Seven of the most common causes of Transformer Failure, and how to reduce the likelihood of failure

Distribution Transformers are a critical element of any electricity supply system offering high levels of reliability with relatively low maintenance requirements. However, their reliability should not be taken for granted. Although it is very rare that transformer failure will happen, those that do often have a catastrophic impact.

When a transformer fails the cost of damages can far exceed the simple replacement cost. The aftermath of the failure must be cleaned up, damaged equipment must be repaired or replaced, and there are other losses that may be substantial including lost production time, damaged credibility, regulatory fines, or civil lawsuits.

Here are seven of the most common causes of transformer failure:             

  1. Age – The age of the transformer can lead to its failure. However, it’s not necessarily the calendar time, but the cumulative operating hours at a high load. A transformer with a continuous 24/7 cycle of high load will age about four times as fast as one with a 5-day 8-hour load cycle.
  2. Major Leakages – Moisture and oxygen can enter a transformer through leaking gaskets causing accelerated ageing of insulation and insulation failure. Leaks can be caused by cracks, tank damage, sealant damage, deformation, weld cracking and many other issues and have the potential to cause environmental harm if not adequately contained. Transformer failure investigation - transformer leaking from radiators
  3. Inadequate Maintenance – Transformer maintenance is primarily concerned with ensuring the level and condition of the oil and ensuring moisture does not enter the tank. Annual maintenance is the easiest way to be proactive in reducing the likelihood of transformer failures.
  4. Overloading / Overheating – Maintenance allows you to make sure the electrical load settings are appropriate for the specific type of transformer being used. Overloading causes overheating, and eventually, thermal degradation which will reduce the effectiveness of the winding insulation.
  5. Moisture – Moisture in a liquid-filled transformer can cause issues that result in irreversible damage to the insulation. If the transformer tank is not properly sealed, moisture will eventually work its way into the insulating fluid. In the case of free-breathing transformers, it is also possible for moisture to enter a transformer during the natural breathing process if the silica gel is not well maintained. transformer failure due to extra moisture
  6. Left to Disrepair – Transformers that are left to disrepair are often a tell-tale sign that transformer failure could happen. Substations that are overgrown with shrubbery, have the potential to result in damage by trees, obstruction of radiators and other external factors like animals, which could all influence the failure of the transformer. Transformer failure due to being left to disrepair
  7. Lightning Surges – Lightning surges are very capable of destroying the function of a transformer however due to a combination of transformer design and the low lightning density within the UK, this is less common a phenomenon compared to the above factors.

How to reduce Transformer Failure:

It is key to ensure transformers are designed and manufactured for their intended application. A good construction transformer fit for purpose should not fail prematurely provided an adequate maintenance regime is adopted. Transformers have a long-life expectancy unless something outside the design specification happens. It is vital to perform regular checks on the loading of your transformers. Electrical transformers that operate below the maximum load capacity have a longer lifespan.

Planned maintenance, inspection and testing will significantly reduce the number of transformer failures. Transformer preventive maintenance is very important, immediate preventative action can be taken to avoid any unexpected outages.

Bowers Electricals has a dedicated High Voltage Maintenance team that can offer full on-site maintenance of all your electrical plant and power equipment and provide ongoing support 24 hours a day, 365 days a year.

If your transformer does fail…

However, if your transformer fails, Bowers Electricals can assist with replacing and installing a new transformer. We hold in stock standard sizes on short lead times. Contact our sales team here; they will be happy to assist you in getting back up and running.

Posted on: 25.04.2023
Posted in: Transformers
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