ABB VFD delta high leg

wncjefftino said:
I swapped A and C on the VFD input, and the no current "followed" to the new location. I'm going to use the original VFD at a different location (still 240 delta system) to see if it's an ABB VFD issue.
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Don't swap, rotate. Move A to B, B to C, C to A. Repeat to get the lowest average current.

Across the line motor loads ahead of the VFD.

I doubt it will help at a VFD. Different type of load.
 
Jraef said:
Like most VFDs, the ABB drive is not looking at the voltage, it actually doesn't care. It's only looking a the DC bus RIPPLE to determine if there is a phase loss or not, and that is ALSO dependent on the load current.
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Good to know, but I doubt I will remember this.🙄
 
wncjefftino said:
There is 2 transformers on the pole.
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One thing that causes me headachs is utility supplied two transformer or open delta service not used as intended. I had one that had a quite large single phase 240 load added to the 'open' phase set.
Too much single phase load on the open set can drop the overall kVA rating of the bank below the calculated load and possibly lead to other serious problems.
The solution in that case was get the utility to add a 3rd transformer closing the delta that vastly increased stability and capacity without any other work needed.
 
I was back this morning and rotated the phases on the input to the VFD. The result was the same input phase loss fault. I rotated again and still the same result. I measured current and the no current "moves" as well.

I took phase to phase voltage readings:
AB 238
BC 222
AC 238

Phase to GND
118
199
118

That delta leg is lower than the readings I took a week or two ago.
 
wncjefftino said:
I was back this morning and rotated the phases on the input to the VFD. The result was the same input phase loss fault. I rotated again and still the same result. I measured current and the no current "moves" as well.

I took phase to phase voltage readings:
AB 238
BC 222
AC 238

Phase to GND
118
199
118

That delta leg is lower than the readings I took a week or two ago.
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AC should be the sum of AG + CG.
BG should be AG X 1.732

The fact that BC is significantly lower than AC or AB says the utility service transformers are under sized based on your loading profile.
 
Hv&Lv said:
Aren't VFDs wye?
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They may have a surge protector connected from each line to ground. They will be set up for 120 or 277 nominal to ground. Delta systems will have one or more lines that are higher voltage and will take out the surge protection. Many have a link, screw, etc. that you can remove if using on a delta system. you lose surge protection or at least a portion of it when you do so. Otherwise the front end of the drive is a three phase rectifier. I'm a little puzzled by OP's lost phase fault as most drives won't know this happened. If anything the DC bus voltage may run low if you lost an incoming line if the drive is supplying significant amount of output load. If output is at low enough level you may never know you lost an incoming line.
 
tortuga said:
One thing that causes me headachs is utility supplied two transformer or open delta service not used as intended. I had one that had a quite large single phase 240 load added to the 'open' phase set.
Too much single phase load on the open set can drop the overall kVA rating of the bank below the calculated load and possibly lead to other serious problems.
The solution in that case was get the utility to add a 3rd transformer closing the delta that vastly increased stability and capacity without any other work needed.
Click to expand...
If the "stinger pot" is significantly smaller than the other one, they never intended it to carry anything but a limited amount of third phase for three phase loads and that large single phase load should have been connected across the other transformer. If that transformer wasn't enough to handle the load then they should have had the supply upgraded when they added that load.
 
wncjefftino said:
I was back this morning and rotated the phases on the input to the VFD. The result was the same input phase loss fault. I rotated again and still the same result. I measured current and the no current "moves" as well.

I took phase to phase voltage readings:
AB 238
BC 222
AC 238

Phase to GND
118
199
118

That delta leg is lower than the readings I took a week or two ago.
Click to expand...
jim dungar said:
AC should be the sum of AG + CG.
BG should be AG X 1.732

The fact that BC is significantly lower than AC or AB says the utility service transformers are under sized based on your loading profile.
Click to expand...
I agree with Jim, sounds like possibly too small of source for the load it is trying to deliver, particularly the high leg unit may be too small. 238/118 isn't bad on the other unit, but ideally the voltage to high leg should be closer to 238 from each of the other lines and maybe 204-206 to ground.
 
kwired said:
238 from each of the other lines and maybe 204-206 to ground.
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The NEC, and our industry use nominal voltages. 240/120V High legs are always nominally 208V.
If you want to use measured voltages, instead of nominal, the high leg is always the A-B voltage x .867 or the A-N voltage x 1.732. This is all based on trigonometry.
(We often round measured voltages to the nearest full decimal which is why we have voltage systems of 208Y/120 and 480Y/277)
 
jim dungar said:
The NEC, and our industry use nominal voltages. 240/120V High legs are always nominally 208V.
If you want to use measured voltages, instead of nominal, the high leg is always the A-B voltage x .867 or the A-N voltage x 1.732. This is all based on trigonometry.
(We often round measured voltages to the nearest full decimal which is why we have voltage systems of 208Y/120 and 480Y/277)
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I understand all of that. I was just saying the 238/118 is within acceptable range, but the 222 and 199 are not, and are associated with that high leg, kind of indicates too much load on it and it can't deliver it, if it were not overloaded it too should read about 238 and maybe about 204 or so to ground.

