Minebea DSA-631 Instruction Manual Download Page 23

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3-2.

Operation Before Measuring

3-2-3. Stand alone Operation

(1)

Set the calibration value application switch (14) (+ * -) to the * (OFF) position.

(2)

Pressing power switch (19) (POWER) supplies power to the amplifier.

(3)

Set the measuring range to OFF (Measuring Range LED (11)) using measuring range selection

knob (8) (RANGE).

(4)

Setting the measuring range to OFF using measuring range selection knob (8) illuminates the green

LED in the middle of level meter (2). Activate for about 10 minutes.

(5)

For correct strain measurement, you must conduct initial balancing for the bridge circuit.

Tune to your target measuring range using measuring range selection knob (8) and adjust the
output to zero while no load is being applied.

(6)

Bridge check, cable length compensation, and automatic balancing
Turn measuring range selection knob (8) clockwise up to your target measuring range, and then

narrow the measuring range (i.e. increasing sensitivity). In this case, the indication of measuring
range LED (11) changes from OFF to other values, in that the value changes toward 200. Pressing

the BAL knob (4) performs the bridge check, cable length compensation (indication of the rate of

damping), and auto balancing in this order. For more information, see Indication upon the
paragraph 9. Execution of BAL. (These functions are available when the dip switches for the bridge

check and cable length compensation are set to ON.)
When there is neither cable disconnection nor a short, and indication of Good is indicated on the
digital monitor (3), and then the cable length compensation (indication of the rate of damping) and

auto balancing are performed. If there is a cable disconnection or short, the examination results are

indicated on the digital monitor (3) respectedly. The contents to be indicated are listed on the

paragraph 15

16. Following the indicated result (paragraph 16), repair the cable or bridge. After

the repair, press BAL again for at least five seconds to check for failures.
The cable length compensation automatically calcurates the voltage drop occurring in the cable
connecting between the DSA-631 amplifier and measurement point (bridge), saving this calculation

data into the internal memory. The power supply to the bridge is provided after this adjustment. As

a result, high accuracy strain measurement is available without considering the conductor
resistance generated by the cable.
After the cable length compensation is made, the initial balance is made, and then the green LED in

the middle comes on. For further fine-tuning, turn the BAL knob (4) clockwise or anti-clockwise. The

adjustment range is an output of

1 V.

* The cable length compensation data is stroed in the internal memory until the BAL switch is

pressed, even if the power switch (19) is turned on or off. The wire length function is set to off or
non-adjustment by the dip switch on the bottom face of the DSA-631.
* For more information on bridge check function and cable length compensation, see the paragraph

18.

(7)

In response to the magnitude of the strains anticipated, apply a calibration value using the

calibration setting knob (12) first, and then start measuring.
The measuring range can be checked after applying a calibration value using the calibration value

application switch (14). The measuring ranges for DSA-631 amplifiers are described in Measuring
Ranges for DSA-631 on page 14.