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10.2
C
ALIBRATION
10.2.1
How does the calibration work
Calibration is performed by lifting a known weight equal to the maximum that
can be measured on the range selected.
The machine will tell you which weight is required see section 7.
The cold bump pull cartridge uses a special hook designed to lift the weight on
the centre-line of the transducer. This also minimises the tendency for the weight
to swing.
The shear calibration uses a special jig so that the load can be applied in precisely
the same manner as the test load.
On the BS5KGHS jig, a ratio of 4:1 is used to apply a load equal to the weight
hung.
After the weight is positioned, the calibration sequence is started.
The machine will lift and lower the weight once without making any
measurements, however there is a check made that the reading is steady.
If there is too much vibration through the machine, then after 20 seconds the
weight will be lowered and the calibration failed.
On cold bump pull calibration, after the weight is lowered for the first time, the
hook must not be touching the wire or the weight, as this is when a zero weight
reading is taken for reference.
If the wire on the weight is bent, the weight may lift at an angle. This may lead to
an incorrect reading, so carefully straighten the wire and try again.
After the first lift and lower, there could be from one to ten more depending on
how your engineer has configured the calibration.
If there are more than one additional lift, then an average is taken of the readings,
and the spread of the readings is checked to ensure they are consistent.
This results in a more reliable calibration.
Calibration can be set to happen at regular intervals.
Each range on each cartridge is time-stamped when calibrated, and this date is
written into the cartridge memory.
The machine automatically checks the current date against the calibrated date for
the range chosen.
Your engineer sets the interval between calibrations.
Once the interval has elapsed, then either a warning is issued, or the cartridge is
disabled until calibration is completed - depending on your engineering settings.
