RIG FLOOR EQUIPMENT

AC VFD power system enables efficient rig power distribution

Over the last 15 years, Variable Frequency Drives (VFD) have helped operators optimize power distribution for drilling and production equipment. The majority of offshore newbuilds are being constructed using the efficient AC VFDs because they have been proven to increase drilling effectiveness and rig safety, while reducing maintenance and expenditures. One global supplier of custom-engineered power delivery solutions to the traditional and alternative energy industries, American Electric Technologies, Inc. (AETI), is helping operators upgrade mature or traditional offshore rig systems with AC VFD power systems. For the past three decades, drilling equipment has been DC driven by Silicone Controlled Rectifier (SCR) systems, which converts AC to DC and enables motors to run at variable speeds. However, SCR voltage from DC systems has limited output. DC systems do not allow operators to optimize the equipment’s motor speed, which is directly proportional to SCR voltage output.

Some of the benefits AC VFDs provide to a typical draw works assembly include:

• More efficient drilling because of higher block speed, improved control and faster drilling functions
• Reduced weight of draw works assemblies
• Lowered capital and maintenance expenses due to the elimination of mechanical or eddy current electric brakes
• Simplified draw works drive train because the gearbox, drum and clutches are eliminated
• Reduced motor-cooling accessory requirements, which reduce drilling equipment weight
• Allows interface of individual pieces of equipment within the system and also enables digital communication between PC’s and PLC-controlled equipment
• Enhanced safety on the rig floor due to additional advanced automation features and arc-safe architecture
• Reduced overall maintenance because AC motors have no brushes to wear out.

American Electric’s AC VFD power system has advanced automation features and an arc-safe architecture.

These are just a few of the improvements experienced on one component of a rig’s operations. Operators of mature rigs can experience even greater efficiencies with a little planning at the onset of operations and factor in the effects of their power delivery system on equipment.