Method for automatic cable tension on a reel

Abstract

The method of controlling the tension to an umbilical wrapped on the spool of an offshore reel when the umbilical is being normally deployed or retrieved, comprising providing a motor, sensing the number of wraps of cable on the reel, automatically calculating the radius to the current wrap being deployed, and automatically controlling the motor torque to produce the desired tension.

1 . The method of controlling the tension on an umbilical wrapped on the spool of an offshore reel, comprising
 providing a motor,   providing controls which determine the approximate radius between the centerline of the spool and the centerline of the umbilical on the spool as it leaves the spool,   automatically controlling the torque output of said motor generally in proportion to the said approximate radius.   
     
     
         2 . The method of  claim 1 , further comprising determining said approximate radius by counting the rotations of the spool. 
     
     
         3 . The method of  claim 1 , further comprising locking said spool with an instrumented load pin, releasing said brakes calibrating said tension as a function of said motor. 
     
     
         4 . The method of  claim 1 , further comprising adjusting the torque output of said motor by controlling the magnitude of the supply pressure to said motor. 
     
     
         5 . The method of  claim 4 , further comprising locking said spool with an instrumented load pin, releasing said brakes calibrating said tension as a function of said supply pressure to said motor. 
     
     
         6 . The method of  claim 1 , further comprising
 providing an automatic controller,   inputting desired tension, spool drum diameter, spool flange outer diameter, spool width, and umbilical diameter to said automatic controller,   automatically sensing number of rotations of said spool,   calculating the adjustment required to maintain the desired motor torque, and   automatically adjusting said adjustment.