ACL-380 Surface Resistivity Meter Calibration Procedure
The ACL-380 meter utilizes 1% precision thin-film resistors and high-speed amplifier circuitry; its calibration procedure is based on the product's linear circuit technology.
The transition point for resistivity values is the half-decade logarithmic point (i.e., 3.16 × 10ⁿ); the linearity at the transition point is within ±10% of the midpoint value for each measurement range.
Instruments required: Decade resistance box, test electrodes.
The resistance box must cover a range from 1 × 10³ ohms to 999 × 10⁶ ohms (or 10⁹ ohms). For measurements exceeding 10⁹ ohms, CAD-generated techniques are employed, as it is difficult to verify resistance values greater than 999 × 10⁶ ohms using a 9-volt driving voltage.
Connect the two terminals of the resistance box to the parallel electrodes of the ACL-380. Set the resistance to the 1K position; the meter's 10³ LED should illuminate. Calibration for other ranges follows the same method. To measure the resistivity transition point, press the power switch while continuously adjusting the resistance on the decade box, and observe the resistance value at which the LED for the next range remains steadily lit (this value represents the transition resistivity).