Question

What do IEPE and Isotron mean?

Answer

IEPE stands for Integrated Electronics PiezoElectric, usually in reference to a piezoelectric accelerometer with integral, built-in electronics. This is in contrast to a purely piezoelectric (PE) accelerometer that uses external electronics (typically a charge amplifier). The term Isotron is Endevco's trademark name for an IEPE accelerometer.

IEPE accelerometers give an output in voltage, with a sensitivity in mV/g units. In contrast, purely piezoelectric accelerometers give an output in charge, with a sensitivity in pC/g units. PE accelerometers need an external charge amplifier to convert the charge to voltage.

Endevco offers a wide variety of IEPE accelerometers. Contrary to popular belief, IEPE accelerometers can have a high dynamic range. For example, our model 7255A-01 has an amplitude range of +/-50,000 g. Because of their built-in electronics, IEPE accelerometers are often limited in their upper temperature limit. But this is not always the case. Our model 65HT-10 triaxial accelerometer is rated to 175°C (350°F), one of the highest temperature rated IEPE accelerometers on the market today. IEPE accelerometers can also have a very low frequency response and an incredibly low noise floor. Our model 87-1 is rated down to 0.015 Hz (+/-3dB) and has a typical broadband noise floor of less than 1500 ng rms.

Discussing the pros and cons of an IEPE accelerometer versus a PE accelerometer is beyond the scope of this topic (see technical paper TP320 on our web site), but it is worth mentioning that one of the major benefits of IEPE accelerometers is the simplicity of signal conditioning required. In fact, IEPE signal conditioning is so simple, anyone with basic electronics training could build their own rudimentary signal conditioner with commonly available electronic parts and a DC power supply.

For someone who wants a ready-made IEPE signal conditioner, our model 133 is available. The 133 provides three channels of IEPE signal conditioning in one package, and offers a lot of flexibility in accelerometer choices and output scaling for downstream data acquisition systems. Contact our applications engineers to further discuss your options with IEPE accelerometers and signal conditioning.