When a Texas/Louisiana-based customer was seeking an electrical contractor to help upgrade the drive systems on ten LeTourneau oilfield cranes, JC’s Marine Power & Distribution secured the order and suggested the use of drive technologies from Control Techniques.

The company proposed the use of a Unidrive SP AC variable speed drive for the boom, and two Control Techniques Mentor MP series DC regenerative drives for the swing and hoist.

“By changing to a Control Techniques variable speed drive for the boom we can ensure complete control over the speed and rate at which the boom moves, so that loads up to 50t are ‘feathered’ rather than ‘banged’ to the ground,” said John Costanza, president at JC’s Marine Oilfield Services.

The boom motor drive system comprises an SP5402 Unidrive variable speed AC drive rated at 210 Amps continuous, while the hook motor drive system features a Mentor MP420A4R DC drive rated at 420 Amps continuous. A Mentor MP210A4R, rated at 210 Amps continuous, is fitted to the swing motor drive system. All of the drives are purposely sized for twice the normal power required, which means the system never runs at its maximum capacity.

David Powers, LeTourneau crane operator on Atlantic 7 rig, likes the new control system, which carries a Certificate of Design Conformance from the American Bureau of Shipping (ABS). He said:“The new system gives the crane a better parameter of operation and is more responsive. Most importantly, these changes have made a much safer work environment.”

“Braking is automated, which promotes safety and takes responsibility away from the operator,” added Costanza. “Also, there is better reliability as the load is not being ‘snatched’.”

Further benefits delivered to the end user as a result of AC and DC drive technologies from Control Techniques include conformal coating on the PCBs, which helps impart protection in marine environments, while the large working temperature range is also advantageous.

Three cranes have already been completed with no reported down-time in the first 18 months of operation. The project to complete the upgrade of the 10 LeTourneau cranes will continue through to the end of 2017.