This likely would go fairly unnoticed if it were not for the VFD involved. Apparently the drive is putting out most of it's rating as well or else it may not be seeing enough of a reduction or ripple in DC bus voltage to create the fault OP is getting.
 
I emailed our contact at our POCO to see if they would check the transformers since both the refrigeration guy and I have measured lower than normal voltage to ground on the high leg, 195V at a glycol chiller and 199V at my VFD.
 
wncjefftino said:
I emailed our contact at our POCO to see if they would check the transformers since both the refrigeration guy and I have measured lower than normal voltage to ground on the high leg, 195V at a glycol chiller and 199V at my VFD.
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Voltage to ground on the high leg doesn't mean anything to the motor. It only cares about Line to Line. Use those voltages.

The VFD may care, but not the motor.
 
ptonsparky said:
Voltage to ground on the high leg doesn't mean anything to the motor. It only cares about Line to Line. Use those voltages.
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If the measured high L-N does not correspond with the expected value, based on the measured low L-N, then your L-L voltages are no longer 60° apart resulting in unbalanced voltages to the motor.

When troubleshooting all voltages are important:
L-L
L-N
N-G.
 
240 VAC three phase Delta sucks. Yaskawa dealer here. Check to see if you can program the ABB drive to delta config. Not sure what else is going on here.
 
jim dungar said:
If the measured high L-N does not correspond with the expected value, based on the measured low L-N, then your L-L voltages are no longer 60° apart resulting in unbalanced voltages to the motor.

When troubleshooting all voltages are important:
L-L
L-N
N-G.
Click to expand...
I knew I'd get in trouble for that specific of a statement.

So how do they get other than 60 degree apart? And what would the resulting L-L voltages be at the 195 and 199?
 
I did my own math which could be totally wrong.
The 195 or 199 could be an indicator of uniform system VD under load, an indicator of a compromised connection(s), transformer overload. L-L checks would be needed to sort it out. Along with currents.

VFDs on Hi leg systems is different. issue.
 
ptonsparky said:
I knew I'd get in trouble for that specific of a statement.

So how do they get other than 60 degree apart? And what would the resulting L-L voltages be at the 195 and 199?
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If you plot it out to scale according to measured volts the resulting triangle is no longer going to be equal angles at every corner.

Was earlier said it was 238,238,222 for L-L voltage and 118,118,199 to N.

The transformer design is still 60 degrees all three corners, but drop in voltage because of too much loading on one side has distorted the effective output by changing the length of each side. The fact it is open delta probably makes it easier to change it. A full delta with three equal sized coils and balanced load may still have reduced voltage with load on it, but all sides should change by same ratio still leaving you with all same angles.
 
ptonsparky said:
I did my own math which could be totally wrong.
The 195 or 199 could be an indicator of uniform system VD under load, an indicator of a compromised connection(s), transformer overload. L-L checks would be needed to sort it out. Along with currents.

VFDs on Hi leg systems is different. issue.
Click to expand...
Some of us are suspecting transformer overload - particularly more of an issue with the high leg unit as the reasoning it is not a voltage drop of same magnitude as on the main unit. OP does not have uniform VD going on, presuming the voltages are where they should be if there is no load. I suppose POCO could possibly have a regulation issue and happens to be on the line supplying the high leg pot since the voltage on the other pot seems to be about where it would be expected to be. Other users would be having imbalance issues as well if they have three phase service and it may been caught sooner and resolved than if just one user is having imbalance voltage issues.
 
If my memory serves me right there are 2 transformers on the pole. There is 1 may be 2 other business besides us tapped to the larger of the two transformers and the other small one going to us.

I emailed our POCO rep., and he said that the voltages I gave him were within their voltage +/- 10%. Asked if we were seeing equipment issues. I replied with the forementioned VFD and speaking to the refrigeration guy the phase monitor is tripping our glycol system as well. Waiting on his reply.
 
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