B 28 - Transformers in 1924-A century ago-Part 1

General Electric Review was the house journal of GE, USA. It published the latest developments and research reports by GE engineers on the electrical products manufactured by them. A century ago, every January, it published an annual product review surveying the developments and improvements in specific GE electrical products of the previous year.

Let us look at the 1924 January issue (Vol 27 No.1) of GE Review to understand the developments in transformers during the previous year's publication. John Liston of the GE Publicity Department covered the progress in electrical products in a paper titled “Some Developments in the Electric Industry during 1923.” On pages 31-36 of the journal, the progress in transformers is covered for 1923. Since GE was the leading transformer manufacturer in the world then, these reviews give us an insight into transformers a century ago.

Some key delivered transformers were

1)??? GE made 20 MVA 220 KV Generator Transformers, commissioned at Southern California Edison Company’s Power Station to transmit power at 220 kV to Eagle Pocket substation near Los Angeles.

2)??? 15 MVA 132/72 kV, three-phase,60 c/s Auto-Transformers

3)??? The 62.5 MVA 27.6/13.8 kV Auto-Transformer Bank was the largest transformer bank ever manufactured in the US. Since the single-phase transformers were installed in a closed cell with doors, the radiators were mounted as a separate bank outside the cell, a breakthrough for transformers.

These transformers were also distinctive in connecting the windings to the underground cables. Contrary to the usual practice of using standard outdoor oil-air porcelain bushings, they were designed to bring underground cables directly inside transformers, with their lead and connections so made that no live parts were exposed. There were no switches between the transformers and the power cables; all the switching was done at the generator end of the cable. HV oil-filled cable boxes were used widely in later years, mounted in transformers used in underground power stations and factories.

4)??? Water-cooled single-phase transformers of 22 MVA 39.5/68.5 /2.3 KV 25 c/s were made for Niagara Falls Power Company. Please see the photo of the active part.

5)??? Another record product was 17.1 MVA 2.95/11.8 KV 25 c/s 3 phase air blast cooled transformers for New York Edison Company.

6)??? The ratio adjuster ( tap-changer) was used for higher potentials and heavier currents. The maximum for 1922 was 110,000 volts, 500 amperes, and for 1923, 150,000 volts, 1200 amperes.

7)??? GE-made transformers with a 110 kV oil-filled cable box for terminating underground cable directly to the transformer. HV bushings and cable pot heads were bulk oil type, with an outer porcelain shell.

8) ” What is probably the largest order ever received for lighting service transformers included 5000 ( nos) 15 kv-a ?and 55 (nos) 2000 kv-a, 50-cycle units for use in the rebuilt city of Tokio, Japan .”

?9)??? A 15 MVA 118.8 kV transformer, transported with oil, exceeded the permissible movement limits over the rails. A two-section tank was used, with the lower end of the top section being slightly above the core level and coils. Thus, the top section could be removed, and the lower tank could be covered by a transportation cover, limiting the transportation height. On arrival at the destination, the top section, containing the water-cooling coil unit, was joined to the lower section without removing the oil from the latter. The use of such transportation cover during transport to the site was usual in later years. When making large transformers in India, I provided similar temporary covers during the 1960s and 70s to address stringent transport limitations with rail wagons.

The January 1925 issue (Vol 28 No1) covers progress in GE transformers during 1924. In the early part of the year, GE shipped two numbers, three-phase 60 c/s self-cooled transformers with a tertiary winding. These units had an efficiency of more than 99% with a voltage regulation of about 1.1 %. These were the most oversized self-cooled transformers ever made by GE. The largest water-cooled units were 20 MVA? 25 c/s three phase 22.25/11.5 kV transformers with an improved model of OLTC. 18.5 MVA 25 c/s three phases 11.8/2.95 kV transformer was the highest rated air blast cooled unit with reactor type OLTC. The progress of transformer rating during the first quarter of the twentieth century is given in the following figures:

?In Europe, Brown Boveri was the leading heavy electrical manufacturer. The papers published in their house journal during 1923 indicate the progress in transformers.

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