IEPE stands for Integrated Electronics Piezo Electric and defines a class of accelerometer that has built-in electronics. Specifically, it defines a class of accelerometer that has low impedance output electronics that work on a two-wire, constant current supply with a voltage output on a DC voltage bias. IEPE, two-wire accelerometers are easy to install, have a wide frequency response, can run over long cable lengths and are relatively cheap to purchase. The IEPE technology has generally replaced most three-wire accelerometers and is broadly used for most applications except for specialist applications, such as zero Hz accelerometers, high temperature applications or 4-20 mA accelerometers used in the process industries.