A practical framework for selecting accelerometers across industrial vibration, structural testing, and crash applications. Compare charge mode, IEPE, and MEMS technologies on the parameters that actually drive failure: frequency response, sensitivity, mounting, and survival under shock.
What’s Covered
The three accelerometer technologies in one minute
An accelerometer turns mechanical motion into a measurable electrical signal. Three technologies dominate industrial use, and each has a distinct best-fit operating envelope.
Charge mode (piezoelectric, external charge amplifier)
The classic piezoelectric design. The crystal generates a charge proportional to acceleration; an external charge amplifier converts that charge to a voltage. Charge mode shines at extreme temperatures (well beyond IEPE limits) and where users want full control over signal conditioning. Cabling is critical, the cable between sensor and amplifier acts as part of the circuit, so cable quality and length matter.
IEPE / CCLD (integrated electronics)
IEPE, Integrated Electronics Piezoelectric, sometimes called CCLD (Constant Current Line Drive) in HBK terminology, embeds the charge amplifier inside the sensor. The sensor outputs a low-impedance voltage signal, powered by a 2–20 mA constant-current source from the conditioner. IEPE is the workhorse of industrial vibration measurement up to roughly 175 °C. It tolerates long cable runs and is straightforward to integrate with standard DAQ.
MEMS (micro-electromechanical)
MEMS accelerometers etch a silicon proof mass and capacitive readout into a chip. They measure DC and very low frequency events that piezoelectric devices cannot, are inexpensive at moderate accuracy, and can be packaged extremely small. They dominate automotive crash, condition monitoring, and tilt-aware applications. Premium MEMS such as the Jewell Instruments AKA, AMA, and ASB series approach the noise floor of laboratory-grade piezoelectric units in their target band.
How to choose: a six-parameter selection framework
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Frequency range of interest
Identify the highest frequency you must resolve. Charge mode and IEPE cover from a few Hz to tens of kHz; MEMS resolves DC to typically a few kHz. Match the sensor’s flat band, with margin, to your highest frequency of interest.
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Amplitude range and dynamic range
Check the maximum survival shock as well as the linear measurement range. Crash testing demands sensors rated for thousands of g without saturation or damage; balance assessment may require resolution below 0.001 g.
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Operating temperature
IEPE typically tops out at 125–175 °C. Charge mode handles 250–500 °C with appropriate cable. MEMS varies widely, confirm against datasheet, not generic technology averages.
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Mounting and mass loading
The sensor’s effective frequency band is set by how it is mounted, not just its specification. Stud-mount achieves the catalog frequency; magnetic and adhesive mounts cut it sharply. For lightweight DUTs, the sensor’s mass relative to the structure determines how much you contaminate the measurement.
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Output type and conditioning
Charge, IEPE, voltage, or digital. The output type determines compatible signal conditioning and whether you can plug directly into your existing DAQ. Mixing these without matched conditioning produces unusable data.
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Environmental protection
Hermetic sealing for humidity, ground isolation for industrial EMI environments, ATEX or similar approvals for hazardous areas, and case material for chemical exposure.
Technology comparison table
| Parameter | Charge mode | IEPE / CCLD | MEMS |
|---|---|---|---|
| Bandwidth (typical) | 0.5 Hz – 30 kHz+ | 0.5 Hz – 25 kHz | DC – several kHz |
| DC response | No | No | Yes |
| Noise floor | Low to very low | Low | Moderate (premium MEMS approaches piezoelectric) |
| Max temperature | 250–500 °C with rated cable | 125–175 °C | Varies; commonly 85–125 °C |
| Cable sensitivity | High (cable is part of circuit) | Low (low-impedance output) | Low |
| Powering | External charge amplifier | 2–20 mA constant current source | External DC supply |
| Best fit | Extreme temperature, reference-grade | General industrial vibration, NVH | Crash, tilt, low-frequency, condition monitoring |
Specify the mounting at the same time as the sensor. A 25 kHz IEPE accelerometer mounted with a magnet on a painted surface delivers maybe 2 kHz of usable bandwidth. The mounting choice is part of the specification, not an installation detail.
Mounting and the frequency you actually get
Mounting interfaces directly determine usable bandwidth. The same sensor on three different mounts can deliver three different frequency responses.
- Stud mount, full catalog bandwidth; preferred for permanent installations and reference measurements
- Adhesive mount with stiff cement, close to stud-mount when surface is clean and adhesive is applied per spec
- Magnetic mount, convenient for routes and walk-around measurements; bandwidth typically 2–5 kHz
- Hand probe, operator-dependent and rarely useful above 1 kHz
- Wax, fast for short-duration tests; verify temperature stability before relying on it
Cable routing is part of the mounting plan: avoid sharp bends near the connector, secure cables to prevent triboelectric noise from movement, and respect minimum bend radius.
Applications: industrial vibration vs. crash testing
Industrial vibration and condition monitoring
Most rotating machinery monitoring uses IEPE accelerometers (such as the HBK 4507/4508 family) mounted permanently to the bearing housing, feeding a continuous monitoring or route-based system. Sensitivity targets in the 100 mV/g range cover most balance, alignment, and bearing diagnostics. For predictive maintenance program design, see the cluster guide on industrial vibration monitoring.
Crash and impact testing
Crash sensors must survive thousands of g without damage and recover quickly without baseline shift. Specialized crash-rated MEMS units and dedicated piezoelectric devices designed for crash environments are typical. Triaxial configurations are standard, and TEDS (see TEDS technology guide) accelerates rig setup before each test event.
Modal analysis and structural testing
Modal work uses a combination of clean force input from modal exciters and high-quality reference accelerometers to identify resonant frequencies and mode shapes. Cross-channel synchronization (provided by HBK LAN-XI / Fusion-LN front ends) is essential for clean transfer functions.
Browse the full Durham Instruments accelerometer catalog for HBK piezoelectric series, Jewell Instruments MEMS, and supporting accessories.
FAQ
Should I use IEPE or charge mode for high-temperature applications?
Above the IEPE limit of roughly 175 °C, charge mode is generally the right answer. The integrated electronics in an IEPE sensor cannot survive higher temperatures. Charge mode keeps the electronics elsewhere, and high-temperature charge accelerometers paired with rated cabling can operate well above 250 °C.
Can MEMS accelerometers replace piezoelectric for vibration monitoring?
For many condition monitoring applications, premium MEMS performs comparably to piezoelectric in its target band, and adds DC response and low-frequency capability that piezoelectric does not have. For high-frequency content above a few kHz, piezoelectric remains the right choice.
What sensitivity should I order, 10, 100, or 500 mV/g?
Match sensitivity to expected amplitude. 100 mV/g is the most common default for industrial vibration measurement. Use 500 mV/g for low-amplitude work where noise floor matters; use 10 mV/g or lower for shock and crash where you need range without clipping.
How does mounting affect the upper frequency limit?
The mount adds a mechanical resonance below or near the sensor’s own natural frequency. Stud mount preserves the catalog spec; adhesive is close behind; magnetic typically halves the upper limit; wax and probe further reduce it. Always specify mounting alongside the sensor.
Does Durham Instruments calibrate accelerometers?
Yes. Durham Instruments offers traceable calibration of accelerometers through OEM laboratories and qualified partners, with documented uncertainty and traceability suitable for ISO 9001 and audit-grade requirements.
Need help shortlisting accelerometers?
Send the operating envelope, frequency band, and DAQ in use, our team will return a fit-for-purpose sensor selection with conditioning and calibration support.