Measurement Technology NW
LCI-90 Operator Manual
Page 34
5.7
Wrap Angle (single-input configurations)
To set the correct wrap angle for a single-axis load-pin, press
CALB
to display the main
2.0 CALIBRATION
menu. Select Item 4 and press
ENT
to activate the edit keys. Use
the
INCR
,
DECR
and
keys to change the value. Press
ENT
to save the new value or
ESC
to cancel the changes. Note that Sensor Angle replaces Wrap Angle when the input
configuration is set to
2-AXIS
mode, and neither angle is displayed in
SUM
mode.
2.0 CALIBRATION
1
TENSION (THREE METHODS)
2
TENSION TARE
OFF
3
SHUNT CAL
OFF
>
4
WRAP ANGLE
120 DEG
5
PAYOUT SCALE
2.800 P/FT
6
PAYOUT PRESET
150 FT
5.7.1 Wrap angle adjustments
The LCI-90 has the ability to correct for variations in sheave geometry by allowing
the user to specify the wrap angle. (See §11 for a definition of this angle, and a table
showing the effect it has on the measured tension.) The wrap angle correction only
applies to fixed sheave angle geometries; if this angle varies (for example, a sheave
mounted on a movable boom, or a load that swings through an arc), a dual-axis load
pin (§5.8), or a direct line-tension sensor is required to get accurate results.
In practical situations the wrong wrap angle can lead to a 40-50% error in the readout
unless the LCI-90 is calibrated using the two-point live method described in §5.4.2.
The two-point method automatically adjusts the scale and offset values to compen-
sate for fixed wrap angles. For maximum accuracy with live calibrations (or for
tension measurements that do not involve wrap angle), this item should be set to 120º
(the factory default value).
