Understanding IEPE Accelerometers

Devices

Portable balancer & Vibration analyzer Balanset-1A

Parts

Optical Sensor (Laser Tachometer)

Complete vibration diagnostics and balancing kit from Vibromera, including four vibration sensors with cables, a signal interface module, laser tachometer with magnetic stand, digital scale, USB cable, and a carrying case. The system is designed for field rotor balancing and condition monitoring on industrial equipment.

Devices

Dynamic balancer “Balanset-1A” OEM

Definition: What is an IEPE Accelerometer?

IEPE accelerometer (Integrated Electronics Piezo-Electric, also called ICP®, voltage mode, or constant current accelerometer) is a piezoelectric accelerometer with built-in signal conditioning electronics powered by a constant current (typically 2-20 mA) supplied through the same two-wire cable that carries the output signal. The internal electronics convert the high-impedance charge from the piezoelectric crystal into a low-impedance voltage output, eliminating the need for external charge amplifiers and enabling use of simple, low-cost coaxial cables over long distances.

IEPE accelerometers have become the industry standard for industrial vibration monitoring, used in over 90% of applications due to their simplicity, reliability, and cost-effectiveness. They are the sensor of choice for condition monitoring, balancing, and troubleshooting in most industrial environments.

Operating Principle

Internal Construction

Piezoelectric Element: Generates charge proportional to acceleration
Built-In Amplifier: FET or IC amplifier inside sensor housing
Impedance Conversion: Converts high-impedance charge (pC) to low-impedance voltage (mV)
Single Cable: Two-conductor cable for both power and signal

Power and Signal Path

Instrument provides constant current (typically 4 mA)
Current powers internal electronics
Vibration modulates voltage on same cable
AC-coupled output (vibration signal) rides on DC bias voltage
Instrument separates DC power from AC signal

Key Advantages

Simplicity

No external amplifier required
Simple two-wire connection
Standard coaxial cable (low cost)
Easy installation and setup

Long Cable Capability

Low-impedance output drives long cables
Cable lengths to 300m (1000 ft) practical
Minimal signal degradation
No special cable requirements

Noise Immunity

Low-impedance less susceptible to electrical interference
Better EMI/RFI rejection than charge mode
Suitable for electrically noisy environments

Cost-Effectiveness

Eliminates expensive charge amplifiers
Reduces system cost
Lower installation cost
Industry-standard sensors widely available

Specifications and Performance

Typical Specifications

Sensitivity: 10-100 mV/g common (100 mV/g standard)
Frequency Range: 0.5 Hz – 10 kHz (low-frequency cutoff from AC coupling)
Measurement Range: ±50g to ±500g typical
Temperature Range: -50°C to +120°C standard; high-temp versions to +175°C
Power Required: 18-30 VDC, 2-20 mA constant current

Performance Characteristics

Excellent linearity (typically < 1% error)
Low noise floor
Good frequency response flatness
Stable calibration over time

Limitations

Low-Frequency Response

AC-coupled output (capacitor blocks DC)
Low-frequency cutoff typically 0.5-2 Hz (-3 dB point)
Cannot measure true DC or very slow changes
Adequate for most machinery (>300 RPM) but limitation for very low speeds

Temperature Limitations

Standard IEPE limited to ~120°C
High-temp versions to 175°C but more expensive
Above limits, electronics fail
Alternative: charge-mode accelerometers for very high temp (>200°C)

Ground Loop Sensitivity

Common mode rejection moderate
Can be affected by ground potential differences
Proper grounding and isolation important
Usually not problem with proper installation

Applications

Condition Monitoring

Route-based data collection with data collectors
Permanent online monitoring systems
Temporary monitoring for troubleshooting
Most common industrial vibration sensor

Balancing

Field balancing measurements
Shop balancing machines
Amplitude and phase measurement

Acceptance Testing

New equipment commissioning
Post-repair verification
Contractual vibration verification

IEPE vs. Other Accelerometer Types

IEPE vs. Charge Mode

IEPE: Built-in electronics, simple cable, lower cost, limited temperature
Charge Mode: No electronics, requires charge amplifier, extreme temperatures possible
Use IEPE: 95% of industrial applications
Use Charge: Extreme temperatures (>175°C), nuclear environments, special applications

IEPE vs. MEMS

IEPE: Piezoelectric crystal, higher performance, industry standard
MEMS: Micro-machined silicon, lower cost, integrated systems
IEPE Advantages: Better sensitivity, wider bandwidth, proven reliability
MEMS Advantages: Lower cost, smaller size, DC response

Installation Best Practices

Mounting Methods

Stud Mount: Best performance, highest frequency (to 10+ kHz)
Adhesive: Good performance, semi-permanent (to 7-8 kHz)
Magnetic: Convenient, acceptable for routine monitoring (to 2-3 kHz)
Handheld: Quick screening only, limited accuracy and frequency range

Cable Considerations

Use quality coaxial cable
Avoid cable damage (crushing, sharp bends)
Secure cable to prevent vibration
Keep cables away from high-voltage sources
Verify continuity and insulation

Power Supply Verification

Verify instrument provides proper constant current (2-20 mA typical)
Check bias voltage (typically 8-12 VDC)
Ensure adequate supply voltage (18-30 VDC)
Test with known-good sensor to verify instrument

IEPE accelerometers represent the optimal balance of performance, simplicity, and cost for industrial vibration monitoring. Their integrated electronics, simple connectivity, and robust performance have made them the overwhelming choice for condition monitoring, balancing, and troubleshooting applications across all industries, replacing older charge-mode and voltage-output technologies in most standard applications.

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What is an IEPE Accelerometer? Integrated Electronics Sensor

Published by admin on October 31, 2025 October 31, 2025