With a measurement range from 100 kΩ to 20 PΩ, the 6540 resistance bridge provides two measurement modes. Bridge Mode allows technicians to use a reference standard and multiple ratios for best uncertainty, or Direct Mode allows a resistance to be measured without a reference standard. The Bridge Mode uses a standard reference resistor and compares the known value to the resistance being measured via ratio measurements. The available range of ratios is from 1:1 to 100:1 for the reference resistors. These ratio measurements are similar to a dual source bridge in that the reference resistor and unknown resistor are connected at the same time. The 6540 Direct Measurement model allows the instrument to measure an unknown resistance without requiring a reference standard. The 6540 incorporates an advanced innovative design that dramatically simplifies operation, provides automation, and significantly reduces life cycle support of high resistance measurements. In normal laboratory environments, the 6540 provides much better uncertainties than any other commercial high resistance measurement instrument available today.
