CST Load Cell Wiring & Troubleshooting 2

Question 1

What is the typical color code for the excitation positive (+EXC) wire in a standard 4-wire load cell cable?

Accepted Answer

Red

Answer

In most standard load cell color conventions, red is used for the excitation positive (+EXC) lead.

Question 2

A technician measures 0 mV output from a load cell under full rated load. Which fault is most likely?

Accepted Answer

Open excitation circuit

Answer

An open excitation circuit removes the bridge supply voltage, resulting in zero output regardless of applied load.

Question 3

When wiring multiple load cells in a parallel junction box, what must be matched between cells to ensure accurate summing?

Accepted Answer

Input impedance of each load cell

Answer

Matching input impedance ensures equal current distribution across parallel-connected load cells for accurate summing.

Question 4

What does a negative mV/V output reading indicate when a load cell is under a compressive load that should produce a positive reading?

Accepted Answer

Signal wires are reversed

Answer

A negative output when positive is expected means the signal+ and signal− leads have been swapped.

Question 5

Which instrument is most appropriate for measuring the zero balance output (offset) of a load cell in mV?

Accepted Answer

Precision digital multimeter

Answer

A precision digital multimeter with mV resolution is the correct tool for measuring the small DC offset voltage of a load cell at zero balance.

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