The recently developed Hardsuit thruster pack allows the Hardsuit to work at various depths in the water column, and increases mobility greatly. The thrusters attach directly to a specially made waist ring and can be installed quickly onto the suit.

The two thruster units can be mounted on the port and starboard side of the suit at the waist area, just aft of the arms. Each thruster unit consists of a 1.5 HP motor driving two variable pitch propellers.

The complete thruster pack consists of the auxiliary power unit, the power control unit on the surface, and the suit mounting ring. The suit mounting ring consists of the power supply receptacle, mixer board receptacle, the propulsors, and the internal control system.

Auxiliary Power Unit (APU)

The APU supplies the correct type of power for the thruster units and control systems. The thrusters operate at 440 volts and 400 Hz. Using such a high voltage and frequency allows for the use of very small electric motors and small diameter umbilical. The APU produces 5 KVA of power and requires 220 or 440 volt, 3 phase, 60 Hz supply and draws either 10 or 20 amps.

The complete system is protected by line insulation monitors (LIMs). The LIMs act as circuit breakers and will shut down the system with a current differential of 20 milli amps. The APU has LIMs built in.

Power Control Unit (PCU)

The PCU accepts power from the APU. The PCU is located on the surface and contains the distribution system, switches, amp meters, and volt meters for the various systems. The PCU accepts 3 phase power of either 208 or 440 volts at 400 Hz. If the power supplied is 208 volt, it is boosted up to 440 volts by the PCU. The 440 volt power is used to drive the thrusters while the 220 volt power is used for instrumentation and to power the control system.

The instruments of the PCU consist of amp and volt meters for the motors and auxiliary system, on/off switches for the APU motor and the APU generator, as well as gauges showing volts out, current, and frequency. There are also on/off switches for the thruster motors and gauges indicating volts, amps, and operating hours. The PCU also contains two LIMs for circuit protection. The LIMs sense insulation breakdown at a sensitivity of 5 milli amps and a response time of less than 20 milli seconds.

Power from the PCU then goes down the umbilical to the Hardsuit. A basic umbilical would be 1/2 inch in diameter and consist of three 14 gauge wires, two 16 gauge wires, one 22 gauge wire, and a twisted shielded pair. The power travels down the umbilical to the power supply receptacle mounted on the outside of the Hardsuit, then goes from the power supply directly to the thruster motors. The power supply also supplies ± 15 volts D.C. for underwater lights and television cameras.

The power supply also supplies power to the mixer board which is also mounted externally on the Hardsuit. The mixer board supplies the power to control the pitch on the variable pitch propulsion system. The mixer board also supplies power to the foot control system which controls left, right, forward and aft movement, the thumb switch with controls vertical movement, and power to the depth meter (LCD read out).