Instructions forAnalogue Load Cell Junction Box by Imwithjanet

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									          Instructions for Analogue Load Cell Junction Box
1. General
   As divergence exists in the key material of load cell----strain piece and elastomer,
   and in manufacturing technology, parameters of each load cell are variable. It has
   been found in the study that the unbalance is mainly caused by different
   sensitivity(mV/V) of load cell. Now the potentiometer in junction box is adjusted
   to keep sensitivity(mV/V) of load cell stable, thus maintaining the balance of the
   weighing apparatus.
   BOX Series Analogue Load Cell Junction Box is the instrumental part to adjust
   the balance for large scale weighing apparatus.

2. Type and Nomination
   BOX— five hole junction box, suitable for ground weighing apparatus with four
   load cells. (small size: 174 x 110 x 35)
   BOX— five hole junction box, suitable for ground and vehicle weighing apparatus
   with four load cells. (large size: 240 x 180)
   BOX— seven hole junction box, suitable for vehicle weighing apparatus with six
   load cells. (large size: 240 x 180)
   BOX— nine hole junction box, suitable for vehicle and railway weighing
   apparatus with eight load cells. (large size: 240 x 180)

3.   Technical Quota (adjustment of signal output for load cell)
     A. Stainless-steel shell, and sealed join for input. Endurable and sealed.
     B. High precision resistor and input potentiometer are used to ensure the
        working accuracy and stability.
     C. Welded connection is adopted for load cells and signal cable to ensure
        reliability of the connection. (Connection socket can be ordered)
     D. Code is marked beside welding point for convenience of connection.
     E. Outside Dimension:
         Large box: 245 x 188 x 58            small box: 178 x 112 x 35

4    Power      Skeleton         Diagram                  of              Load   Cell   Junction
     Box:

          +E
                 U1         U2             U3              U4
                       W1             W2             W3              W4


                      J1         J2             J3              J4

         -E
         +IN
         -IN
5.Method of Calculation and Adjustment:
   W: potentiometer, initially for OΩ (if sensitivity mV/V of each load cell is
   consistent, adjustment can be omitted).
                            s
   E: for voltage of meter’ output
   J: for load cell
   U: for voltage at both sides of potentiometer W
                                     s
   N: for displayed figure at corner’ weighing
   Ui=[(Nlarge –Nsmall) ÷ Nsmall] X E(V) ( is natural figure)
   Ui=[(Nlarge-Nsmall) ÷ Nsmall] X E X 1000 (mV)
   For example, 5 ton is weighed on corners of a 30t electronic vehicle weighing
   apparatus, four corners are displayed as:
   N1=5010, N2=5000, N3=5000, N4=4990                 voltage: E=12V
          st
   The 1 point:
   To adjust potentiometer W1 and simultaneously monitor U1 to 48.1mV
   The 2nd and 3 rd points:
   To adjust potentiometers W2 and W3, and simultaneously monitor U2, U3 to
   24.05mV.
     Now adjustment on four corners are completed.

6.Welding Conceptual Diagram:




J0: Correspondently connect to weighing display controller
J1: Correspondently connect to 1# load cell
J2: Correspondently connect to 2# load cell
J3: Correspondently connect to 3# load cell
J4: Correspondently connect to 4# load cell
J5: Correspondently connect to 5# load cell
J6: Correspondently connect to 6# load cell
J7: Correspondently connect to 7# load cell
J8: Correspondently connect to 8# load cell

								
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