Vibration sensors and transmitters: 50 selection, application and maintenance questions

A vibration sensor measures acceleration, velocity or displacement over a defined axis and frequency band. It may output a dynamic waveform, integrated quantity or overall metric; these forms are not interchangeable. The principle explains signal generation; it does not establish the range, accuracy, materials or approvals of every model. Review the physical principle and the application limits separately.

Verification: Confirm "Whether the objective is acceleration, velocity, displacement or an overall alarm metric" and assess "Different vibration quantities and RMS/peak definitions cannot share one threshold blindly" against the actual application. Record the complete model and document revision used.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

Define the quantity to be accepted before selecting a display unit. A vibration sensor measures acceleration, velocity or displacement over a defined axis and frequency band. It may output a dynamic waveform, integrated quantity or overall metric; these forms are not interchangeable. For "Whether the objective is acceleration, velocity, displacement or an overall alarm metric", document output definitions and conversion or compensation conditions; displaying a value does not make it a direct measurement under all conditions.

Verification: Document the process objective, units and reference conditions. Check "Using a fixed RMS-to-peak factor for arbitrary waveforms" and list separate inputs and acceptance methods for calculated results.

适用边界：Using a fixed RMS-to-peak factor for arbitrary waveforms

Prepare at least these five input groups: Whether the objective is acceleration, velocity, displacement or an overall alarm metric; Required band, speed, transients and maximum shock; Measuring direction, machine structure and mounting method; IEPE, charge, voltage, current or digital interface needs; Temperature, cabling, acquisition and diagnostic objective. Mark unknown items for confirmation instead of substituting a normal point or an assumed default for all conditions.

Verification: Have process, instrumentation and purchasing roles agree the inputs, particularly "Required band, speed, transients and maximum shock". Resolve missing evidence before requesting application confirmation.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

Select the range from actual operating conditions and permissible error, then check extremes and installation constraints. For this family: Different vibration quantities and RMS/peak definitions cannot share one threshold blindly Nominal size or maximum equipment rating need not equal the useful measuring interval.

Verification: List minimum, normal, maximum and abnormal conditions. Check "Measuring direction, machine structure and mounting method" against the documented performance envelope.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

No. Low-end usability depends on the principle, available signal and error mechanisms. Mounting coupling and sensor bandwidth constrain high-frequency response More display digits, software scaling or a stated turndown cannot remove the original noise or installation error.

Verification: Obtain error definitions and limits at the actual low operating point. Use "Amplitude mismatch: check units, RMS/peak, band and location" to investigate bias instead of comparing only percent-of-full-scale values.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Use the complete measured object and actual exposure, rather than a material name alone. IEPE, charge, voltage, current or digital interface needs Avoid this family-specific misuse: Connecting IEPE directly to a process-current input For non-wetted equipment, assess loads, target materials, signals and environmental compatibility instead.

Verification: List the actual contact or loading parts, seals, insulation and cleaning conditions. Have the responsible parties assess "IEPE constant-current excitation is not a 4–20 mA process loop".

适用边界：IEPE constant-current excitation is not a 4–20 mA process loop

Normal measurement, temporary excursions and survival limits are different requirements. IEPE constant-current excitation is not a 4–20 mA process loop Start-up, cleaning, impacts, power interruption or abnormal environments can determine the necessary construction and protection.

Verification: Complete the worst-case conditions using "Temperature, cabling, acquisition and diagnostic objective" and check "Condition-monitoring output is not automatically machinery protection or safety output". Separate continuous operating limits from temporary limits in the specification.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

Not without assessment. Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks. The installed system also includes object, mounting, signal conversion, environmental and reference effects. Derived results additionally depend on the relevant input uncertainties.

Verification: Agree actual test points, installation conditions and the acceptance reference. Check "Choose a stiff point near the relevant bearing and mark direction" and document the system error or uncertainty basis.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

A stable indication and fast change detection involve a trade-off; filtering cannot repair incorrect installation or real process variation. Unexpected high-frequency peaks: inspect mounting resonance, cable contact and real impacts Review the complete chain when fast response matters, not merely the display refresh rate.

