Microprocessor-based overfluxing relay for a generator transformer

✍ Scribed by H.K. Verma; A.M. Basha

• Publisher: Elsevier Science
• Year: 1987
• Weight: 553 KB
• Volume: 10
• Category: Article
• ISSN: 0745-7138
• DOI: 10.1016/0745-7138(87)90016-9

✦ Synopsis

This paper describes a microprocessor-based overlluxing relay meant to protect a generator transformer under over-excitation conditions. The relay continuously monitors the system voltage and frequency and takes alarm and trip decisions on the basis of transformer iron losses computed by the microprocessor. An alarm signal is given when the total iron loss exceeds a predetermined threshold value continually for half a second and a trip signal is issued if the condition continues for 5-99 s (adjustable). The operating value of iron loss is adjustable over the range of 1.1 to 1.5 times the iron loss at rated voltage and rated frequency. A relay prototype based on an &bit microprocessor 8085A has been tested successfully in the laboratory.