Testing Load Cell - KERN HFC Service Manual

11.3

Testing Load cell

For testing load cell, remove power from the system, and disconnect the PCB from
the Load cell
Physical Test:
 Check the moisture, or foreign material inside.
 Check load cell surface badly rusted or corroded
 Check the strain gauge areas become compressed
 Check any physical damage (body bent or twisted) to the load cell
 Check load cell cable, all leads are connected, any cut, splits or tears.
 Check load cell for proper input and output resistances
Electrical Test:
Use an accurate multimeter to check the ohms
Load Cell Connections
Measuring Points
Red (+ Exc) to Black ( –Exc)
Green (+Sig) to White ( –Sig) 350Ω ±3Ω
Leakage Resistance
 Check each of the load cell wires to the load cell cable screen.
 Check each of the load cell wires to the load cell body.
These readings should be greater than 1000mΩ or OL.
If this reading is less than 1000 mΩ, then this load cell has leakage between the
internal circuit and the load cell body or cable screen
Zero Balance
 Connect the load cell to a stable DC source of between 5 to 10V
 Connect multimeter to mV and connect to the load cell signal wires
 The meter should read 0.00mV ± approximately 1 % of full load.
If the output reads greater than ±10% of full scale capacity, then the load cell will
require replacement.
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Signal + Green
Supply + Red
Signal - White
Supply - Black
Shield
Resistance
409 ±6Ω
HFC-SH-e-1510