OMEGA BCM-2-120R Offers

Strain gage instrumentation is readily available with built-in bridge completion resistors and “dummy” gages to accept quarter- and half-bridge strain gage input circuits. However, if the instrumentation at hand is not provided with these components, or if the measurement application does not permit their use, external bridge completion must be provided, and the BCM-2-350R Series Bridge Completion Module can be an excellent choice in these applications.

The OMEGA® Bridge Completion Module provides a convenient means of completing the Wheatstone Bridge circuit used for strain gauge measurements. The module can be used for quarter bridge measurements with 120 or 350 ohm gauges or for half bridges with gauges of any resistance.

The BCM-2-350R Series Bridge Completion Module employs metal-foil resistance elements, bonded to a dense ceramic substrate. The resistance elements are specially processed to “match” the thermal expansion coefficient of the ceramic, resulting in a very low resistance temperature coefficient.

Quarter bridges with two or three wire hookup can be accommodated. In addition, a bridge balance adjustment potentiometer is provided to zero the bridge output.

Each module is covered with a special environmental protection system to ensure long-term stability. A rugged aluminum overlay, embossed with a wiring diagram for easy terminal identification, affords additional protection, and in many applications no supplementary environmental protection is required.

Each module is provided with foam tape for easy attachment to the test-part surface or at the instrumentation site, and tinned, heavy copper terminals facilitate attachment of up to 0.025 in diameter [0.64 mm, 22-gage] leadwires.

Completing the bridge circuit at the strain gage site provides for a symmetrical, balanced leadwire system between the strain gage circuit and the instrumentation. This can reduce effects of noise pickup in the leadwire system in some environments.

Where switch contacts, slip rings, or other mechanical connections are employed between the strain gages and measuring instrumentation, or when leadwires will be periodically disconnected from the measuring instrument, accuracy can be improved by completing the bridge at the measurement site. Bridge completion modules can be designed to meet special circuit requirements.

Features

• Completes the wheatstone bridge circuit for strain gauge measurements
• Used for quarter bridge measurements with 120 or 350 ohm gauges or half bridges with gauges of any resistance
• Accommodates quarter bridges with two or three wire hookup
• Bridge balance adjustment potentiometer provided to zero the bridge output
• Constructed using precision resistors with 5 ppm/°C temperature coefficient for maximum temperature stability
• Completely encapsulated for use in rugged environments

Applications

• Completing quarter-bridge strain gage circuits where instrumentation lacks built-in bridge completion
• Strain gauge measurements
• Building half-bridge strain gage measurement circuits with external bridge completion
• Quarter bridge strain measurement
• Providing balanced leadwire systems to reduce noise pickup in strain measurement
• Half bridge strain measurement
• Completing the bridge at the gage site where slip rings or switch contacts are used
• Wheatstone bridge completion
• Bridge output zeroing