Verification: Define the shortest relevant event and acceptable delay. Check "Match excitation and acquisition range and allow specified settling" and verify local output, display and receiving-system response using a controlled change.

适用边界：Comparing high-frequency values without validating magnetic or adhesive mounting

Typical contexts include: Rotating-machine bearing-housing monitoring; Machine shock and vibration trending; Dynamic tests within a specified frequency band. Similar application labels do not establish equivalent conditions. In particular, assess "Condition-monitoring output is not automatically machinery protection or safety output" before relying on another installation as proof.

Verification: Select the nearest application and compare "Whether the objective is acceleration, velocity, displacement or an overall alarm metric" and "Temperature, cabling, acquisition and diagnostic objective". Obtain written confirmation where published application limits are exceeded.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

Translate required functions, performance and physical interfaces into verifiable options. Quantity, frequency band, axis and amplitude definition; Sensitivity, maximum input and mounting interface. Options affecting suitability or supply scope should be explicit; terms such as standard or same as existing are insufficient.

Verification: Check the complete order code and selection sheet, especially "Measuring direction, machine structure and mounting method". List accessories, documents, calibration and delivery boundaries separately.

适用边界：Using a fixed RMS-to-peak factor for arbitrary waveforms

Choose a stiff point near the relevant bearing and mark direction The installation drawing must match the available space and process or mechanical structure. Access for fitting and servicing should be established before delivery.

Verification: Review a dimensioned, oriented site drawing. Use "IEPE, charge, voltage, current or digital interface needs" and "IEPE constant-current excitation is not a 4–20 mA process loop" to confirm connections, support, removal access and safe isolation.

适用边界：IEPE constant-current excitation is not a 4–20 mA process loop

Prepare contact surface, fastening and cable strain for the mounting method Supporting conditions are part of the measurement system. Matching mechanical connections or signal names alone do not establish power, I/O, grounding or configuration compatibility.

Verification: Confirm "Excitation, bias, output and acquisition compatibility" and "Filtering, integration, overall metrics and alarm algorithm" against actual terminals, loops and receiving-system settings.

适用边界：Connecting IEPE directly to a process-current input

Check identity, installation and basic conditions first, then status, output and process response. Match excitation and acquisition range and allow specified settling Preserve original evidence for unexplained anomalies instead of concealing them with zero or factor adjustments.

Verification: Record factory settings and initial status. Investigate "No valid waveform: check excitation, bias, cable and range" step by step and change parameters only after identifying the cause and using an authorised procedure.

适用边界：Comparing high-frequency values without validating magnetic or adhesive mounting

No. Establish the represented object and reference conditions: Quantity, frequency band, axis and amplitude definition. Electrical equipment also needs loop type, scaling, failure behaviour and protocol details checked. Mechanical indicators require clear boundaries between indication and remote-transmission accessories.

Verification: Check the receiving-system variable against "Whether the objective is acceleration, velocity, displacement or an overall alarm metric" and verify limits, units and abnormal states with the actual equipment. Record wiring, configuration and end-to-end checks against "Prepare contact surface, fastening and cable strain for the mounting method".

适用边界：Connecting IEPE directly to a process-current input

Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks. The report should identify the delivered instrument, measured quantity, conditions, method and results. A general conformity certificate does not establish performance for every option or operating condition.

Verification: Check serial number, points, units, reference equipment and traceability. Compare "Required band, speed, transients and maximum shock" with the calibrated conditions and agree separate acceptance where they differ.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Verify quantity, frequency band and output with a suitable vibration reference Agree criteria before testing, including range, conditions, error definition and treatment of anomalies. Similar-looking readings or an unsuitable portable reference are not sufficient acceptance evidence.

Verification: Choose an appropriate reference using "Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks.". Record "Whether the objective is acceleration, velocity, displacement or an overall alarm metric" and test conditions; investigate "Amplitude mismatch: check units, RMS/peak, band and location" before deciding on rework or recalibration.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Define why the standard supply is insufficient, the required verification and the responsible parties. Condition-monitoring output is not automatically machinery protection or safety output; Treating housing absolute vibration as relative shaft vibration. Additional materials, construction, documents or tests depend on actual requirements.

