W-3. Inertia in the winch drive train
The trawler is going forward dragging a fish net behind. The net is connected by a wire to the winch. The winch drum is being held at zero speed by torque control. Rated torque is applied. Sometimes the net may get stuck and the wire collapse.
Given data (normal operation):
- Empty drum diameter 1 m
- Full drum diameter 1.5 m
- Linear speed at which the cable is to be reeled on the drum 2 m/s
- Force/tension on the cable 100 kN
- Overloads - 50 %
- Vessel grid voltage 690 V
Typical situation is given:
- Speed of the vessel – 5 m/s
- Wire elasticity - 1% (how much it can extend in % before collapsing)
- Wire length 1 km
- Inertia of the drum
- Torque is removed by control system 1 second after the net stuck detection.
- Force on the wire (and torque) increases by 20% right after the net stuck and them increases by 10% for every 0.1% of extension of the wire.
Design drive train so that the wire does not collapse. To find the answer try to dimension the drive train using several gearbox and machine combinations. Check if the wire would collapse in each design variant.
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