Introduction
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3
Weighed Structure Grounding
Using a 10 gauge solid or braided wire or braided grounding strap, connect the load cell upper support plate with the lower
support plate, then connect all the lower plates to a single earth ground. Once installed, accumulated electrostatic charges are
discharged to the ground without going through or damaging the load cells. Failure to implement a proper grounding system
may not affect the operation of the weighing system; however, this does not rule out the possibility that the cells and connected
SCT Weight Transmitter may become damaged in the future. Do not ground using metal parts contained in the weighed
structure.
Figure 1-1. Installation Recommendations
1.5 Load Cells
1.5.1 Load Cell Input Test (Quick Access)
1. From the weight display, press for three seconds.
is displayed.
2. Press
. The response signal of the load cell is displayed, expressed in mV with four decimals.
3. Press three times to exit test mode.
1.5.2 Load Cell Testing
Load Cell Resistance Measurement (Use A Digital Multimeter)
• Disconnect the load cells from the instrument and check that there is no moisture in the load cell junction box caused by
condensation or water infiltration. If so, drain the system or replace it if necessary.
• The value between the positive signal wire and the negative signal wire must be equal or similar to the one indicated in
the load cell data sheet (output resistance).
• The value between the positive excitation wire and the negative excitation wire must be equal or similar to the one
indicated in the load cell data sheet (input resistance).
• The insulation value between the shield and any other load cell wire and between any other load cell wire and the body
of the load cell must be higher than 20 Mohm (megohms).
Load Cell Voltage Measurement (Use A Digital Multimeter)
• Remove the weight of the scale from the load cell to be tested.
• Make sure that the excitation wire of the load cell connected to the instrument is 5 Vdc +/- 3 percent.
• Measure the millivolt signal between the positive and the negative signal wires by directly connecting them to the multi-
meter. Make sure it reads between 0 and 0.5 mV.
• Apply load to the load cell and make sure that there is a signal increment.
If one of the above conditions is not met, please contact Rice Lake Weighing Systems Customer Support for
assistance.
Ground plate used to
continue ground
Structure used to
continue ground
IMPORTANT
