed runs much faster when the motor starts on my mill. I measured the voltage at these sockets and they are at 120V before and during the motor running. I move my servo power feed to a separate socket on the wall and the increase in speed is not nearly as great, but it still occurs.

How do I fix this? Is my servo increase in speed due to noise from the VFD? Would I wrap my motor wires with a green ground wire and then ground it? Would you play with the VFD carrier frequency? It is running at 4 kHz now. Do you think adding a ferrite bead on the 4 conductor wire coming into the mill and a bead to the 120V duplex sockets would help the X axis servo keep a more consistent speed?

Dave

Click to expand...

You have TWO PM threads running in parallel on the same machine & VFD.

That can get confusing. Best to kill-off the other one if you are done by now and into the usual VFD fiddle-f**king career.

You selected a VFD where others wudda run the mill off an ignorant dumb-as-a-box of Iron-and-Copper RPC, not HAD any of these "opportunities".

Playing with the VFD instead of making chips is why folks DO that.



Good on yah. It will be a "continuing education".

Thermite: Yes, I'll stop the other thread. I am fairly new to this PM forums and didn't note that there was a VFD specific forum until I started this thread.

As far as filtering: I'll take my portable AM radio out to the shop tonight. I have a scope that can calculate FFT's. Do you think if I run say 5 loops of 18 gage wire around the main power into the mill and connected a 1KOhm resistor between the loop ends that I can use my scope to measure the EMI spikes from the VFD? I could run a FFT on this signal and get an estimate for the frequencies with most of the EMI power.

As far as filters, are you referring to these passive devices:

TODAI 10A 120/240V AC NOISE FILTER 10-TNF-0202 | eBay

These seem reasonably effective for suppressing noise frequencies 1 MHz and above. It looks like the noise is sent to ground. Do you think that these could damage or make the VFD run erratically if the power is reflected back to the VFD?

Dave

I have found some more information on these passive filters. I was thinking about the TOKIN GF-210U (see pg 28 in the link):

https://www.tokin.com/english/product/pdf_dl/noisefilter_e.pdf

I am assuming that one wires the end with the ground lead to the VFD side and the two wire to the house side. Will this take care of a lot of the emitted EMI being fed back into my house?

Another question: Do I need to have a 3 phase filter between my VFD and my motor too? My Servo X axis drive is not operating correctly when my mill main motor is running. I'm pretty sure it is due to EMI. I want to fix this sooner than later.

And a third question: The motor on my mill has a high frequency hum. I can change the carrier frequency, but I'm not sure that this is a fix. Will the EMI filter be required because of this hum? I have a VFD on my lathe and I haven't had any issues with feedback to my house nor motor hum.

Thanks for your help.

Dave

FYI,

I adjusted my carrier frequency to 7kHz and the high pitch whine from my motor went away - at least I can't hear it now. I've read up that one does not want to have a filter between the motor and the VFD. The filter will reflect the high frequency power back to the VFD and may cause problems.

It occurred to me that I have a 120V isolation transformer with a filter that is used to control the conducted noise to hospital equipment. I tried placing the filter between my duplex socket on my mill and the X axis feed. The X axis feed works as intended with the filter. I really don't want a floor filter by my mill, so I bought a pretty good passive filter that I'll either place in my electrical cabinet or just outside of the 4"x4" box outside of the electrical cabinet. The filter will have 10dB attenuation starting at 50kHz and will have like 60dB attenuation at 1MHz and 80dB attenuation at 3.5MHz. My scope indicated that my peak noise spikes were at 1 MHz and 3.5 MHz. Hopefully this filter will fix my X axis speed control issue caused by conducted noise.

One last thing, the belt between my motor and countershaft is starting to fail. I called the Gates Engineering help line and they suggested that I get a Gates AX42 belt for this application. If this belt doesn't work, I might try a link belt for I really like those on my lathe.

Dave