OVERLOAD PROTECTION SYSTEM FOR THREE-PHASE SUBMERSIBLE PUMP MOTOR

摘要

Overload protection of a three-phase submersible pump motor, such as the type used downhole in an oil well, is obtained with a solid state digital logic control system that monitors each of the three phase currents and shuts the pump motor down if any of those phase currents indicates an overload condition. A time delay is introduced before shutdown to avoid undesired nuisance shutdowns otherwise caused by transient or momentary conditions. The shutdown time delay is variable and is inversely proportional to the amount of overload in order that greater overloads result in faster shutdown.