Accelerometer input module provides excitation

Edited by the Engineeringtalk editorial team Jun 6, 2006

The SCM5B48 isolated and field-configurable accelerometer input module provides excitation to piezoelectric sensors with built-in microelectronic amplifiers.

New from Dataforth Corporation, the SCM5B48 isolated and field-configurable accelerometer input module provides excitation to piezoelectric sensors with built-in microelectronic amplifiers, commonly known as ICP or IEPE sensors.

The module provides a constant current excitation to the sensor, then isolates, filters, and amplifies the sensor output, yielding a high-level analogue voltage output.

The excitation current, signal gain, and filter high-pass and low-pass cut off frequencies are field-configurable through a set of slide switches.

Six poles of signal filtering in the SCM5B48 module result in greater than 100dB of normal-mode rejection for signal frequencies above the cut off frequency.

One pole of filtering is on the field side of the isolation barrier for anti-aliasing purposes and the remaining five-pole programmable filter is located on the system side.

Highpass filtering is achieved through a second-order passive filter, located on the field side.

As excitation current needs may vary from application to application, especially when long sensor lines are required, the SCM5B48 offers the option of setting the constant current source for sensor excitation to common values of 4 or 9mA with a compliance voltage of 24V DC.

To ensure protection of expensive data acquisition equipment, the SCM5B48 module signal inputs and sensor excitation outputs are protected against accidental connection of voltages up to 240V RMS.

The high performance isolation barrier breaks ground loops, allows operation at high common-mode input voltages and rejects large common-mode spikes, all of which contribute to preserving signal integrity while maintaining a high level of accuracy and low output noise.

Developed in response to customer requests for a compact, universal, low cost isolated signal conditioner interfacing to industry standard accelerometers, the SCM5B48 accelerometer input module ensures fully functional instrument class performance in a package that is smaller than competing module products.

Since its conception, the SCM5B48 has been designed for simple field reconfiguration any time the application requirements change.

Any combination of selectable parameters is allowed.

This flexibility enables a single module to be used in many scenarios while offering the traditional isolation and protection features of Dataforth's SCM5B family.

Measuring only 58 x 57 x 15mm, the SCM5B signal conditioner is smaller than similar products, making it ideal for applications where space is at a premium.

Housed in a solid, potted thermoplastic plug-in-the-panel package with flammability rating of UL94V0, the SCM5B family of isolated signal conditioners is specifically designed to protect user equipment, while reducing electrical noise and enabling convenient system expansion and repair.

All SCM5B modules offer dimensional stability over temperature, chemical resistance, and electrical stability over time and temperature.

Operation and storage temperature for the SCM5B modules is -40 to +85C; relative humidity range is zero to 95% noncondensing.

All models meet the requirements of EN61000-6-4 (radiated/conducted emissions) and EN61000-6-2 (ESD/RF/EFT immunity).

For operation in hazardous environments, North American Class I, Division 2, and European Group II, Category 3, approvals are pending.

Design-in accessories for the SCM5B line include a selection of single-, dual-, four-, eight- and 16-channel backpanels that provide field screw-terminal and screw terminal or ribbon cable output to a data acquisition system.

Custom signal conditioning models will be available to meet unique signal conditioning needs, and the SCM5B48 will soon be available in a DIN mount configuration.