230V single phase to 400V 3phase WYE

Hello Everyone,
I've been reading this forum for awhile, although never posted anything. A little background I've owned my own die/mold, cnc machine shop for 20 years. We're out here in the sticks so everything is running off phase converters. I have several cnc machines (2 haas,3 makino's 1 okk) all run on the phase converters. we use the Phase Perfect PT380 and have 3 of them. the haas machines run direct off the converters, the makino's and okk have a stepdown 230V/208V delta-delta transformers. They all have worked fine. We've purchased our 1st 5 axis, FPT Stinger 180. It runs on 400V WYE configuration. So we have the phase perfect running into a step-up 230V/400V Delta/WYE transformer. We have the H0 of the WYE side grounded through the system because the machine not only wants to see phase to phase voltage but even voltage phase to ground. The machine will run for about 15-20minutes then the inverters/drives will fault out. I've had power studies done by the local utility company and internally. We originally thought that it was a harmonic issue but we've add a unit from Environmental Potentials that take care of the high end harmonics but to no avail. The only thing so far that we did notice is that the voltage on the secondary WYE side of the transformer varies about 10V phase to phase. Phase to ground only varies about 1volt. The voltage on the primary delta side from the phase converter is pretty stable. If anyone has any thoughts it would be greatly appreciated.
Thanks,
RJ

Not at all familiar with the machine, and specs on line are minimal, even in the catalog. But power issues are similar...

The 10 V seems to be a reasonably low percentage of line volts. 10 volts phase-to-phase is only 2.5%, which is all you can expect from the powerco. The Phase Perfect regulates to 1%, supposedly, or 4V difference, and the transformer has some impedance, and some inherent variability that can add to that and get 10V.

A time delay problem like that is often a heat-related issue. Does the machine give an error code that relates to any particular condition? If so, what condition?

Does it give a range of acceptable line volts in the manual? Your 230-400V transformer will give 415V 3 phase with 240V input, . Possibly the machine does not like that, plus out in the sticks the power tends to be more variable. It may be sent out higher voltage closer to the substation with the idea that at the end of the line it is still above the lower limit.

A nominal 230V line can be up to 250V, and a nominal 240V line can be up to 264V, That will raise the output to the CNC by the same proportion. Could overheat something in the controls and make the unit fault.

What actual voltage have you seen out of the PP unit?

Really need to know what the drive fault is.

I'm a data guy. I would have a oscilloscope on it looking at the wave forms at time of trip and also a power quality monitor (at minimum all 3 phase voltages and power factor and preferably amps also). I would start there and see where it leads me.

One time I worked on a line that had a smallish AC servo drive hung off the same transformer as a larger (200 or 250 hp) DC drive. The DC drive failed and was replaced with a new Siemens DC drive. The servo drive kept tripping and and no one could figure it out. It was a German drive and no would could tell us concretely if it was tripping on under or overvoltage.

I have a very smart friend that owns a drive service company. I called him to help and solved it. The new Siemens drive had a different sized reactor in the drive than the old one. To try to solve the problem they added an additional isolation transformer. That was on top of 2 existing transformers in front of the distribution transformers. Our recommendation ended up to remove 2 transformers - they looked at us funny. It fixed the problem.

Where I was going with this story was that I was actually called in to mediate what harmonics solution they should be implementing. They were convinced it was a harmonics problem and 2 vendors had given them vastly different harmonics remediation solutions. It had nothing to do with harmonics. Proper troubleshooting fixed the problem.

230V Delta to 400V WYE

Thanks guys for the replies:
1)The machine error codes tell us that "inverter and supply module readiness is missing" and "power module not ready" There are a bunch of other unrelated codes so it's really wigging out. The controls are Heidenhain so I'm not familiar with the drives. I can tell you that Initially when we had this problem and I had the install people here we rented a diesel generator. Plugged the machine in at 400V WYE and it ran like a champ. We have done power studies on the incoming from the utility/primary side of the transformer (output of the phase perfect) / and secondary of the transformer. I will attach them along with some of the pictures of the alarms and possible causes per the error screen on the unit.
2)Manual says +/- 10%V but when I talk to the service tech it's +/- 3% which is pretty tight. The odd thing is the voltage fluctuation that I'm seeing on the primary side of the transformer is 233V phase to phase within 1.5V steady, so we have it set on tap#5 and it should be coming out 400V within +/-2.5V (1.5*1.71) On the secondary of the transformer it varies 10-12V(maybe even 15V) constantly moving no matter what 2 lines you pick. This is under a no load condition with the machine off.It could swing a matter of 10V within 1/4 of a second, and it's doing this constantly.
3)Getting back to the machine it will fault out no matter if it's running on something or just sitting there.Again thanks for the feedback and any other info that I could give just ask. (This is driving me crazy!)
Thanks,
RJ
P.S.Trying to attach the power logs but they seem too large.

The variations in voltage seem really odd. Especially if the same meter reads the input voltage to the transformer as steady.

