Abstract: A surface rig system includes components that consume power (e.g., using electrical motors). The power consumption of the components is monitored and used to infer other operational parameters. Illustratively, power consumption (e.g., current draw) of a shale shaker is monitored and used to infer: the volume of cuttings on the screen; changes in fluid viscosity, density, or rheology; health of the shaker screen; fluid cycle times; or screen clogging/blinding. Power consumption of pumps, fluid agitators, draw works, and other devices can also be monitored and used to infer parameters such as: fluid viscosity, density or rheology; hook load, or fluid slugging. Based on inferred parameters, changes may be made or advised for operation of equipment, including a shale shaker, downhole tool, pump, shaker screen, top drive, drilling fluid, or draw works.