Power systems protection in an oil field distribution system

Power systems protection for oil field distribution systems consists of protection for electrical submersible pump installations and their upstream electrical circuits. In this paper, a comprehensive protective device coordination and arc-flash hazard analysis is conducted for a large oil field distribution system. Various protection schemes are investigated and compared. This paper focuses on three areas: ESP installations protection using switchboards; protective device coordination of upstream electrical circuits of ESP wells; how to obtain the optimized protective device settings for both protection and arc-flash safety concerns. ESP installations protection using fuses is first addressed. ESP wells that cannot be protected by fuses are particularly investigated and a motor controller used with a fuse can provide a better protection for such ESP wells. A motor control center (MCC) for two large water injection pumps is used as a case study for the protective device coordination of upstream circuits of ESP wells. Nuisance tripping was experienced during a motor starting at the 1750HP water injection pump. The investigation indicates that improper relay settings at the MCC were the root cause. The optimized protective device settings can be achieved by conducting a protective device coordination study and an arc-flash hazard analysis by keeping both protection and arc safety in mind.