Verification: Attach "Temperature, cabling, acquisition and diagnostic objective" and the deviations. Obtain technical confirmation, additional charges, delivery conditions and acceptance methods; unknown requirements must not be assumed satisfied.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

No valid waveform: check excitation, bias, cable and range Distinguish the actual measured condition from device-state and readout or transmission faults. Do not immediately interpret missing data as sensor failure or a zero process value.

Verification: Under appropriate safe isolation, check "Prepare contact surface, fastening and cable strain for the mounting method". Compare local and receiving-end status and record when the fault appeared.

适用边界：Using a fixed RMS-to-peak factor for arbitrary waveforms

Unexpected high-frequency peaks: inspect mounting resonance, cable contact and real impacts Compare independent process evidence and raw signals before deciding whether installation, interference or equipment is responsible. More filtering can hide a real abnormal event.

Verification: Keep conditions comparable and record correlation with process or equipment events. Check "Choose a stiff point near the relevant bearing and mark direction" and change one factor at a time.

适用边界：Comparing high-frequency values without validating magnetic or adhesive mounting

Amplitude mismatch: check units, RMS/peak, band and location Systematic bias can arise from units, reference conditions, configuration, installation or the reference method. An unexplained correction can move one operating-point error to other conditions.

Verification: Align quantities, time bases and units first. Review the reference using "Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks." and confirm that "Required band, speed, transients and maximum shock" matches the configuration.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Low-frequency drift: check integration, coupling cutoff and baseline noise Establish a genuine, stable reference condition that meets the method requirements before considering adjustment. Some instruments have no freely adjustable site zero.

Verification: Check "Match excitation and acquisition range and allow specified settling" and "Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks." and retain before-and-after results. If the conditions cannot be established, remove external effects or use a qualified service.

适用边界：Comparing high-frequency values without validating magnetic or adhesive mounting

Intermittent overload: check shock peaks, excitation headroom and connectors Intermittent faults need correlated event records, not just a normal display after recovery. Review alarm settings, communication status and actual process abnormalities separately.

Verification: Retain time, status codes, raw trends and the contemporaneous "Temperature, cabling, acquisition and diagnostic objective". Compare "Prepare contact surface, fastening and cable strain for the mounting method" and "Match excitation and acquisition range and allow specified settling" to locate the failing link.

适用边界：Treating housing absolute vibration as relative shaft vibration

Repeated failures warrant a common-cause assessment. Treating housing absolute vibration as relative shaft vibration If the external conditions remain unchanged, an identical construction or installation can experience the same failure again.

Verification: Summarise failed parts, service time and "Temperature, cabling, acquisition and diagnostic objective". Check "Choose a stiff point near the relevant bearing and mark direction" and "IEPE constant-current excitation is not a 4–20 mA process loop" and establish corrective action before selecting repair or redesign.

适用边界：IEPE constant-current excitation is not a 4–20 mA process loop

Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks. A comparison identifies differences; adjustment changes indication or parameters; calibration establishes a reference relationship under stated conditions. They are not interchangeable claims.

Verification: Define what performance and evidence must be established, using conditions relevant to "Required band, speed, transients and maximum shock". Retain original and adjusted results, references and responsibility records.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

The same basic model does not establish identical options, software, calibration or accessories. Filtering, integration, overall metrics and alarm algorithm; Environmental, calibration and protection-duty evidence. Previous system operation does not remove the need to verify a replacement.

Verification: Compare full order codes and revisions. Recheck critical points, failure states and interfaces using "Verify quantity, frequency band and output with a suitable vibration reference" before handover.

适用边界：Treating housing absolute vibration as relative shaft vibration

No. Different vibration quantities and RMS/peak definitions cannot share one threshold blindly Maximum values usually relate to particular options and conditions. Temperature, load, pressure, materials, speed or signal conditions may constrain one another.

Verification: Review "Measuring direction, machine structure and mounting method" and "Temperature, cabling, acquisition and diagnostic objective" together. Obtain confirmation for the combined conditions instead of assembling unrelated maxima from separate pages.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

No. No valid waveform: check excitation, bias, cable and range Indication, measurement and transmission have distinct possible failure modes. Also consider "Using a fixed RMS-to-peak factor for arbitrary waveforms"; establish the actual process condition independently.

