3270 Daytronic Physical Measurement Equipment

Additional Features:

• Input Type: Conventional 4-arm strain gage bridge, nominal 90 to 2000 Ohm
• Input Range (full-scale): Nominal sensitivity 1 to 8 mV/V, full scale
• Ten-turn coarse and fine front-panel controls will balance 1.5 mV/V initial unbalance and allow span adjustment over the stated full-scale sensitivity
• Excitation Supplied: Regulated 5 or 10 V-DC, user selectable
• Analog Outputs: Three outputs, each ±5 V full-scale with 50% over range, 5 mA max.; low-pass corner frequencies of 2 Hz, 200 Hz, and 2 kHz, respectively
• Common-Mode Rejection: Greater than 80 dB Input Impedance: Greater than 100 M½
• Analog Filtering: Active low-pass filters provide -60 dB per decade above cutoff frequency (“f”); full-scale slew time is 1.4/f sec
• Output Ripple and Noise: 0.15% of full scale (rms) max. for 200-Hz and 2-kHz outputs; 0.02% of full scale (rms) max. for 2-Hz output
• Accuracy (typical, following Calibration): 0.05% of full scale Display Resolution (Models 3270 and 3370): 0.02% of full scale***Includes the combined effects of nonlinearity, random noise, line-voltage variation between 105 and 130 volts, ambient temperature variation of ±20° F about starting value, and six months drift of zero and span. Errors attributable to the transducer are not included
• Case: Each unit is housed in a single piece of heavy gage aluminum (1.7” H x 4.41” W x 7.0” D); a simple reassembly procedure allows mounting in the user’s precut panel; the Model 3004 Rackmount Adaptor permits secure mounting of up to four units in a standard 19-inch rack
• Operating Temperature Range: 0° F to +130° F (-18°C to +55° C); assumes dry, noncondensing ambient atmosphere
• Power Voltage: 105-135 V-AC
• Frequency: 50-400 Hz
• Consumption: 5 W max. (for Form 1 instruments), 8 W max. (for Form 2 instruments), or 9 W max. (for Form 3 instruments) Display (Form 2 and Form 3 instruments only)
• Display: Orange LED’s, six digits with polarity sign, 0.4” (1.0 cm) height; Most Significant Digit of display is either unlit or reads “1,” and in either case contains polarity sign; Least Significant Digit is a dummy zero which may be lit or unlit, as desired
• Scaling: Selectable at rear panel; full-scale values of ±5000 counted by “1’s,” ±10000 counted by “2’s,” or ±20000 counted by “5’s,” with selectable decimal point locations (along with dummy zero) to give decade multiplier factors of 10, 1.0, 0.1, 0.01, 0.001, or 0.0001
• Display Sampling Update Rate: 3 samples per second
• Remote sensing and regulation of bridge excitation—eliminates errors from temperature effects on cable resistance
• Seven-wire calibration circuitry—applies the internal shunt calibration resistor at the transducer terminals, thereby eliminating significant calibration transfer error in long-cable installations
• True differential input, with better than 80 dB of common-mode rejection—eliminates errors from common-mode pickup and possible “ground-loop” coupling
• Input impedance in excess of 100 megaohms preserves the validity of factory calibration, prevents conversion of common mode to normal-mode signals, and eliminates remaining errors attributable to cable resistance. Allowable cable length has virtually no practical limits
• Elimination of both short-term and long-term drift through an advanced solid-state chopper stabilization technique, while preserving the full frequency passband, free of chopper noise; the rated accuracy is obtained without “warm-up” period or periodic “tweaking” of controls
• Active low-pass filtering smooths unwanted dynamic signal components arising from vibration, power impulses, etc., that might prevent stable digital conversion or control action

The Models 3170, 3270, and 3370 DC Strain Gage Conditioners are highly accurate DC instruments for use with load cells, pressure sensors, and other strain gage transducers employing a 4-arm bridge.

The Model 3170 Strain Gage Conditioner is the basic Form 1 instrument. The Model 3270 Strain Gage Conditioner/ Indicator is the Form 2 instrument, providing vivid front panel digital indication of measured values, scalable in desired engineering units. The Model 3370 Strain Gage Conditioner/Indicator/Controller is the Form 3 instrument, and includes HI/LO limit detection with control output. Advanced circuit design overcomes many of the errors traditionally afflicting the strain gage measurement process, resulting in three high level, drift-free, noise-free analog outputs (see Specifications). Nearly all mechanical measurement and control requirements are covered by these three simultaneously available outputs.