All Articles

Should I repair or replace my transformer?

If your transformer is nearing the end of its life, you have a decision to make: to order a replacement or repair the transformer you have.

February 22, 2022

Maddox transformer tech working on a padmount transformer

If your transformer is nearing the end of its life, or if a recent test indicates that there’s a problem, you have a decision to make: to order a replacement unit or repair the one you have.

In the past, the simplest choice would’ve been to replace the old one. But given the supply chain crisis of 2022 and its effects on lead times, buying a new transformer might not be the best option. After all, you probably can’t wait on extended lead times to get a new unit, and although Maddox has thousands of new and reconditioned transformers in stock and ready-to-ship, your transformer may be unique enough that a replacement is not readily available on the market.

So that leaves one option: repairing your existing unit. In this article, you’ll discover a quick guide to determining whether your transformer can be repaired, how to get it repaired, how to streamline the process, and what the benefits of repairing are compared to those of replacing your unit.

1. Can my transformer be repaired

The first step in repairing your unit is determining if it’s technically possible or advisable to do so.

If your transformer has a catastrophic failure, replacing it is really the only option. Most catastrophic failures are caused by:

  • Overheating due to excessive loading
  • A fault in the system (like when insulation breaks down and the windings of the same coil short to each other)
  • Natural disasters like storms or lightning

If your unit hasn’t experienced any of these problems, it can most likely be repaired. Transformers that are good candidates for repair often have components that have just aged and need replacing. Leaking bushings, worn-out gauges, peeling paint, and signs of rust are all common problems that can easily be resolved, allowing your transformer to run well for many years.

There are a number of other problems that can occur inside the transformer. If you detect them early enough, most can be repaired. This is why it’s important to conduct regular tests to detect issues before they become serious.

For example, a common routine test is a dissolved gas analysis (DGA) of your transformer oil, which you can learn more about from our friends over at SD Myers. Let’s say you run a DGA and discover the presence of excess dissolved gasses in the transformer. It could be evidence of a loosened connection, resulting in overheating. Over time (especially in areas with high ambient vibration), some connections may slacken their hold, creating small gaps where arcs can occur. A common example may be problems in the tap changer due to the numerous connection points on the device itself. If you discover these and other problems early, the repair is relatively simple and affordable.

2. If I find a problem with my transformer, what should I do?

If a test like a DGA indicates a problem, the best approach is to:

  • (1) Run another test to confirm
  • (2) Review the results with an expert (like the engineers at Maddox) to determine if the transformer is worth repairing
  • (3) Get the transformer into the shop for a more thorough evaluation in a controlled environment.

At Maddox, we run a full battery of tests to diagnose possible problems and assess the overall quality and condition of the transformer core and coil assembly. Read a detailed description on testing and how Maddox uses certain tests to evaluate the condition of your transformer.

3. Why should I send the transformer to the shop? Can’t you just fix it in the field?

Like any specialized piece of equipment—such as a car—transformers can develop problems that are difficult to properly diagnose in the field. Sometimes, field tests struggle to indicate or report a problem accurately. The number of tests available to a field technician is also limited, making a field inspection less thorough than one performed in a controlled production space.

When your transformer comes to Maddox, everything is done in a controlled environment, from the initial evaluation to the final stage of the repair. This ensures the problem is correctly diagnosed and corrected. This also allows us to run the transformer through the repair process with the same rigorous standards applied to the manufacture of new or reconditioned units.

4. Is it quicker to repair or replace?

If your primary concern is lead time, repair is almost always quicker than buying a new unit—and this is especially true given the current supply chain crisis.

However, replacing the damaged unit with a reconditioned one can sometimes be just as fast or faster than repairing or replacing it with a brand-new unit. If an available reconditioned unit matches the dimensions of the unit in need of repair, you can sell the failing one and replace it with the reconditioned one. Maddox has thousands of reconditioned, ready-to-ship transformers in stock for most common voltage configurations. These are typically available with a warranty comparable or identical to the warranties of newly manufactured units.

5. How do I maintain power while my transformer is being repaired?

Ideally, you would have a spare transformer with identical specifications, but we know this isn’t always the case.

Power can be temporarily maintained by renting a transformer. Our team can help you plan how to maintain your power while your permanent transformer is being repaired.

6. Are there other benefits to repair vs buying a new transformer?

If you have a transformer with a unique dimensional profile, a repair can avoid painstaking retrofit issues. The cost to repair an existing unit will generally be lower than building a custom retrofit unit because it saves us from having to design a new tank to match the current unit. In addition, if we bring the transformer into the shop, we can use the existing enclosure and either fit a replacement core and coil from stock or rewind the old unit with a new coil assembly. This is a great option in a market that’s going to be supply constrained for the foreseeable future.

7. Why should I trust Maddox to repair my transformer?

We are equipped with state-of-the-art repair facilities. We also possess the experience and expertise to tackle the most challenging repair scenarios. When performed under these conditions, repairing your current unit can result in the same level of reliable performance as buying a reconditioned or brand new unit.


Today, repairing your transformer may be your most economical and efficient option for keeping the power on, particularly when:

  • You can't wait for new production lead times, and reconditioned units are not readily available
  • You have a challenging retrofit situation

There are many other situations where a repair job may make sense. But even if you decide to replace a failed or aging transformer, you may want to consider repairing the old one anyway and keeping it on hand as a spare. This will improve the redundancy and resiliency of your electrical infrastructure.

If you think a transformer repair might be the best option for you right now, please contact us today. Our team is ready to help you find the right solution.

Maddox padmount transformer loaded on truck

Get more info

Find out how Maddox can power on your next project
Thank you!
Your submission has been received!
Oops! Something went wrong while submitting the form.