Verification: Check available status or failure indications and "Excitation, bias, output and acquisition compatibility". For interlocks, follow the complete safety design rather than substituting a zero value for diagnosis.

适用边界：Using a fixed RMS-to-peak factor for arbitrary waveforms

No. Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks. Test points and directions must reflect the working interval, relevant error mechanisms and acceptance purpose. Multiple points, reversal or load tests depend on the method.

Verification: Define acceptance coverage against "Required band, speed, transients and maximum shock" and include critical operating points. Mark conditions outside the tests as unverified.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Not necessarily. Options should serve the required objective; excess configuration can add cost, complexity or incompatibility. Mounting coupling and sensor bandwidth constrain high-frequency response; Connecting IEPE directly to a process-current input. Establish essential requirements before comparing optional benefits.

Verification: Document the objective in "Whether the objective is acceleration, velocity, displacement or an overall alarm metric" and why "Quantity, frequency band, axis and amplitude definition" is needed. Compare performance at actual working points rather than one headline metric.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Not independently of risk and history. Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks. Intervals depend on applicable law or contract, conditions, drift, maintenance and failure evidence. Generic advice cannot replace mandatory requirements.

Verification: Use "Low-frequency drift: check integration, coupling cutoff and baseline noise" and "Treating housing absolute vibration as relative shaft vibration" to establish and review an initial plan. Retain the justification and approval for interval changes.

适用边界：Treating housing absolute vibration as relative shaft vibration

Physical fit is insufficient. Sensitivity, maximum input and mounting interface; Excitation, bias, output and acquisition compatibility. Matching, materials, signals, calibration and approval boundaries can change with the combination.

Verification: Check the complete combination against "Prepare contact surface, fastening and cable strain for the mounting method" and obtain compatibility and acceptance evidence. An unconfirmed assembly must not be described as an approved system.

适用边界：Connecting IEPE directly to a process-current input

Check the exact order configuration and valid documents rather than a series name. Environmental, calibration and protection-duty evidence "Condition-monitoring output is not automatically machinery protection or safety output" also matters; certificates, installation conditions and restrictions together define suitability.

Verification: Obtain certificate identifiers, covered models and special conditions and match them to the site. Similar names do not grant functional-safety or legal-metrology approval.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

Establish the chain from quantity definition and application limits through configuration, mounting, reference and operating status. Verify quantity, frequency band and output with a suitable vibration reference A normal indication or brochure alone cannot demonstrate continuing system reliability.

Verification: Put "Whether the objective is acceleration, velocity, displacement or an overall alarm metric", "Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks." and "Intermittent overload: check shock peaks, excitation headroom and connectors" into the technical, acceptance and maintenance records, with responsibility for reviewing excursions.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

Possibly, after a full configuration and application comparison. A basic model name or matching output is not proof of equivalent replacement. Quantity, frequency band, axis and amplitude definition; Sensitivity, maximum input and mounting interface; Excitation, bias, output and acquisition compatibility. Record conclusions on material differences.

Verification: Provide the original full order code, data sheet and site conditions. Check "Filtering, integration, overall metrics and alarm algorithm" and "Environmental, calibration and protection-duty evidence" and obtain the necessary test and approval evidence before replacement.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

Base the decision on project compliance and documented delivery or service, rather than a slogan. "Whether the objective is acceleration, velocity, displacement or an overall alarm metric" and "Different vibration quantities and RMS/peak definitions cannot share one threshold blindly" are important family-specific checks. Claim only benefits supported by the offered product documents and written commitments.

Verification: Request the proposed configuration matching "Quantity, frequency band, axis and amplitude definition", test evidence and delivery/service terms. Do not infer unverified performance, approvals, origin or service life.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

Use identical conditions and supply boundaries. Quantity, frequency band, axis and amplitude definition; Excitation, bias, output and acquisition compatibility; Environmental, calibration and protection-duty evidence. Quotes with different ranges, compensation, accessories or calibration scope can conceal material differences.

