A new 122 mm electromechanical drill for deep ice-sheet coring (DISC): 3. Control, electrical and electronics design

The deep ice-sheet coring (DISC) drill developed by Ice Coring and Drilling Services under contract to the US National Science Foundation is an electromechanical drill designed to take 122 mm ice cores to depths of 4000 m. Electronic, electrical and control systems are major aspects of the DISC drill. The drill sonde, the down-hole portion of the drill system, requires approximately 5 kW of d.c. power for the cutter and drill motors and instrumentation. Power is transmitted via a drill cable from a modified, commercially available surface d.c. power supply operating at 1000V to power modules in the sonde instrumentation section. These modules regulate the power to the motors to 300 V d.c. and to lower voltages for the instrumentation and control electronics. Cutter and pump motors are controlled by electronics that include motor controllers. There are 20 distinct sensors in the drill sonde which measure conditions such as hole fluid temperature, motor fluid temperature, drill orientation, etc. On-board electronics facilitate communication of control commands and data between the surface and the drill sonde. Electronics also play an integral part in the operation of surface equipment such as the winch in raising and lowering the sonde in the borehole. Overall control of the DISC drill system is provided by a PC-based supervisory control system that allows the drill operators to monitor and control all aspects of the drilling operation.