Although Nikola Tesla began his inventing work at the beginning of the 1880s, in the period from 1881 to 1882 while he was working for the Central Telegraph Office in Budapest, there is no information of him attempting to obtain a patent for any of his inventions. He applied for his first patent, for an electric arc lamp, after his arrival in the USA on March 30, 1884, immediately after leaving Edison’s company and founding his own Tesla Electric Light and Manufacturing. Over the next 43 years, up to 1928, Nikola Tesla protected many of his inventions with patents. The first was US patent no. 334,823 for a commutator for dynamo electric machines and the last US patent no. 1,655,114 for an apparatus for aerial transport. Tesla held a total of 112 registered US patents, while the total of Tesla’s patents in other countries has not yet been definitively determined. To date, 196 patents held by Tesla have been identified from another 26 countries, apart from the US. The largest number of these patents (30) were granted in France. Patents were also held in the United Kingdom (29), Belgium (27), Germany (21), Italy (19) and Austria (15) with other countries granting between one and seven patents. Thus Tesla held a total of at least 308 patents from 27 different countries on five continents. However, many of these patents related to the same inventions. The reason for the same invention being protected by several patents in various countries is the limited territory of patents, which means that they are valid only in the state in which they are granted. The collection of patents which protect the same invention in various countries is known as the patent family and these patents are known as equivalent patents. The first patent registered is known as the basic patent.
Analysis and comparison of Tesla’s patents has established that he was granted 116 basic patents for his inventions, 119 in the US and 7 in the UK, protecting a total of 125 inventions. The remaining 192 patents are equivalents of these basic patents. The inventions that Tesla protected in the largest number of countries were his pump and turbine (US patents 1,061,142 and 1,061,206), for which he was granted 23 patents in 22 countries. In contrast to this, 54 patents granted to Tesla in the US do not have equivalents in other countries. The greatest number of patent applications submitted by Tesla was in 1889, a total of 37 applications relating to his polyphase system.
The Archives of the Nikola Tesla Museum hold records of around 33 failed American patent applications, as well as patent applications which Tesla prepared but did not submit. Tesla also created a significant number of inventions for which he did not attempt to secure patent protection, such as the application of high frequency current for medical purposes.