What is the purpose of anchoring a transformer that weighs 15,000lbs?
What is the purpose of anchoring a transformer that weighs 15,000lbs?
(OP)
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?
Do utilities anchor transformers to their concrete pads?






RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Not always done in times of old, but it is generally a requirement today due to seismic concerns, as David pointed out.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
We had a reason we did what we did, as the concrete pad wasn't wide enough to do it as it was shown. So you guys are saying an earthquake force comes along, enough force on its own could move a 15,000 dead weight...and those anchor bolts are going to hold that down?
I'd like to know how they determine the size, strength and where those bolts gotta be placed in order really know that.
It all comes down to money, such a trivial thing will end up costing $1000s to fix. It always does.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
A.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
OK that bolts could help ride through a mild earthquake. But the tougher ones?
OP: What are the typical magnitudes of your earthquakes? Ours are 1. mostly absent and 2. infrequent and 3. below 2 on the Richter scale. We had one around 30 years ago. Then I thought it was the neighbour's wife that hit the barn door (outhouse, 50 m away) with the tractor again.
If you are in a similarly geologically quiet zone, you may get away with the installation as-is.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
http://www.iitk.ac.in/nicee/wcee/article/13_1605.p...
http://www.asce.org/uploadedFiles/Institutes/Techn...
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Again we did anchor these transformers firmly to the concrete, but we went through some other tabs on the base that we were told are there to attach the transformer to shipping pallets. we will end up changing it I'm sure and eat all the costs. 15000 lbs in a footprint of about 3' x 7' oh and about 21 huge underground primary and secondary feeders are attached to this thing...I'm still having a hard time believing this.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Definitely it is better to anchor the base of transformer to foundation esp in earthquake prone areas. It is not a good practice to leave alone as the tank base can slide even under slight tremors.
The standards for Seismic design of Transformers are covered in the following:
IEEE Standard 693-2005 Recommended Guide for design of substation
IEEE Standard C57.114-1990 Seismic Guide for Transformers &Reactors (withdrawn in 1996)
IEC TS 61463 -2000- Bushing seismic Qualifications
IEEE Standard 1527 –2006 Recommended Practice for the design of flexible bus work in seismically active areas.
The above standards do cover about anchoring:
Quote
4.2 Foundations. The transformer and all interconnected equipment should be placed on a monolithic foundation so as to reduce differential movement due to the design earthquake. Provision should be made to accommodate expected differential motions between equipment mounted on separate foundations but which are interconnected. Provision should also be made for interconnected equipment mounted on the same foundation but having differing frequency content. Lastly, consideration should be given to the interaction of underground conduits and the foundations. Foundations should withstand all forces resulting from the design earthquake in the vertical and horizontal directions simultaneously. A comprehensive soil survey is recommended to determine if any unusual conditions exist at the site that would warrant special design considerations for the foundations.
4.3 Anchoring. It is recommended that transformers be anchored by welding the base to structural steel members embedded in or firmly anchored to a concrete foundation. Size, location, and type of welds should be shown on the manufacturer’s drawings. All welds must conform to applicable AWS specifications. AISC weld allowables should be used. However, the one-third increase in weld allowable stress due to earthquake loads should not be permitted. If bolts are to be used, size, strength, location, and materials should be shown on the manufacturer’s drawings. The size and strength of the anchor bolts should be determined by bolt material allowable stresses. However, the one-third increase in bolt allowable stresses due to earthquake loads should not be permitted. It is recommended that mild ductile steel, such as A36 or A307, be used, and that design philosophy such as stated in the article, “Design of Threaded Anchor Bolts” by John G. Shipp and Edward R. Harringer, Engineering Journal, AISC, in the second quarter of 1983, be followed. The length of embedment and the type of bonding to that portion of the anchor system within the foundation should be determined by the user and should be greater than the strength of the bolts attaching the equipment to the foundation. Consideration should be given by the user to any unequal distribution of dynamic earthquake loadings on the anchor bolts. All anchor systems must withstand the forces resulting from the design earthquake. (from 1990 IEEE standard)
UNQUOTE
As you can see there are two practices –weld the base of transformer to the anchored plate on foundation (popular in US) or use M24 or M36 Foundation bolts on either (longer) sides of transformer. Bolts are taken from the roller frames mounted on rails on foundation.(one or two bolts from each frame). This is found popular in Japan (where they experience maximum number of minor tremors)and also followed in India.
Another point to remember is higher the load, less g it can tolerate!
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Reason enough?
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Is there anything in any standard that requires anchoring a transformer for the express purpose of keeping it intact during a fault? It's much more likely than a 8.0 earthquake yet I don't recall ever seeing anything like that.
As I pointed out, an earthquake would be an extreme rarity. I used to work for a chemical company that has and still does have on every drawing "Minimum Essential design is the requirement" and is the company policy. And another thing they had in their specs I always remember..."do not design for catastrophic failure". Doing either costs money. And money is not an unlimited resource. The money you spend unnecessarily could have been perhaps used for something much more beneficial. This won't be that big a deal but just thinking this way is what bothers me.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Don't do it.
In this case, the solution is simple, not actually very expensive in the big scheme of "providing power after an earthquake", and straightforward.
Look up the Code,
Understand the relevant parts of the Code,
and, finally, Follow the Code.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
A power company or a chemical company would probably be criminally negligent if they didn't design to seismic standards in San Francisco. I'm not arguing that.
This is a no risk seismic zone. But a generic detail is ruling the day and trumping a reasonable installation and changing it will just add cost to the project. The problem is this mentality doesn't just show itself once like here...it's all over the place. And America wonders why it can't compete.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
A quake in Charleston broke chimneys across the Atlantic seaboard.
We were woken up by an earthquake across the border in Alabama from a quake that was felt over in South Carolina.
A nuke power plant in Virginia was shutdown by a quake there.
There is an active fault down the St Lawrence River bed with regular earthquakes.
Where do you think is a non-seismic zone in the US?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Where these transformers are anchored in 4 places are within 6" of where the mfg says to anchor, through the same gauge steel at the 4 corners.
The pads were not designed or installed by us and the underground conduits were not installed perfectly. The pad left maybe 5" on each side in the long direction - not much. In order to get the transformer to fit over the duct banks it had to encroach on this 5" leaving even less room and no room to anchor as per the mfg detail. And that's how things are in construction.
So what would you do? I guess we could have them remove the xfmrs, bust out all the duct bank, send it back to engineering and have them redesign the pads and bust all them out too. we must get it exactly per a generic detail to plan for an earthquake that hasn't ever happened because those anchors will save the day.
Or perhaps we could stand back a say what do these anchors really do? And will it really make any difference if they were moved slightly? Call me crazy.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
1) Evaluate the manufacturer's design;
2) Evaluate your as-installed design; and
3) If the former is superior to the latter, engineer the difference?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
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.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
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.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
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.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
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.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
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.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Si duri puer ingeni videtur,
preconem facias vel architectum.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
Consider specifying impact recorders for shipment. They will tell you the acceleration forces experienced.
RE: What is the purpose of anchoring a transformer that weighs 15,000lbs?
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.