AS-668 B&K Vibro Compact, Low Frequency Accelerometer

Supported Applications

The AS-668 Series is a compact, low-frequency accelerometer by Brüel & Kjær Vibro (Omega), designed for monitoring rotating machinery. The series supports vibration measurement on turbines, fans, pumps, and generators.

Operating Conditions & Performance

Based on the piezoelectric principle (compression type), the sensor converts mechanical vibration into an electrical signal with a nominal sensitivity of 100 mV/g ±10 % at 80 Hz. The frequency response is specified as 0.5 Hz to 13 kHz (±3 dB) and 1.5 Hz to 10 kHz (±10 %). Amplitude linearity is less than 1 %, with a cross sensitivity of typically 5 %. The measurement range covers up to 60 g Peak, while the overload capacity supports constant sinusoidal vibration up to 500 g and shock loads up to 5.000 g.

The device operates within an ambient temperature range of -55 °C .. +125 °C. Storage in original packaging is rated for -20 °C .. +70 °C. The sensor features a hermetically sealed stainless steel housing (material 1.4404) with a degree of protection acc. EN 60529 of IP66 / IP67.

Electrical Specifications

• Power Supply: Constant current supply, secure against reverse polarity; 2 mA .. 10 mA.
• Bias Voltage: Typically 12.9 VDC (across entire temperature range: 12.4 VDC .. 13.4 VDC).
• Output Resistance: 100 Ω.
• Maximum Output Voltage: 27 V.

Configuration Options

The AS-668 Series is configured with a robust stainless steel housing and an integrated M12 male, 4-pole plug for electrical connection. The sensor includes the following configurable or standard features:

• Mounting: ISO 4762 M6x30 or ¼-28UNFx30 threaded mounting with a recommended torque of 3,5 Nm.
• Cable Options: Available accessories include AC-1403 (double-wired connection cable with straight plug) and AC-1404 (double-wired connection cable with angled plug).
• Housing Isolation: Housing is isolated against sensor electronics.

Key Product Differences

The AS-668 model represents a general-purpose accelerometer within the series. The primary technical distinction lies in its constant current supply architecture and specific M12 male connector configuration, differentiating it from charge-output or voltage-output sensors requiring external conditioning.