What is the purpose of anchoring a transformer that weighs 15,000lbs? 2

[bdn2004]

I look at the work we are performing and just wonder why do we have to anchor such a big heavy piece of equipment?
Do utilities anchor transformers to their concrete pads?

 

[racookpe1978]

Yeah - What Lionel said above: Have the company that put in the bad pad pay for a simple - BUT ADEQUATELY DESIGNED! - "adapter pad" between the anchors in the concrete pad and an "acceptable" location on the transformer body/frame/side tank walls.

The turnover resistance is what you require, not the "use of a hole on the side of the transformer" placed there for anchoring the transformer "as intended" ...

But, no, you do not have a ethical ability to decide "I am not going to anchor the transformer because it will be expensive ..." Unless you sign the insurance bill for your company.

 

[bdn2004]

The client is aware of the reason the anchors won't go in as detailed. It's obvious. When we first installed these transformers the doors wouldn't properly close on the high voltage air terminal chambers. And the reason was because the pads weren't perfectly level. But instead of shimming them up what did they say? We were at fault for not surveying the pads before we set them. So we took the transformers off the pads and those that did the pads came back out and leveled them.
See what I say of the mentality here.
It cost thousands for both companies. And gained what?
Arguing or suing a client who is paying you millions to do projects is impractical. You might win the battle but you will forever lose their business. So you do what they say. Blaming the other company won't work either. Been there done that.

 

[LionelHutz]

Well if you're not willing to force responsibility onto the party responsible for messing up the pad then you'll have to suck-it-up and just fix it yourself.

 

[bdn2004]

I can see those that poured the pads saying it was the engineering company's fault because the duct bank was sized too big and they didn't leave enough space to begin with. No room whatsoever was left to make any adjustments. The ducts would have had to be in there to the 1/10 of an inch for this to have worked out. I don't think people that pour these kinds of things are used to that kind of precision.
And then I can hear the engineers say it is the mfg fault for not making the termination chambers big enough. And then I can hear the mfg say it's worked for everyone else.

We haven't done this yet, actually thanks for your comments I will suggest it to tptb that we shouldn't have to take the hit for this.

 

[FPelec]

In the last years, our substations have been hit by significant earthquakes (e.g. in Aquila in 2006, PGA=0.675g and Emilia Romagna, PGA>0.3 g).
Some equipment suffered heavy damage and had to be replaced: 420 kV CBs were find to be the weakest point.
Our EHV/HV ATRs, which were not fixed to the ground, did not suffered heavy damages: only in one case 420 kV porcellain bushings, which were actually rated only up to 0.3 g, were damaged.
In fact active part of the transformer is designed to resist significantly higer mechanical stress durind transportation (often exceeding 0.5g) and during short circuits. Use of RIP bushing with silicon housing, will substantially reinforce the transformers, which however even without anchoring are probably the most robust equipment in a substation, if compared to CBs, CTs and VTs...


Si duri puer ingeni videtur,
preconem facias vel architectum.

 

[bdn2004]

FPelec,
I think you make an excellent point...that your transformers and all transformers are made to sustain minor vibrations just so they can be transported. The last transformers we bought were made in Europe. They travelled by truck, by ship, by rail and again by truck before they arrived on our site. Just think of all the jarring and vibration they went through traveling and during the multiple times they are lifted and sat back down. It would interesting to me to find out what the g scale equals on the Richter scale.
As a follow up on this...as I knew we would we are changing all these out. When you are fighting against a mfg detail you will lose every time. Even the NEC requires that you install per the mfg instructions...as it should be. Actually after a closer look we could have in most situations installed per that detail. We did have to deviate some as described but we did them all that way. Our major fault is that we didn't even look at the detail. Lesson learned for me even routine installations you've done a 100 times look at the mfg literature for installation. And any deviation you best get TPTB to buy in before you do it.

 

[ogbuehi]

The reasoning I would think that you anchor the transformers down is because of minor vibrations, such as those caused by big rig trucks, trains, or airplanes. I don't think that any one of those on its own would cause the transformer to vibrate off the pad, but over time you could find yourself looking at an outage caused by that has "magically" fallen off of its pad (assuming that it wasn't hit by a vehicle). I've observed a few un-anchored transformers that were very cock-eyed on the pad in a very low seismic area. The sum of a bunch of very small vibrations could cause the transformers to move off its pad.

 

[FPelec]

bdn2004, there is no precise equivalence between Richter scale and peak ground acceleration (g); however some rules of thumb apply. For instance the Italian standard CEI 75-16 "Environmental conditions appearing in nature - Earthquake vibration and shock" (there should be an equivalent IEC standard) reports some correspondances: 0.5 g are associated to Richter scales >7. See the attached files for further information.


Si duri puer ingeni videtur,
preconem facias vel architectum.

 

[stevenal]

bdn2004,

Consider specifying impact recorders for shipment. They will tell you the acceleration forces experienced.

 

[oldrunner]

Read ASCE Manual 96 for a better understanding of substations (and transformers) for performance during seismic events. At a minimum, use .10g.
Travel forces of transformers from the manufacturer's plant to the final destination can be many times greater than the seismic requirements, but that only addresses the core/coils as the transformer is not dressed at that point.