The abbreviation IEPE stands for Integrated Electronics Piezo-Electric. It characterises a

technical standard A technical standard is an established norm or requirement for a repeatable technical task which is applied to a common and repeated use of rules, conditions, guidelines or characteristics for products or related processes and production methods, ...

for piezoelectric sensors which contain built-in impedance conversion electronics. IEPE sensors are used to measure

acceleration In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by t ...

, force or

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

. Measurement

microphones A microphone, colloquially called a mic or mike (), is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public ...

also apply the IEPE standard. Other proprietary names for the same principle are ICP, CCLD, IsoTron or DeltaTron. The electronics of the IEPE sensor (typically implemented as

FET The field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current in a semiconductor. FETs (JFETs or MOSFETs) are devices with three terminals: ''source'', ''gate'', and ''drain''. FETs contr ...

circuit) converts the high impedance signal of the piezoelectric material into a

voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...

signal with a low impedance of typically 100 Ω. A low impedance signal is advantageous because it can be transmitted across long cable lengths without a loss of signal quality. In addition, special low noise cables, which are otherwise required for use with piezoelectric sensors, are no longer necessary. The sensor circuit is supplied with

constant current A constant current (steady current, time-independent current, stationary current) is a type of direct current (DC) that does not change its intensity with time. Sources If the load is constant, a steady current can be obtained via a constant vo ...

. A distinguishing feature of the IEPE principle is that the power supply and the sensor signal are transmitted via one shielded wire. Most IEPE sensors work at a constant current between 2 and 20 mA. A common value is 4 mA. The higher the constant current the longer the possible cable length. Cables of several hundred meters length can be used without a loss of signal quality. Supplying the IEPE sensor with constant current, results in a positive bias voltage, typically between 8 and 12 volts, at the output. The actual measuring signal of the sensor is added to this bias voltage. The supply or compliance voltage of the constant current source should be 24 to 30 V which is about two times the bias voltage. This ensures maximum amplitudes in positive and negative direction. A typical IEPE sensor supply with 4 mA constant current and 25 V compliance voltage has a

power Power most often refers to: * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power * Power (social and political), the ability to influence people or events ** Abusive power Power may a ...

consumption of 100 mW. This can be a drawback in battery powered systems. For such applications low-power IEPE sensors exist which can be operated at only 0.1 mA constant current from a 12 V supply. This may save up to 90 % power. Zibbix ICP Injection Control Pressure Sensor For 94-03 7.3L Powerstroke
/ref> IEPE bias voltage

Many measuring instruments designed for piezoelectric sensors or measurement microphones have an IEPE constant current source integrated at the input. In measuring instruments with IEPE input the bias voltage is often used for sensor detection. If the signal lies close to the constant current supply voltage, there is no sensor present or the cable path has been interrupted. A signal close to the saturation voltage, indicates a short circuit in the sensor or cable. In between these two limits a functional sensor has been detected. The bias voltage is cut off by a coupling capacitor at the instrument input and only the AC signal is processed further. Iepe principle

Piezoelectric sensors which do not possess IEPE electronics, meaning with charge output, remain reserved for applications where lowest frequencies, high operating temperatures, an extremely large

dynamic range Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of Signal (electrical engineering), signals, like sound and light. It is measured ...

, very energy saving operation or extremely small design is required.

References

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External links

IEPE principle, Metra
Sensors Accelerometers