There must be some more info here.... In general, transformers are very well behaved and put out what they are given.

I assume you have checked the connections on the pri and sec sides of the transformer.

Are the voltage changes the same if you have a 3 phase load on the secondary? (you may not have one other than the machine)

What is the meter you are using to read these voltages?

Pics of setup and data plates?

As a tie-breaker, I would suggest connecting several identical old fashioned 120 V light bulbs in series across one of the outputs (to make up a 400V load), and see if the brightness variation is confirming the meter readings of voltage variation. Two bulbs would do it if connected line to neutral.

At a guess, the controls are not liking the voltage changes, and may be faulting out because those changes get interpreted as different problems (high ripple current, phase imbalance, maybe even overcurrent). Voltage changes of that sort can in fact cause some of those conditions, and the key is likely to be getting it tamed down.

230V Delta to 400V WYE

Guys,
I've created a link to my dropbox with power quality logs and the error codes. Hope this helps.

Dropbox - Practical-Machinist - Simplify your life

Thanks,
RJ

auroracc said:

2)Manual says +/- 10%V but when I talk to the service tech it's +/- 3% which is pretty tight. The odd thing is the voltage fluctuation that I'm seeing on the primary side of the transformer is 233V phase to phase within 1.5V steady, so we have it set on tap#5 and it should be coming out 400V within +/-2.5V (1.5*1.71) On the secondary of the transformer it varies 10-12V(maybe even 15V) constantly moving no matter what 2 lines you pick. This is under a no load condition with the machine off.It could swing a matter of 10V within 1/4 of a second, and it's doing this constantly.

Thanks,
RJ

Click to expand...

After looking at the log graph's, it appears that the problem lies between the transformer wye secondary and the machine. Where were the probes placed during the logging of the wye side, at the machine terminals or the transformer terminals?

The 1Φ utility voltages look steady, as well as the phase converter delta voltages into the transformer primary.

On the wye output side looks to be the issue.
Phase A has 5 voltage drops of about 40V.
Phase B has hundreds of drops of 40V or more. And a maximum voltage swing of 109V for the week.
Phase C has zero noticeable voltage drops.

Interesting part of phase B, it that the voltage was near perfect, while the machine was unloaded for 2.5 days of the week.



I would investigate the connections on the load side of the transformer, to the machine controls for starters. This appears where the voltage issue is.

SAF Ω

The probes were placed at the transformer terminals not the machine. We will look at the load side of the transformer. Does anyone know if the "stinger leg" comming from the phase converter (208V to ground) could be causing an issue?
Thanks,
RJ

If you have a delta wye transformer, there should be no issues from the primary side if the delta voltages are steady.

There MIGHT BE some common-mode voltage coming through, but that would be spikes, not surges, I see that the error message suggest noise may be an issue, though...

The probe position may nit be an issue, the transformer has far more impedance than the wires do. Variations can occur on the transformer terminals if the load changes, as it would in case of a loose connection.

That said, a loose connection at the B phase wire would be expected to affect A-B and B-C, but only one phase pair showed big noise-type variations (V2-3).

I agree with what others are saying. I would Look for loose connections. That is a logical next step. However I agree what what JST is saying - but I would be looking for bad connections anyway and then go from there.

If all connections are good, I will have to review your data more thoroughly.

Thanks for the feedback. I'll get back with you asap.
RJ

auroracc said:

The probes were placed at the transformer terminals not the machine. We will look at the load side of the transformer. Does anyone know if the "stinger leg" comming from the phase converter (208V to ground) could be causing an issue?
Thanks,
RJ

Click to expand...

When using a Delta Wye transformer, the wild leg coming from the phase converter is weaker than the PoCo phases now affects all 3 phases.
Things get ugly when the control electronics in servos and spindle controllers go into a brownout condition (similar to a software crash or reboot) and the PWM now becomes DC on the windings. These conditions may only last a few seconds. Sooner or later you may have motor failures as random sections of windings get overheated until there is a burned open section.

Several years ago I was called by a new to me customer having motor burnout problems on their new $250K 5 axis machine. The OEM maintained that the power MUST be a Wye connection, although it ran properly with a Wye connection autotransformer. My advice was to run from a generator until you have real 3 Phase power. Generator was installed and no further problems since.

Bill

"Phase C has zero noticeable voltage drops." Does this phase coil have the primary powered by the PoCo phases?

Yes all connections need to be checked carefully, including any voltage taps in use.
An IR thermal thermometer is helpful in finding a hot connection under power.

