Vibration velocity sensors from Brüel & Kjær Vibro operate according to the electro-dynamic principle. In a coil which moves back and forth in the field of a permanent magnet a voltage proportional to the vibration velocity is induced. The coil is suspended in a friction-free manner by two helical membrane springs and forms a spring-mass system. When the casing of the sensor is attached or applied to a vibrating object, e.g. a machine casing, the coil remains stationary in space above the natural frequency of the spring-mass system. In this way the absolute vibrations occurring at the surface of the machine, e.g. the bearing housing, are acquired.
According to the construction of the sensor the natural frequency is 8 Hz or 15 Hz. With the employment of an electronic frequency response linearization circuit, it is possible to measure absolute vibrations well below the natural frequency of the sensor with the required accuracy. Vibration measuring instruments from Brüel & Kjær Vibro are equipped with frequency linearization circuits of this type. In the case of vibration monitoring systems, this option can be built in as an option.
Vibration velocity sensor are extremely rugged in construction and are absolutely oil-, water- and vaccum-tight. The rust-free stainless-steel casings permit long-term use in chemically aggressive atmospheres and extreme environments and climates.
Special features
- A sensor for measurement of absolute vibrations in the frequency range from 1 to 2000 Hz
- Rugged construction with small dimensions and low weight
- Can be supplied with electronic frequency-response linearization for measurement of vibrations down to 1 Hz
- Output signal proportional to vibration velocity
- Operating temperature range from -40°C to +80°C or +200 °C
- Active sensor with high sensitivity and low internal resistance which requires no power to operate
- Simple mounting in the measurement direction by means of an M8 or M10 central threaded hole
- Corrosion-resistant stainless-steel casing
- Hermetically encapsulated, protection class IP 66 according to DIN 40 050
- Explosion-proof version and underwater version are also available
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