Patent ID: 7717193

Claim:
An electrically-powered well service rig comprising: a mobile platform for transporting the service rig; an engine-driven generator carried by the platform for generating AC power; a propulsion system carried by the platform for transporting the mobile platform service rig having a collapsible mast thereon, the propulsion system having a permanent magnet propulsion motor for driving the platform, a propulsion variable frequency drive (VFD) connected between the generator and the propulsion motor and a propulsion programmable logic controller (PLC) outputting speed setpoints to the propulsion VFD; a drawworks system carried by the platform and having blocks adapted for raising and lowering a plurality of tubulars into and out of a wellbore, the tubulars having one or more flag locations thereon, the drawworks system having at least a drawworks drum having drawworks cable wound thereon and rotatably driven by a permanent magnet drawworks motor; a drawworks VFD connected between the generator and the drawworks motor and a drawworks PLC outputting speed setpoints to the drawworks VFD; drawworks sensors for establishing measures of the running position of the one or more flag locations and communicating said measures to the drawworks PLC; and one or more target locations representing physical positions on or off the service rig wherein the drawworks PLC reduces the maximum speed setpoint for the drawworks VFD as the flag locations of the tubing are within a window distance of the target location; and a sandline system carried by the platform and adapted for raising and lowering a sandline tool into and out of a wellborn, the sandline system having at least a sandline drum having sandline cable wound thereon and rotatably driven by a permanent magnet sandline motor; a sandline VFD connected between the generator and the sandline motor and a sandline PLC for outputting speed data points to the sandline VFD.