General Purpose vs. Low Frequency Accelerometers
OVERVIEW:
- CTC’s AC102 Sensors provide a 100 mV/g output over the range of 0.5-15,000 Hz (± 3dB).
- The AC102 is compatible with thousands of applications and is a multipurpose accelerometer.
- CTC’s AC133 and AC153 Series Sensors provide a 500 mV/g output over the range of 0.1 to
10,000 Hz (± 3dB). - The AC133 and AC153 are specifically designed for low-speed rotors, main bearings, and gearbox
inputs, but also can be used for high-frequency detection (up to 600,000 CPM).
SENSITIVITY:
Most general-purpose accelerometers have a nominal sensitivity of 100 mV/g. Low-frequency sensors however have a greater output sensitivity of 500 mV/g and some that are larger at 1000 mV/g. The larger mV/g output gives the sensor sufficient voltage signals, which will improve its ability to read low amplitude vibration signals down to 0.1 Hz at 3dB. Most low-frequency measurements are associated with low levels of vibration.
When the main bearing has a rotational frequency that is less than 30 CPM (0.5 Hz) it often requires the use of a low-frequency accelerometer. The AC102 has a frequency response of 30 to 900,000 CPM (0.5-15k Hz) and does not have the capability of providing accurate readings on slow-moving applications. The low-frequency accelerometers have a frequency response of 6 to 600,000 CPM (0.1-10k Hz), this provides the ability to monitor low frequency and low amplitude vibration levels. These accelerometers are specifically designed to enable pure low-frequency measurements and use high-frequency detection and analysis techniques all in one hermetically sealed sensor.
TYPICAL FREQUENCY RESPONSES:
Overall, both sensors offer a great frequency response and can be used for many applications. The AC102 is a perfect sensor for almost all applications, but when the frequency is below 30 CPM, the AC133 and AC153 could be the best option.
