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Benefits and risks of buying reconditioned transformers

Is buying a reconditioned transformer safe? Should I just buy new? Reconditioned transformers are a great option and can be trusted to operate safely.

February 13, 2020

Maddox transformer tech welding transformer

This article primarily discusses medium voltage, oil-filled distribution transformers, but the same logic can be applied to most other types of transformers as well.

To begin, we should understand why buying a reconditioned transformer—unlike so many other types of reconditioned equipment—is a sound consideration. Not all equipment easily lends itself to being reconditioned, just by virtue of its design. However, this isn’t the case with most transformers.

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Why Transformer Reconditioning Is Practical

For a product to be economically practical for reconditioning, it must meet the following criteria:

  • Not subject to rapid technological obsolescence.
  • Not easily compromised by use.
  • The cost to rebuild must be significantly lower than the cost to build new.

Transformers meet all three requirements!

  • Although manufacturing improvements have been made, basic transformer technology of how transformer work has remained the same since its invention.
  • Since it relies on simple electromagnetic induction to function, transformers have no moving parts that wear out over time due to mechanical stresses. This is the secret to the average 30-year expected lifespan with very little maintenance.
  • Unless it needs to be completely rewound, transformers are relatively inexpensive to repair compared to the cost of building new.

Having established that there is indeed an economic case for remanufactured transformers, we will now analyze the benefits and risks.

The Benefits

1) Speed Of Delivery

New transformer manufacturing lead times in the US stand between 10 and 30 weeks, depending on market conditions. This time frame is simply not an option for many projects, especially in emergency replacement situations. Maddox's reconditioning lead times stand between 1 and 3 weeks. Additionally, the US has one of the oldest, and therefore most colloquial distribution systems, meaning that dozens of different distribution voltages exist. This lack of standardization means that almost every single transformer is still engineered-to-order to this day. This sets the cost of maintaining a sufficient inventory far outside the scope of most electrical distributors. As a result, this creates an opportunity for rebuilders to maintain an inventory with a broad range of voltages to fill needs as they arise.

2) Lower Cost

Remanufactured transformers tend to be between 10% and 40% lower in cost than new transformers. But what about savings in power costs with new, more efficient designs? While slight efficiency gains have been made in transformer design (around 1-2% as of DOE 2016), the savings in utility power bills will never offset the added upfront cost of a new transformer.

3) Lower Risk Of Failure

The vast majority of transformer failures happen immediately upon energization. Relatively few failures occur between year 3 and year 30 of service. This means that if a transformer has successfully been energized, has served for a time, and has been removed from service with no issues, the secondary buyer of such a unit has the added assurance of getting a transformer that has already proven itself in the field.

4) Lower Environmental Impact

Some propose that newer, more efficient transformers are more environmentally friendly due to lower losses. However, the slight efficiency gains made in recent years will never offset the environmental impact of manufacturing a new transformer. According to the EPA, manufacturing produces 5% of total U.S. greenhouse gas emissions. The rebuilding process produces almost no greenhouse gasses. So go green—buy reconditioned!

A Maddox shop worker reconditioning a liquid filled padmount transformer

The Risks

1) Issues Created By Low-quality Rebuilders

The transformer may have been taken out of service with no issues, but a low-quality rebuilder may have introduced an issue not previously present through poor workmanship.

2) Shortened Life-span Due To Unknown History

A previous owner may have gotten rid of the transformer because of some known issue.

Minimizing The Risks

A quality rebuilder can easily offset these considerable risks. This is why it’s key that you qualify not just the product but also the rebuilder. Before buying any reconditioned transformer, make sure that the company producing the transformer can, at a minimum:


Transformer reconditioning has been a niche industry since nearly the invention of transformer technology. Buying a reconditioned transformer is often an excellent option when you need to meet project deadlines and budgets. New is not necessarily better than reconditioned, but you should always do your due diligence and qualify the rebuilder to ensure you are getting a quality product.

Maddox Industrial Transformer specializes in new and reconditioned 3-phase transformers, keeping thousands in stock at all times. Contact us today to see how we can help you! Whatever your needs, Maddox has both new and reconditioned solutions for your project.

*More About DGA Results

The oil inside a transformer acts as an electrical insulator and a cooling medium. It also gives us an excellent diagnostic tool. Any internal issue with the transformer (such as arcing or overheating) changes the chemical makeup of the fluid and produces combustible gasses. These gasses are easily tested for through DGA testing. This testing gives you an idea of the unit’s history. If some gasses do show up, the rebuilder should be able to explain why they are present and how they intend to fix the issue that caused the gassing in the first place. Transformers that have been “run hard” by over-heating or over-loading often have some gas build-up caused by insulation paper breakdown. It is important to know the condition of the transformer PRIOR to having it rebuilt. Some low-quality rebuilders will simply replace the oil with new in an attempt to erase the evidence of abuse.
Remanufactured and reman transformers, refurb, or refurbished transformer

Maddox padmount transformer loaded on truck

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