These biographies of George Westinghouse have been written since his death in 1914.
A Biography of George Westinghouse (1921) by Henry G. Prout, an engineer, long-time employee, and close Westinghouse associate
George Westinghouse - Fabulous Inventor (1941) by H. Gordon Garbedian, Columbia University professor and science writer.
George Westinghouse 1846 - 1914 (1914), writer Arthur Warren put together this 32-page timeline of the recently deceased George Westinghouse.
Here are two biographies written for young adults.
Inventive Wizard - George Westinghouse (1962) written by I. E. Levine, author of a biographies of famous people for young adults
While not biographies, here are two other excellent Westinghouse reads.
Empires of Light: Edison, Tesla, Westinghouse and the Race to Electrify the World (2002) by Jill Jonnes
The Last Days of Night (2016) by Graham Moore, a novel and basis for the movie of the same name
Complete copies of the first three books are available though this archive. The others can be purchased online or through its publisher.