Drive set-up Basic drive set-up and span position limit switch points The following is a guideline for setting the variable drives and limit switches. These set points are intended for a starting point and not an absolute. Thyristor drives 1. The drives are normally set for a 25% slip with the secondary resistor bank 2. The full or 100% speed should be at 75% of the full synchronous of the motor, as an example this would be 675rpm of a 900 rpm motor 3. The reduced or 50% speed should be at 37.5% of the full synchronous of the motor, as an example cases this would be 337 rpm of a 900 rpm motor 4. The creep speed or seating speed should be based on the speed at which the span needs to seat, (the softer the batter) , in many cases this would be 120 rpm, of a 900 rpm motor. 5. The reduced toque or reduce current during the seating sequence should be less the 100% of the motor F.L.A. 6. The ramp time should be set at 10 seconds (full ramp available). The full ramp time will aid in minimizing the large start-up current draw. 7. Speed control should be set soft to allow the span to float in speed. This will prevent large surges of current during span motion. There will be large current surges during the start of the span motion. Limit switch set points 1. Low speed check points should be set as to allow for an emergency stop of the span without hitting the full open or full close stop. This point should check to see that the span is slowing done, from the slowest run speed to seating speed. (One half of the reduced, 50% speed, or 25% speed 160r.p.m.) 2. High speed monitoring should be set to stop span before a speed is reached that will cause damage. This point is normally set at 110% of full speed ( a round number of 750 rpm is normally used ) 3. The near open and near close deceleration points should be set to allow the span to decelerate below the speed check reference rpm. 4. The near open and near close pilot lights should be set to the same points as the decelerate points. 5. The full open point should be set to allow the span to clear the pier without hitting the full open bumper stop. The switch should be set in the opening direction only. 6. The full close or seated switch should be set when the span is moving in the seating direction only.
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