That exactly confirms what I have been saying. The transformer isn't big enough.
Can we leave it at that, please? Before the mods take a dim view.
Step Up Transformer Issue
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Can we leave it at that, please? Before the mods take a dim view.
Thanks for the replies
Thanks for the replies
First of all, thank everyone so much for the responses!! I can't say that enough. I do work for the company but I work in the motor remanuracturing shop. It transformer side. But our salesman and pl leader both work with my side too so I got asked because our transformer designer has no experience once it leaves the drafting table!
Ive ran drives and esp motors a bunch. This is a little different. The drive does have an output sinewave filter. The motor is a surface motor with a step up between. 480 drive 4160 motor. Im not sure how they are determining they are only getting 840. That's one thing that I don't have the info I need. I'm wondering from some comments if they are even metering motor voltage? Our transformer is an ESP designed transformer, it is adjustable from 1400-4800 volts. So they can turn up the secondary if they need to. I just have never seen a transformer hit a wall like that. But again, I have such poor info from the site I'm not convinced of anything. I think the transformer is borderline. I'm just not sure if the transformer can saturate without raising input voltage? Does the pwm from the drive possible cause saturation? I like things that spin, not things that buzz and go pop! I'm just trying to learn from this.
Thanks
Thanks for the replies
First of all, thank everyone so much for the responses!! I can't say that enough. I do work for the company but I work in the motor remanuracturing shop. It transformer side. But our salesman and pl leader both work with my side too so I got asked because our transformer designer has no experience once it leaves the drafting table!
Ive ran drives and esp motors a bunch. This is a little different. The drive does have an output sinewave filter. The motor is a surface motor with a step up between. 480 drive 4160 motor. Im not sure how they are determining they are only getting 840. That's one thing that I don't have the info I need. I'm wondering from some comments if they are even metering motor voltage? Our transformer is an ESP designed transformer, it is adjustable from 1400-4800 volts. So they can turn up the secondary if they need to. I just have never seen a transformer hit a wall like that. But again, I have such poor info from the site I'm not convinced of anything. I think the transformer is borderline. I'm just not sure if the transformer can saturate without raising input voltage? Does the pwm from the drive possible cause saturation? I like things that spin, not things that buzz and go pop! I'm just trying to learn from this.
Thanks
the filter ought to reduce any harmonics to negligible levels
what does the motor drive?
did it start smoothly?
what i limit does the drive impose, if any?
did the xfmr burn up? damaged? overheat?
still running at 840 kva?
maybe the drive is limiting? filter + xfmr losses/charging + motor
the filter may be 100 kva
xfmr 40+
motor 840
close to 1000 kva, the drive rating
although the xfmr is marginal it should not hit a 'wall' at 95% rating
something else at play
or perhaps there is no issue
need more info
thanks for the update
what does the motor drive?
did it start smoothly?
what i limit does the drive impose, if any?
did the xfmr burn up? damaged? overheat?
still running at 840 kva?
maybe the drive is limiting? filter + xfmr losses/charging + motor
the filter may be 100 kva
xfmr 40+
motor 840
close to 1000 kva, the drive rating
although the xfmr is marginal it should not hit a 'wall' at 95% rating
something else at play
or perhaps there is no issue
need more info
thanks for the update
Last edited:
https://library.e.abb.com/public/a3be693a9ac8bf7bc125744e00339abe/ACS800_Sine_Filters_revG.pdf
page 35 might be helpful
xfmr S rating must => motor S rating
page 35 might be helpful
xfmr S rating must => motor S rating
Perhaps ambient temperature high limiting transformer output.
The transformer can saturate if voltage rises above its input voltage rating. A transformer is usually designed to operate near its saturation region. So any over voltage from pwm drive could damage it. But no over voltage from pwm drive as the transformer is not damaged.
The sine filter is on the output of the drive.
Harmonics are usually a consideration on the input side.
If there is any asymmetry in the PWM output then it could cause saturation. That's why we used transformers with an air gap in the core design. I don't know if the output sine filter would reduce that possibility.
Which it doesn't appear to be.
This (from P39) is quite interesting and may be relevant to the issue:
If the transformer is receiving lower than rated input voltage, it will produce lower than rated output voltage.
It's a point Jraef brought up earlier.
In other words a DC component from PWM drive.
It's a possibility.
That possibility could last but for a short time till the DC component decays to zero and the wave shape becomes symmetrical. So I think if the motor is switched on some time after the drive, issue due to any transformer saturation may be overcome, provided such a switching scheme is feasible.
If it's lack of symmetry in the PWM waveform it won't be transient.
Any illustrations please because I think only faulty equipment generate permanent asymmetrical wave form and associated even harmonics.
If we could be absolutely certain that there was perfect symmetry we wouldn't go with gapped transformers. But we do.
One such was a pumping station in Yorkshire where we installed four 760kW VSDs that needed output step up transformers. So very similar rating to that of the OP which is why I picked thaat one.
This isn't an illustration. It is a real life example.
I still believe air gap was providedd to ride through short time asymmetry instead of going for bigger size iron core.:slaphead: If you are pleased to present the waveforms here, I am ready to change my mind.:thumbsup:
it is xfmr 875 > 845 motor
doubt it, likely first thing checked
plus multi-tap xfmr
again, I doubt voltage related
too easy
imo no issue, just misunderstanding and/or lack of info
motor is making 99% of rated load
xfmr at 95%
drive less than 90%
obviously
it is to smooth the output...make it more 'sine' like...by attenuating harmonics in relation to the fundemenal, generally switching f range
it is an LC filter, L is series C delta in parallel
notch = 1/((LC)^1/2)
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