Chinese
Spanish
Russian
Portuguese
French
German
Indonesian
Thai
Vietnamese
Arabic
Italian
Turkish
Polish
Japanese
Load cell cable shielding and grounding should be investigated when a weight reading changes with a motor, contactor or nearby equipment. First establish whether the disturbance is electrical or mechanical. Vibration transmitted into the scale can look like electrical noise, and changing shield connections will not remove a genuine change in force.
Record when the disturbance occurs
Compare readings under controlled machine states and retain the original settings. Note whether the symptom follows a drive starting, a cable moving, rain or a temperature change. Where permitted, inspect the instrument's unfiltered input as well as the displayed weight. Heavy filtering can conceal the timing needed to locate the source.
| Symptom | Checks to make | What not to assume |
|---|---|---|
| Drive-related | Compare routing, bonding, signal behavior and physical vibration when the drive operates. | A shared start time does not prove that the interference enters through the cable. |
| Movement-related | Inspect strain relief, connector condition and cable force on the sensor. | A moving cable can create electrical intermittency or a real mechanical load. |
| Weather-related | Check entries, seals, moisture and temperature-dependent changes. | A heavier shield will not repair a wet terminal or damaged cable jacket. |
| After extension | Compare cable specification, sense wiring and excitation at the documented reference point. | Matching wire colors does not establish equivalent resistance or connections. |
Specify the cable, not only the word shielded
METRAVON MV-WA0011 is listed as a single-shielded weighing signal cable. MV-WA0012 is a sheathed, double-shielded version. Those descriptions identify construction choices, but do not establish a universal maximum length, conductor resistance or termination method.
For a quotation, provide the wiring diagram and installed route. Confirm conductor count and cross-section, resistance, capacitance, shield arrangement, outside diameter and any connectors. Include temperature, chemical exposure, repeated movement and required bend conditions. Do not infer suitability for a cable carrier or burial from the fact that a cable carries a weighing signal.
Load cell cable shielding and grounding need a system drawing
Identify excitation, signal, sense, shield and protective-bonding conductors separately. Check whether the sensor cable shield is connected internally to the body and how the instrument manufacturer expects it to terminate. A metal gland or connector can create a connection that is absent from an incomplete wiring sketch.
There is no universal instruction to connect every shield at one end or at both ends. The correct arrangement depends on the instrument's EMC design, bonding, interference frequencies and any hazardous-area requirements. Follow the documented installation design and verify the actual connections at both ends.
Protective earth and a signal reference have different functions. Never remove protective earth to make a reading quieter. Differences in equipment potential require a properly designed bonding or isolation solution, assessed by a qualified electrical specialist, rather than an improvised shield disconnection.
Route low-level measurement cables separately from motor and drive-output wiring where the installation permits. Keep exposed, untwisted signal tails short according to the connector instructions and maintain the specified shield termination. Do not promise an exact noise reduction from shielding alone.
Understand what six-wire sensing can compensate
Sense conductors allow compatible electronics to monitor excitation at the designated remote point. They are not additional signal conductors, and they do not cancel mechanical error or electromagnetic pickup.
For a junction-box installation, confirm whether the reference point is at the box or at individual bridges. Compensation of the instrument-to-box cable does not necessarily compensate each sensor's lead. The junction box selection guide explains why the adjustment and sense circuits must be reviewed together.
Cutting or extending a four-wire sensor cable can change excitation-related errors. Check the cell and instrument instructions before altering it, then verify the installed calibration. Adding two wires to an existing cable does not create remote sensing unless they connect to the correct electrical points and the electronics support it.
Change one cause at a time and verify the result
Use an approved troubleshooting procedure to inspect wiring, excitation and signal behavior. Isolate equipment before continuity or resistance tests, and use test methods compatible with connected electronics. Do not apply an insulation-test voltage to an amplifier or interface without authorization from its documentation.
After a correction, repeat the operating state that originally caused the disturbance. Verify zero stability, a known applied load and the response needed by the process. A quiet unloaded display is insufficient if the changed routing or filter affects loaded measurement or response time.
Keep the final cable schedule, shield connections and before-and-after observations. For outdoor systems, have surge protection and bonding evaluated as part of the installation; a shield braid is not a substitute for a coordinated surge path.
Cable installation questions
Q1. Is double shielding always preferable?
It can be appropriate for a specified interference problem, but its benefit depends on construction and termination. It does not repair loose terminals, incorrect sense wiring or mechanical vibration. Select MV-WA0012 from the actual route and electrical requirements, not the number of shields alone.
Q2. Can the same cable colors be used as the wiring instruction?
No. Map colors to functions using the exact sensor and instrument diagrams. Preserve that mapping at junction boxes and connectors; different manufacturers or revisions may use different assignments.
Q3. What information helps investigate unstable readings remotely?
Send a circuit diagram, cable route photographs, length and specification, grounding details, equipment models and a trace showing when the disturbance occurs. Include recent repairs or extensions in the METRAVON support enquiry rather than asking for a replacement cable without the installation history.
Summary
Diagnose the disturbance before selecting a cable or altering shield connections. Document excitation, signal, sense and protective bonding as distinct functions. Validate the repair under the operating conditions that caused the original problem.