All,
First I want to say thanks for all the feedback, Never having been on a forum before.
1)We went through and made sure all the lugs were tight, the ones on the secondary side were only hand tight (from the manufacture, I was not happy with that and never expected it). The machine is down and i have service coming in tommorow, I will see if this makes a difference.
2)I would love to have 3 phase power but at this point it's cost prohibitive ($ six figures) Although I agree that would be the best way to go. We also had a diesel generator 400V WYE and the machine sang like bird. Problem is the cost of the fuel even if I purchased one. We were using $1k a week with the install guys here. I know a lot of people would say well just get an industrial bld, but that's not an option at this point, so I'm stuck with trying to make the best of it.
3) Phase "C" is actually the high leg out of the phase converter.
4)I've also looked into some power conditioning equipment but from my understanding sometimes they don't play nice with inverters and drives. Anyone else had any luck with these devices?
Thanks,
RJ

The PP should be as good as powerco power, maybe better in voltage regulation. The idea that the "made" phase line is weaker is true of many RPCs, but not particularly true of a Phase Perfect, they should run a motor right up to the rating of the PP.. And, your experience with the other CNCs is that the PP runs them fine, even the ones with the step-down transformers, which ends to confirm.

Therefore, something in the particular setup on the new unit is the problem.

Now, you called the transformer a "step-up" unit, but really it is not, it is a 1:1 transformer, since 400V from a wye transformer is made by the delta to wye change. The voltage on each primary delta winding is 230V, and the voltage on each wye winding is also 230V, each phase is actually a 1:1 ratio.

To identify a problem output, it might be more productive to check phase to neutral, since that will point at ONE winding of the unit.

Loose connections: Yes they can be a problem. But usually, they make themselves known when there is any real current flow, because they will arc. Even if you do not SEE the arc, it will generally leave fairly obvious traces on the wire and the connector. Arcing also generated heat, so any sort of sustained arc will usually make obvious traces of overheating. Intermittent arcing will leave sooty deposits, and "weld marks". No loose connection in a power circuit can create a voltage drop of any significance without heating up. The record showing large drops should have, over that time, shown up with arc marks and other evidence.

That leaves some sort ov electronic issue. If the PP was being made unhappy by the load, that certainly could cause dropouts. I do not know the PP rating used on that machine, and the machine power requirements were not in the online info I dug up.

What is the size PP used?

What is the transformer rating?

What is the machine power requirement?

1)PP is a PT-380 96A rating with a 400A 4 sec inrush.
2)We tightened up all the connections the secondary side (from the manufacture) was not as tight as it should have been. All that being said it didn't make a difference, and we didn't find any arcing.
3)The max machine power requirement is 80A at 400V but in the power studies and everytime else we never saw it go over 40A at the primary side. If we were overdrawing on current I would expect that either the breaker would trip or the PP would shut itself down.
4)Had the machine tool tech out here today and he managed to fire the machine back up. He increased the DC V it was about 23.7V and increased it to 25.5V to no avail. The machine faulted out while it was sitting doing nothing. He's taking the service log back to Heidenhain to see if they can glean any info. The one thing that he didn't like seeing was the voltage variance on the secondary side of the transformer i.e. at the machine. It was fluctuating 5-8V while testing from phase to phase. Phase to ground was good. Still can't figure out why it's doing that.
5)Also waiting for more info from the POCO on the harmonics that they found.
6)I was surfing on line and found this company near me Applied Energy that has what they call a Phaseback. It's supposed to level out the voltage, clean up the low end harmonics, surge suppress etc. They actually came out yesterday and hooked up a unit for a trial. Unfortunatley it didn't make a difference.
7) Unfortunately no improvement so far. I don't know whether I mentioned it earlier or not but we made sure that we were well bonded with the grounding, that also hasn't helped
Thanks,
RJ

Home - Applied Energy

The third phase of a Phase Perfect is an inverter created PWM output. It is likely interacting and resonating with the machine drives' DC bus capacitors, causing the voltage swings, but also causing instability inside of the drives, which is being interpreted as "inverter and supply module readiness is missing" and "power module not ready".

I would agree with you "but" (and that's not to say it isn't happening) 1)we have placed "waveform correctors" downstream and upstream of the PP. (The AC/DC Solution | Environmental Potentials). From my understanding and the Electrical guy that has used them it not only has surge suppression but takes out those harmonics. The odd thing is that if it was the PP I would expect to have the machine fault out continously and it doesn't sometimes it may run for a day or so without any problem. My next step is to rent a 230V generator 3phase and 1phase to see if we can determine if it's the PP, Transformer or POCO.
Thanks,
RJ

I wouldn't put too much stock in that device, when companies sell this stuff and don't describe exactly what it is, it's usually snake oil... that web site is full of it.

It does begin to look as if the PP is "hunting", that it may be unable for some reason to settle on a stable voltage. But, that should be just as visible on the primary side as on the secondary side.

BUT... the information that the phase-to-ground voltage is good suggests a different possibility, which is that the PHASE ANGLE produced by the PP may be varying. That is one way to get a voltage change on JUST ONE pair of wires, with the other two pairs staying steady, and to have good phase to ground voltages. And that is the condition suggested by the monitor record.

Does that particular PP supply any other CNC equipment?

If not, then there is a chance the actual issue is in the PP itself. It could also be a resonance issue, in which case changing something, such as putting in a line reactor, should make a change in the problem... better or worse.