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Transformer Maintenance: The Importance Of Visual Inspections

Transformer Maintenance: The Importance Of Visual Inspections

Industrial organisations invest heavily in the electrical systems of their plants and spend just as much every in their upkeep. But in this article, we go over a tip that will not cost a cent and only requires some of your time: visual inspections. While it may not seem like it initially, the straightforward method of walking around a transformer or substation is vital to electric transformer testing and maintenance.

What to look for during transformer visual inspections


There are many things to look out for when doing a visual inspection, starting with leaks. The important thing to remember when searching for these leaks is that they will not always show oil leaking, as one may assume, especially if the leak occurs above the oil level. In such cases, the more pressing concern would be the introduction of atmosphere into the equipment. In this case, the atmosphere refers to oxygen, moisture, and other contaminants that can cause premature wear and ageing to the transformer. As such, look for these leaks and repair them as soon as possible.

The best way to determine if there are oil-free leaks on a transformer is by checking the pressure or vacuum gauge. The oil inside the equipment expands as it heats up and contracts as it cools, which means a sealed transformer will have pressure or a vacuum. However, seeing a “0” on the gauge does not necessarily mean there is a problem; you may have just caught the transformer going from pressure to a vacuum or vice versa. Therefore, check back once the load or ambient temperature has changed and allow the transformer to run cooler or hotter. If the gauge remains at “0”, the equipment likely has a leak above the oil level, as anything to the right of zero means pressure.

Paint condition

The next concern revolves around the transformer’s paint, which contributes to cooling the equipment. Try touching a transformer’s surface, and you will likely notice a chalky film on your hands once you pull away. This residue is normal from the constant exposure to the atmosphere. But once the paint starts to chip, flake, or peel, rust will inevitably form and cause the transformer to run hotter than normal.

When inspecting the transformer’s paint, be on the lookout for these four issues in particular:

  • Peeling – peeling results from moisture accumulating under the paint surface and causing flaking.
  • Cracking – paint inevitably hardens and becomes brittle over time, leaving cracks along the surface. Temperature changes in the metal, which causes it to expand and contract, can also lead to this issue.
  • Caulking – caulking is the white, chalky film mentioned earlier that develops on the paint due to sun exposure.
  • Rust – deteriorating metal forms rust that eventually causes leaks and pinholes.

When conducting the inspection, check between the radiators (especially along each radiator tube where the metal is thinnest), the gasketed area, and the inspection plates. In addition, you may want to look at the gauges and welded areas since these places must be inspected closely for leaks and paint chipping.


Just like rewinds or motor repair in Singapore, doing a thorough visual inspection of transformer units is a cost-effective measure that contributes significantly to the optimal performance and longevity of a transformer. It is also important to diagnose common transformer faults whenever you can. By dedicating a bit of time to look over the equipment, operators can quickly detect and address potential issues before they develop into bigger, costlier problems.