Understanding Piezoelectric Accelerometers

ডিভাইস

Portable balancer & Vibration analyzer Balanset-1A

€1,975.00 + ভ্যাট (যদি প্রযোজ্য হয়)

অংশ

Vibration sensor

€90.00 + ভ্যাট (যদি প্রযোজ্য হয়)

অংশ

Optical Sensor (Laser Tachometer)

€124.00 + ভ্যাট (যদি প্রযোজ্য হয়)

ডিভাইস

Balanset-4

€6,803.00 + ভ্যাট (যদি প্রযোজ্য হয়)

অংশ

Magnetic Stand Insize-60-kgf

€46.00 + ভ্যাট (যদি প্রযোজ্য হয়)

অংশ

Reflective tape

€10.00 + ভ্যাট (যদি প্রযোজ্য হয়)

ডিভাইস

Dynamic balancer “Balanset-1A” OEM

€1,735.00 + ভ্যাট (যদি প্রযোজ্য হয়)

A piezoelectric accelerometer is a vibration sensor that exploits the piezoelectric effect — the property by which certain crystals generate an electrical charge when mechanically stressed — to convert mechanical acceleration into an electrical signal proportional to vibration amplitude. When the sensor accelerates, an internal seismic mass compresses or shears a piezoelectric element, and the resulting charge or voltage is conditioned and output as a measurement signal. Thanks to a wide frequency range (roughly 0.5 Hz to 50+ kHz), high sensitivity, ruggedness, and a self-generating sensing element that needs no external power, the piezoelectric accelerometer is the most widely used vibration sensor in industry and the foundation of modern vibration analysis and condition monitoring.

1. The Piezoelectric Effect

Physical principle

• Certain crystals (quartz, tourmaline) and ceramics (PZT, barium titanate) are piezoelectric.
• Mechanical stress generates an electric charge on the crystal’s surfaces.
• The charge is proportional to the applied force.
• The effect is reversible — applying a voltage causes the element to deform.
• It is self-generating, so no power is needed to produce the charge itself.

Inside the accelerometer

The chain from motion to signal is short and direct:

1. Vibration accelerates the sensor base and housing.
2. The internal seismic mass experiences a force, F = m × a.
3. That force stresses the piezoelectric crystal.
4. The crystal generates a charge proportional to the force, and therefore to acceleration.
5. The charge is collected on electrodes and converted into a measurable signal.

Because the output tracks acceleration, the same signal can be electronically integrated to velocity for mid-frequency fault analysis, or used directly for high-frequency work.

2. Types by Internal Design

The way the crystal is loaded by the seismic mass defines the sensor’s character.

• Compression type: the most common design, with the crystal compressed between mass and base. Rugged, with a wide temperature range, it suits harsh environments — but it can be more sensitive to base strain and thermal transients.
• Shear type: the crystal is sheared by the mass’s motion. This geometry gives excellent base-strain isolation, better low-frequency response, and low sensitivity to temperature transients, which is why the shear accelerometer is the premium choice for demanding measurements.
• Flexural (bending) type: the crystal works in bending, enabling very high sensitivity, but it is less robust and less common in industrial use.

3. Types by Electronics

The second classification concerns whether the signal-conditioning electronics live inside the sensor or outside it.

• Charge mode: the output is a raw charge in picocoulombs, requiring an external charge amplifier. The high-impedance output is sensitive to cable movement and triboelectric noise, but with no internal electronics these sensors tolerate extreme temperatures (up to about 650 °C), making them indispensable for specialised high-heat applications.
• IEPE / ICP (voltage mode): built-in electronics convert the charge to a low-impedance voltage. The IEPE interface — also described as a voltage-mode accelerometer — is the industry standard, offering simple two-wire connectivity and excellent noise immunity. It serves well over 95 % of industrial applications.

4. Performance Specifications

Sensitivity

Sensitivity is the output per unit of acceleration — typically 10–100 mV/g for IEPE sensors, or 1–100 pC/g for charge mode. Higher sensitivity gives finer resolution but a lower maximum range, so the figure is chosen to match the expected vibration levels; the vibration sensor sensitivity calculator helps convert between an output voltage and the corresponding acceleration.

Frequency range

• কম ফ্রিকোয়েন্সি: a lower limit of about 0.5–5 Hz, set by the electronics.
• High frequency: an upper limit of 5–50 kHz, governed by the mounted resonance.
• Usable range: generally up to roughly one-third of the resonance frequency, where the response stays flat.
• Mounting effect: the mounting method strongly limits the achievable high-frequency response.

Amplitude range and dynamic range

• General purpose: ±50 g to ±500 g.
• High sensitivity: ±5 g to ±50 g.
• Shock sensors: ±500 g to ±10,000 g.

The signal must never exceed the sensor’s range, or it will clip and may damage the element; a wide dynamic range lets one sensor resolve both faint bearing tones and strong running-speed vibration in the same measurement.

5. Selection Criteria

Matching the sensor to the job is the heart of a good measurement setup.

• General machinery monitoring: a 100 mV/g IEPE accelerometer with a ±50 g range, a 1 Hz–10 kHz response, an industrial temperature rating (−40 to +120 °C), and a hermetic seal.
• Bearing defect detection: a higher frequency response (to 20+ kHz) to capture bearing fault frequencies, moderate sensitivity (10–50 mV/g), wide dynamic range, and stud mounting for the best high-frequency coupling — the right combination for catching incipient bearing defects.
• High-temperature applications: high-temperature IEPE (to about 175 °C) or charge mode (to about 650 °C), with special mounting and cabling, accepting some performance trade-off for the temperature capability.

6. Mounting and Installation

The mounting interface is part of the measurement system: it sets the mounted resonance and therefore the high-frequency limit. From best to worst:

• Stud mount: the best coupling, flat to 10+ kHz.
• Adhesive: good, flat to roughly 7–8 kHz.
• Magnetic: acceptable, flat to about 2–3 kHz.
• Probe / handheld: poor — limited to low frequencies and qualitative readings.

For reliable high-frequency data the surface must be clean and flat, the stud torqued correctly, any adhesive layer thin and even, the magnetic base fully seated, and the cable secured to prevent pulling. The mounting resonance calculator estimates where each method’s usable band ends; for permanently installed sensors the principles of correct sensor mounting are codified in ISO 5348.

In the field, these sensors are the front end of every portable analyser. A two-channel instrument such as the ব্যালানসেট-১এ uses IEPE accelerometers to capture the synchronised amplitude and phase needed for single- and two-plane ভারসাম্য and for routine diagnostics in the machine’s own bearings at operating speed. Together with the proximity probe and the velocity transducer, the piezoelectric accelerometer is one of the three principal vibration transducers — and by far the most versatile, which is why it remains the backbone of industrial vibration monitoring, diagnostics, and balancing worldwide.

---

← প্রধান সূচিতে ফিরুন