Yes thats an interesting point, I had assumed they were out 120 degrees based on those voltages. Maybe worth having one of the electricky people break out an oscilloscope to see if something is badly fucked lol
1 Like
I found them all with C5.06 set to 90%, so I’m guessing whoever installed them got this far already…and limited their capabilities based on that…but I also see that over all lab power consumption has gone up since they were installed and it looks VERY MUCH like the under-voltage has gotten worse recently.
This might be something to take up with the utility company. A failing transformer or loose connections somewhere can destroy equipment in the blink of an eye.
3 Likes
The diagram you posted is a 3 phase delta secondary configuration and is not common.
With a 120 208 3 phase you would be set up like this
You can likely make this piece of equipment a lot happier with a $200 boost transformer in the control cabinet.
Based on the 7.5 kw sharpied on the nameplate I’m guessing that is the motor size so you could get away with 1.5 kw boost at 10% to take you to 222.
1 Like
Only need 1.5kW boost transformer?!?
Or 7.5kW?
I’ve got 7 of the things (and another five still in crates).
Seems like a 50kW transformer might be more appropriate (or even 100kW).
Power company is boosting me 5% at the street tomorrow. We’ll see how that goes…
1 Like
5% might get you what you need!
I don’t know why but a 7.5 kw motor is = to 10 HP. The transformer has to be sized by the table in the NEC for 10 hp 3 phase at 220v
27 amps at 220 v 3 phase = 27A * 381V =10.287 KW.
The boost is sized to the percent of voltage boosted. So a 10.25 kw load boosted 10 percent voltage would only need a 1.025 kw. You might be able to get away with a 1 kw but it is right on the edge and I like to round up.
I’ve installed these on a bunch of equipment from overseas and never had any issue. Sometime I just wire them into the cord set on mobile equipment.
3 Likes
got it. thank you!
I used http://www.buckboostcalculator.com/index.cfm
feed it 200V 10% boost and 27A draw.
and it suggested 750SV43F, 750SV82F or 1.5S82F
looks like I can have a used one for less than $200…
https://www.ebay.com/itm/184129191673
You can have a new one for less than 200
Not square d
2 Likes
?
(please and thank you…)
1 Like
Careful, 27 amps is the motor load at 3 phase. Because it is fed with a phase converter drive you want to put into the calculator the 1 phase amperage
10.287 kw/ 202 volts= 50.92 amps
2 Likes
thank you (again)!
that is why I asked for confirmation (with links and shit…)
2 Likes
I like ACME for these.
Acme T111684 - Wire diagram H
I’m not sure if there would be any other subtantial loads coming off the control cabnet but based on the circuit wire size you should be okay.
ACME-MAIN_BUCK-BOOST-TRANSFORMERS.pdf (19.2 MB)
3 Likes
Wiggly Electrickery, electrons to and fro.
Wiggly Electrickery, what more you need to know?
Wiggly Electrickery, wiggled fast or slow
Wiggled with a VFD, ‘fuge spins on high or low.
Wiggled electrickery, your voltage is to low?
Wiggle in a transformer, to make that voltage so!
Wiggled Electrickery, wiggled rather fast.
Wiggled and then on & off, for DC it will pass.
Wiggly Electrickery, electrons to and fro.
How does that get the work done mate?
I’m not sure that that I know…
13 Likes
Did find that one controller had an 11kw drive in it while the other 6 were 7.5kw
Which explained a whole series of issues that had been plaguing that particular fuge.
I reprogrammed it to not actually provide 11kw to the 7.5kw motor, and nobody has told me it was broken since.
Not certain the extra few volts helped or not, but nobody has reported controller errors in months…
9 Likes
U is the symbol we use for voltage in Europe.
I guess this was chosen either to no confuse it with the corresponding unit V, or because V was already used for another parameter (big V for volume, lil v for velocity). Or also because U is used as well for potential energy in mechanics and thermodynamics. 
1 Like
I’ve got potential, but it’s confidential, no voltage for U
Reference (killers: somebody told me)
2 Likes
Turns out I had to set C5.06 to 60% to achieve joy (“don’t complain about the voltage till 132V”).
Documenting that change because I sent a tech here to figure out what I had done last time, and it didn’t work…
Chances are I had no biomass in there when I wrote it up.
2 Likes
I have been following this saga, and I’m very happy to hear! Haven’t been following much, but I do my best to read what you say… Didn’t care about much else
Can’t blame foolish folks for acting foolish…
And I’m only talking about people doubting you. One of these days I promise we’ll have the pleasure of meeting. Well it’ll be mine, and I doubt yours but whatever… You’re at the top of my list when I head that way, and don’t worry @Akoyeh will know when I’m coming!
And I guess I could have dm’ed this… But I guess I’ll be public about whom impresses me, and whom I hope to spend some time with! You Sir are high in my list, and the rest who were important know because we’re now family. But anyway… Back to regular scheduled broadcasting
4 Likes