Features and Benefits

The model 8000B is a highly versatile, accurate, self-balancing instrument that meets laboratory requirements for scaling between 10 Volt references or any voltage between 1 mV to 10 Volts. Automatic self-calibration ensures ratios to nine significant digits with linearity deviations of less than 0.02 ppm. The model 8000B has a 20-channel “built-in” scanner addressed individually via the Windows operating software for performing automatic measurements. Both hardware and software standard cell protection circuits are built-in.

In order to address the increasing demand for automated calibration of DCV ranges of most precise multifunction calibrators, as well as the linearity verification of the long scale DVM’s, the option of fully automated bipolar measurement has been developed. This allows the user to do measurement of ± 10 V range with 8000A and extend it to ± 1200 V when the 8001B extender is used.

Fully documented calibration of bipolar voltages at the output of the calibrator is traceable to laboratory’s 10 V reference standard. Determining the 8000B correction factors and standardizing the source at both polarities gives additional confidence on calibration results.

The model 8000B’s range can be extended to 1200 Volts with Measurements International’s precision divider extender (model 8001B). Latest development HW and SW features of 8000B allows fully automated bipolar measurements without manual intervention. This, in combination with model 8001B extender, brings full automation of DCV ranges calibration and linearity verification of multifunction calibrators and long scale DVM’s at range up to ± 1200 V.

Operation:

The principle of the 8000B Automatic Potentiometer is based on the Binary Voltage Divider (BVD). The BVD requires two voltage references and a DMM detector. The first reference or source is a low drift, stable, noise-free 10 Volt source which is connected to the rear on the 8000B source input. The most important thing about the source is its stability. The reference to the BVD is supplied from a calibrated stable voltage reference, MI model 1000A or Fluke model 732A or B. The source and 8000B are standardized against the calibrated reference for making absolute voltage measurements.

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The DMM detector with an input impedance of 10 G or higher is then used to measure the difference between the output of the BVD and the voltage under test. An isolated guard circuit is provided to guard the BVD and the DMM detector when performing measurements. The guard voltage can also be used to drive the guards of the cell enclosures under test to reduce leakage problems.

8000B Ratio Verification (RVB)

The model 8000B ratio can be calibrated directly against the 10 V Josephson Array or the ratio can be verified by measuring the normal and inverse ratio of two stable resistors using the 8000B Ratio Verification Box.

The RVB contains a low thermal reversing switch and wiring so that the 8000B can be calibrated within its linearity specification. The program is built into the software and all measurements and data are stored to the measurement file. The software also performs the calculations of the ratio of the two resistors and the error of the bridge. Only the short term stability of the resistors is important.