Tecnetics Industries Tecweigh 20, Operation Manual

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7.01 Apply Power to the System
Assuming that all the entered Parameters are correct and all the equipment is installed properly,
the scale must now be calibrated. Without calibration, the scale will only approximate the RATE.
First, however, on scales with LVDT(s) (
L inear V oltage D ifferential T ransformer), a procedure
needs to be performed to verify that the LVDTs are in alignment. Use one of the following two
sections, depending upon whether the scale has a SC200 or SC400 signal conditioner, to verify
(and re-align if necessary) the LVDT alignment.
Now turn on the conveyor, power up the WP20, make sure the belt is clean, and let the entire
system run for at least half an hour (longer in colder environments) so it attains temperature
stability. If the WP20 displays a "Scale Data Error", there’s a communications problem between
the scale (the signal conditioner) and the WP20. This problem must be corrected before
continuing. Consult Section 9.08, “scale data error”, for troubleshooting tips.
7.02 LVDT Alignment for Scales with a SC400 Signal Conditioner
(WY10, WY10HD, WY20 scales Only)
The WY10 and WY10HD have two LVDTs, while the WY20 has four LVDTs. Alignment of the
LVDTs is critical for scale accuracy. The LVDTs were aligned at the factory, but it must be
verified that they are still in alignment after shipping and installation. Turn the belt off, leave the
MS20 on and remove both side covers from the scale. On the SC400 PCB, DIP switches SW3
and SW4 are used in the alignment procedure (see the figure below). First verify that SW3 and
SW4 are set to the positions shown on the first or second lines in the following chart depending
on the particular scale at hand. Next, to verify proper alignment, connect a DC voltmeter across
the test points (again see the figure). If the voltage is 2.50 +/- 0.02 VDC, the LVDTs are
sufficiently aligned and move on to the next section, however, if the voltage is outside the stated
range, continue as follows.
CHAPTER 7 – CALIBRATION