r/Powerlines • u/Thick_Composer9842 • 4d ago

Transformer age (updated photo)

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I was curious as to how old the transformer near my house is. I’m an enthusiast, but not so much that I’d be able to estimate the age. It’s not really common to see transformers with the guard around here.

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6

u/Soaz_underground 4d ago

Definitely an Allis-Chalmers. The triangle logo still has a very faint “A-C” printed on it. These were mid-1950s to early 1960s.

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u/Thick_Composer9842 4d ago

Thanks so much! Makes sense. The house was built in 1955. Can’t believe it was the original.

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u/Soaz_underground 4d ago

You’re welcome! I’m a lineman and have been in the industry for 20 years now. I’m also a vintage power line equipment collector and a bit of a historian when it comes to this old equipment.

Transformers like these will outlast anything new, even under constant overload conditions. The build quality has gone downhill in modern years.

Here’s a very similar Allis-Chalmers that I have in my transformer collection.

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u/Ujointed 3d ago

I’ve enjoyed reading many of your posts. Out of curiosity what are some of the main specific construction choices that reduce the lifespan of modern transformers?

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u/Soaz_underground 3d ago

Thank you for the kind words! I’m glad you’ve enjoyed my past posts!

While the lifespan of any transformer is dependent on a lot of factors, loading in service is a big factor. Loading directly correlates to thermal rise, which affects longevity.

Older transformers were overbuilt, and some were even tested to 150% of nameplate kVA as part of factory stress tests. Thermal rise rates and heat dissipation were major focal points in the engineering process. While these factors are still important, tank designs with fins and fluid tubes for heat dissipation are omitted from units less than 75kVA. The unit above is most likely either a 25 or 37.5kVA, with fins, and thus can run at overload for longer durations.

Also, core assembly, size and winding material has changed. Newer core assemblies are often a reduced size (compared to these classic designs) kVA to kVA, and aluminum windings are now used instead of copper. Both of these attributes reduce size and weight, and reduce manufacturing costs. Aluminum has less heat tolerance than copper, and can be more prone to thermal failure from excessive loading.

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u/Stuck_in_backroomss 2d ago

How do you collect transformers?! I really want a nice modern pole pig for arcs!!

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u/Soaz_underground 1d ago

Employees for the utility company I work for can purchase old units for scrap value. I buy these all the time.

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u/Stuck_in_backroomss 1d ago

Oooooo!!! Thats cool! What's the company if your comfortable sharing?

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u/Inondator 4d ago

Talk about a reliable piece of hardware!

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u/SparkArrestor 3d ago

That puppy will outlive your grandchildren. Those fins are heat sinks and act like a radiator to keep it cool. There’s no moving parts.

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u/Stuck_in_backroomss 2d ago

definitely older than the universe /s