[BanduraMaker]

So, I have a teknomotor spindle with a Hitachi WJ200 VFD and in conversations with the tekno rep, he was always pushing me to add a line reactor to the system saying that it will extend the longevity of the spindle by quite a bit and that just everything would be better. They don't distribute line reactors so I'm assuming he was being honest. A line reactor was only $100 so I picked one up.

Question is on the wiring and mounting. I currently have the thing bolted to my work bench and it is not grounded. There is no separate ground lug on the transformer.

Is this a disaster waiting to happen or am I ok with this setup? Do I need to make a grounded metal box for this and tie it to the chassis of the reactor or anything?

TIA,

[Al_The_Man]

I am assuming he recommended using it between VFD and motor?
You should bolt it to a grounded chassis or enclosure or run a ground wire to it if you are leaving it bolted to your bench, which doesn't sound very safe?
The ideal is close to the motor.
Al.

[BanduraMaker]

The upload photo thing wasn't working but here's a (lousy) picture of the setup.



I could shorten the run to the spindle by about 3' maximum. I could also throw a ground wire from the wirenut to the reactor without too much difficulty. Finding an enclosure would be a bit more difficult but possible.

[Al_The_Man]

The enclosure is up to how safe you feel, it does not affect the operation but your VFD and motor frame should have a ground conductor, the one you should have to the VFD would be closest to hook up to.
Al.

[BanduraMaker]

Yes, the motor and the VFD do indeed have a ground. You can see the green wire with the yellow wire nut next to the reactor - that comes from the 220 plug that feeds the VFD.

I'll probably enclose it at some point.

[mike_Kilroy]

I am assuming he recommended using it between VFD and motor?
Al.

I can't tell from the pix if it is between the motor and vfd or on the 3ph input to the vfd..... would be good to know which it is....

PS: wow, your website showing ur bandura's is neat!

[Al_The_Man]

I wondered, but when Andy mentioned shortening the run to the motor I assumed it was on the motor side.
Al.

[BanduraMaker]

Yes, I'm running single phase 220v into the VFD. VFD 3phase out goes to the line reactor then to the spindle. I highly doubt that the 3 feet of length I can get rid of between the reactor and the spindle is going to make much difference at all.

[mike_Kilroy]

good enough. yes, 3' less length out of like 13 total will make no difference to anything.

BTW, ur decision to add this inductor wasd good one; the spindle motor mfgr was 100% correct it will help cool ur spindle motor at any given load and it should extend the life of your motors insulation too. we use output reactors like this when we need to squeeze every ounce of power out of a given spindle motor. there is plenty of scope picture docs as well as temperature measurements that prove this helps - prob gets u another 8% power out the motor compared to same system w/o the output choke.

[BanduraMaker]

I ran a couple hour job today and the spindle was noticeably cooler. Not that it got super hot before but, I have a stick on thermometer on there and it barely got off the second temp after several hours of running.

I'm thinking it was $100 well spent.

[mike_Kilroy]

andy, please give us the rest of the data to complete the picture!!!!!!!!!!!!

when we generally use an output choke, we get about 8% more (maybe 8% cooler motor than w/o it) - but we start with a vfd that has probably 100% smoother output current than these small vfds like u used!!!

so how MUCH did it help on YOUR low cost wj200 vfd?? PLEASE give us the **BEFORE** temp from a similar job so we can the whole improvement!

[BanduraMaker]

Hi Mike,

I don't really have quantitative data on this but I do have a stick on thermometer on my spindle. When running a long job, my spindle temp sticker would start at around 40o C after 15 to 20 min and creep up from there hitting a maximum of around 50o C. Yesterday, It didn't make it past 45.

Mind you, I'm not really loading the spindle too hard though either - I think if I was more aggressive with my cuts, it would probably make a bigger difference.

[mike_Kilroy]

andy, tnx a LOT for the feedback!

keep in mind higher load should give similar PERCENTAGE improvement so ur data is GOOD!

hmmm..... 45 vs 50 sounds like 45/50= 10% cooler! I know, I know, I am stretching it here with the data at hand.... but my past experience said like 8% cooler on really clean output pwm drive.... u r saying maybe 10% cooler gut feel on Hitachi XJ200 not as clean drive..... maybe it is really 12 or 15% cooler if you duplicated really close - or not... but in any case, it is all coming together than that output choke prob got u 10-ish% cooler motor performance and maybe added another few hours insulation life to it (lets see, 3 hours every 4 days x 20,000 nominal hour life plus another 1000 hours - not much to take to the bank probably).... everyone knows that a few degrees cooler on a thing will increase its life SLIGHTLY; there are definitive studies that will show the exact life increase of insulation based on x degrees cooler running - not much if small! so bottom line seems to me is 2 fold:

1) adding inductor will increase ur motor life 0.00000001% or 20 minutes more out of 20,000 hour life design.
2) it WILL let u cut with 10% more HP than before!

Now which is more significant? Perhaps if u r still in contact with that mfgr u may want to relay ur experience back to them THIS way so they stop telling customers their spindle will last significantly longer if they put a choke on the output, but instead tell their customers they can get more torque out of it at a given cut!!!!!..............

I apologize for my excitement, but as an engineer in this field I get mighty upset with mfgrs who spout nonsense.

[Al_The_Man]

The other advantage that you are going to get, and probably what your supplier was referring to but it is not immediately detectable, is the effect of reducing the high frequency harmonics imposed on the motor, which can reach fairly high voltages, this is often the cause of motor failure, vector rated motors are meant to alleviate the risk of winding damage also, but I would hazard a guess that most induction motors of any quality use same winding insulation.
The inductive reactance of a choke increases with frequency, so that the lower operating frequencies pass through unsuppressed to a large degree. and the high frequencies fall under the effect of the higher inductive reactance.
Al.

[keebler303]

A related line reactor question:

I am in the process of hooking up a 25HP 460V VFD and motor. I am using a transformer to step up the available 230V to 460. Do I still want a line reactor on the line side of the VFD or does the transformer fill that role?

Thanks
Matt

[mike_Kilroy]

the xfmr fills that role

[Al_The_Man]

You may want to consider one on the motor side, the input choke is generally used where the supply transformer is some remote distance away and other machinery is fed from it.
Al.

[keebler303]

I plan to use one on the motor side as I'm not using an "inverter duty" motor. The transformer secondary goes straight to the drive with about 15-20ft of wire. The majority of the other loads are powered from the 230V prior to the transformer.

Thanks for the help
Matt