Atlas Copco PowerMACS 4000, User Manual

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Tightening
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Function: This check measures the angle from the yield point to the end of the step. The measured
angle, YP Angle, is checked to be within the limits Yield Angle low and Yield Angle high. If
the value is outside an error is reported.
The search for the yield point starts then the torque has reached the level Torque start.
From this point the gradient, i.e. the ratio of torque vs. angle, is calculated. During the step
the maximum gradient value is stored. The yield point is found then the calculated gradient
is less than DIFF * Maximum gradient. The DIFF value is specified as a percentage of the
maximum gradient.
The angle to use as end angle is controlled by the parameter Stop condition. There are
three different angles that can be used. Final angle, F, is the last measured angle in the
step. Shut off angle, SO, is the angle at the shut off point and Peak angle, P, is the highest
angle reached during the step. For more details see Check Angle.
The gradient calculation is done in the same way as in the Gradient Restriction. The check
compares the filtered torque values Angle distance apart to find the gradient. The torque is
filtered with a sliding average over the angle No degrees. See also the Gradient Restriction
for more details.