Verification: Compare "Required band, speed, transients and maximum shock", "Mounting coupling and sensor bandwidth constrain high-frequency response" and mounting/acceptance conditions. Separate demonstrated, unverified and inapplicable items; do not claim unproven overall superiority.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Compare complete supply and use-cycle costs, not only the main instrument price. Choose a stiff point near the relevant bearing and mark direction; Vibration calibration must state quantity, axis, frequency, amplitude and mounting; one sensitivity point does not establish the whole bandwidth, and waveforms and overall metrics need separate checks. List the actual installation, supporting equipment, calibration, consumables, downtime and service requirements without assuming any brand is always cheaper.

Verification: Use the same "Quantity, frequency band, axis and amplitude definition" configuration and "Temperature, cabling, acquisition and diagnostic objective" boundary. Separate equipment, accessories, commissioning and maintenance responsibilities and retain a traceable comparison.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

No. They are different quantities. Single-frequency sinusoids permit angular-frequency conversion, but broadband and impact signals require defined bands and integration.

Verification: Check units, band and waveform and record integration and high-pass settings before comparison.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

That relationship applies to a sinusoid under the relevant definition, not every waveform. Impulsive, harmonic or random vibration can have different crest factors.

Verification: Retain the waveform and definitions and compute RMS, peak and peak-to-peak over a stated window.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

IEPE uses specified constant-current excitation with a dynamic voltage on a bias. Process-current input power and scaling are different despite similar current numbers.

Verification: Verify excitation, DAQ IEPE capability, bias headroom and cable loading before wiring.

适用边界：IEPE constant-current excitation is not a 4–20 mA process loop

Dynamic piezoelectric measurement normally has a low-frequency cutoff and is not a direct sustained-DC measurement; a different technology may support DC, subject to model evidence.

Verification: Define static versus dynamic duty, check principle and low-frequency limit and validate with an appropriate reference.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

Not automatically. A magnet, adhesive layer and surface condition change coupling stiffness and mounting resonance, affecting high-frequency amplitude.

Verification: Check mounting response over the target band and compare at a consistent prepared location.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

Integration amplifies low-frequency offset and noise effects; coupling, detrending and high-pass settings alter the result and require a justified lower band limit.

Verification: Retain acceleration, inspect baseline and lower-band settings and compare with a suitable velocity reference.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

Not necessarily. IEPE sensors and conditioning may require specified settling; connection transients affect data. Observe the documented settling period before using samples.

Verification: Check settling specifications and bias recovery; investigate supply, cable and range if the anomaly persists.

适用边界：IEPE constant-current excitation is not a 4–20 mA process loop

Align point, axis, mounting, band, quantity and RMS/peak definition; windows and overall algorithms also affect results. The same machine does not guarantee the same measurand.

Verification: Test synchronously with comparable locations and settings and retain waveforms and configuration.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output

No. Housing vibration and shaft-to-probe relative motion describe different relationships; support and rotor dynamics determine how they relate.

Verification: Identify the OEM-required quantity and location and do not copy thresholds between them.

适用边界：Different vibration quantities and RMS/peak definitions cannot share one threshold blindly

An overall metric is limited by its band and averaging. Local impacts or modulation may contribute little total energy; detection depends on sensing and analysis capability.

Verification: Review bandwidth, waveform and suitable analysis for the target fault rather than treating one overall value as complete health evidence.

适用边界：Mounting coupling and sensor bandwidth constrain high-frequency response

No. Machine class, support, quantity, band and operating state differ, as can applicable standards or OEM requirements; a generic number does not establish suitability.

Verification: Document the basis and baseline and obtain approval and verification of thresholds and delays.

适用边界：IEPE constant-current excitation is not a 4–20 mA process loop

No. Sensor/mounting bandwidth, anti-aliasing, duration and noise also matter. Sampling beyond useful bandwidth adds no genuine information, and frequency resolution depends on record length.

Verification: Choose rate and duration for the target band and low frequency and verify anti-aliasing and channel capability.

适用边界：Condition-monitoring output is not automatically machinery protection or safety output