Precision ICP® Accelerometers

IMI Sensors offers a wide range of ICP® accelerometers with an AC voltage output. These accelerometers are ideal for route based and permanently-mounted predictive maintenance applications. The AC voltage output can interface with third-party data collectors or other online monitoring systems for analysis.

ICP® accelerometers operate on a simple, two-wire system consists of an 18-30 VDC power source, current-regulating diode, voltmeter and decoupling capacitor.

18-30 VDC Power Source: Supply voltage can be provided by line or battery power. Most line-powered signal conditioners supply 24 VDC power as they are connected to an external 24VDC power source. The power provided by a battery-powered signal conditioner can vary depending on the number and voltage of the batteries.

Current-Regulating Diode: ICP® accelerometers require a fixed constant current between 2 and 20 mA so the power must pass through a current-regulating diode. There is an approximate 1V drop across the diode.

Voltmeter: The power is transmitted to the ICP® accelerometer via two-conductor cable with one conductor acting as the ground and the other conductor transmitting both the power to the sensor and the output signal from the sensor. The portion of the voltage used to power the accelerometer's amplifier is called the bias voltage and is usually in the range of 8-12 VDC. The voltmeter monitors this bias voltage and is useful for checking sensor operation. The output signal is an AC dynamic signal that rides on top of the bias voltage.

Decoupling Capacitor: When the output signal is received at the signal conditioner, the DC bias voltage must be decoupled from the AC signal voltage in order to record accurate data. The 10-30 μF capacitor shifts the signal level to essentially eliminate the sensor bias voltage, providing a drift-free AC mode operation.