Calibration
The T10 has the capability of being calibrated in the field. The electronics in this
weighing system is very stable, and this calibration procedure should rarely need to be
done. However, if the weights are critical, it is advisable that the scale be calibrated
every year or two. If the load cells have been slightly overstressed, or specific errors
have been displayed as described later, it is also advisable to re-calibrate the system
before returning the scale for repair. It may be that recalibration will solve the problem.
Re-calibration may not fix the problem if the weigh bars or load cells have been grossly
overstressed.
To perform the calibration, a known fixed weight must be at hand. Also, if the indicator
is not connected to standard Thunderbird load cells, the capacity of the total system and
the number of load cells in the system must be known. The capacity should be printed
on the label attached to the weigh bar or load cell. The test weight must be a minimum
of 5% of the capacity of the system, and small enough to be able to balance easily on 1
weigh bar or load cell. The maximum test weight is the total capacity of the system
divided by the number of weigh bars or load cells. For example, a 2 tonne system with
2 load cells would have a maximum test weight of 1 tonne. Similarly, a 500kg system
with 2 bars has a maximum test weight of 250kg.
Each weigh bar or load cell is calibrated independently, and they must be removed from
any structure that they’re supporting before calibration starts.
The calibration procedure may be aborted at any time up until ‘donE’ is displayed by
turn the indicator off. The back key may be used to repeat a procedure at any time.
When inputting a value, the up and down arrows may be pressed briefly to increase or
decrease a value, or held down. When held down, the value will increase by 1 unit at a
time until a tens digit changes, and then the value will change by 10 units at a time.
Releasing the key will re-start the procedure.
The procedure is as follows:
1. Press the settings key once, and then press the down arrow key. ‘CAL-‘ will be
displayed. Press OK to continue, or the settings, down arrow or weigh key to
exit. Press the back key to show the system capacity again.
2. If non-standard Thunderbird load cells or older Thunderbird load cells are used,
the system capacity needs to be entered. Otherwise go to step 4. Use the up
and down arrow keys to input the system capacity and then press OK.
3. If non-standard Thunderbird load cells or older Thunderbird load cells are used,
the number of load cells needs to be entered. Otherwise this step is skipped.
Use the up and down arrow keys to select the number of load cells and then
press OK.
4. If there are 2 load cells in the system ‘bAr1’ will be displayed and ‘zero weight’
will flash, otherwise go to step 5. Press tare, weigh or OK to continue.
5. ‘rdY?’ will be displayed and ‘zero weight’ will be flashing. Remove any weight
from load cell 1 (the load cell plugged into the left hand socket) and then press
tare, weigh or OK. If there is only one load cell, pressing back will exit the
calibration procedure.
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