With guard GRD on, the driven guard is available at the inner shell of the triax connector which is connected to the metal guard plate. The driven guard is used to eliminate leakage current and capacitance in high impedance circuits that could corrupt the volts or ohms measurement. Page Basic Operation 3. Enable or disable guard. Use the GRD key to select depending on guarded or unguarded connections. Perform zero correct volts only.
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The B is also capable of measuring the largest voltage range-up to V-with an input impedance exceeding TO. The voltage circuit input impedance is greater than TO for near-ideal circuit loading. These specifications ensure the accuracy and sensitivity needed for accurate low current and high impedance voltage, resistance, and charge measurements in areas of research such as physics, optics, nanotechnology, and materials science.
Wide Measurement Ranges The B offers autoranging over the full span of ranges on current, resistance, voltage, and charge measurements. While high resistance materials and devices produce very small currents that are difficult to measure accurately, Keithley electrometers and picoammeters are used successfully for such measurements.
Even with high quality instrumentation, inherent background currents in the material can make these measurements difficult to perform accurately. Insulating materials, polymers, and plastics typically exhibit background currents due to piezoelectric effects, capacitive elements charged by static electricity, and polarization effects.
These background currents are often equal to or greater than the current stimulated by the applied voltage. In these cases, the result is often unstable, providing inaccurate resistance or resistivity readings or even erroneous negative values. Alternating Polarity Method for High Resistance Measurements The B uses the Alternating Polarity Method, which virtually eliminates the effect of any background currents in the sample.
First and second order drifts of the background currents are also canceled out. The Alternating Polarity Method applies a voltage of positive polarity, then the current is measured after a specified delay Measure Time. Next, the polarity is reversed and the current measured again, using the same delay.
This process is repeated continuously, and the resistance is calculated based on a weighted average of the four most recent current measurements. This method typically produces a highly repeatable, accurate measurement of resistance or resistivity by the seventh reversal on most materials i.
Simple DMM-like Operation The B is designed for easy, DMM-like operation via the front panel, with single-button control of important functions such as resistance measurement.
High Accuracy High Resistance Measurements The B offers a number of features and capabilities that help ensure the accuracy of high resistance measurement applications. It is wellsuited for capacitor leakage and insulation resistance measurements, tests of the surface insulation resistance of printed circuit boards, voltage coefficient testing of resistors, and diode leakage characterization.
Temperature and Humidity Stamping Humidity and temperature can influence the resistivity values of materials significantly.
To help you make accurate comparisons of readings acquired under varying conditions, the B offers a builtin type K thermocouple and an optional RH Relative Humidity Probe. A built-in 50, reading data storage buffer allows recording and recalling measurements stamped with the time of the measurement, the temperature, and the relative humidity. Internal Test Sequences Expand and Simplify Applications The B has a number of internal test sequences that assists in easily setting up and performing a number of tests.
Device characterization sequences include diode leakage current measurement, capacitor leakage current measurement, cable insulation resistance measurement, and resistor voltage coefficient measurement. Resistivity and resistance tests include volume resistivity, surface resistivity, and surface insulation resistance testing. Parameters can be characterized as a function of voltage with the square wave and staircase test sequences. In addition to its built-in tests, the B excels in low current, high impedance voltage, resistance, and charge measurements in areas of research such as physics, optics, and materials science.
With its highly responsive measurements and DMM-like operation, the B performs well in quality control, design engineering, and production test applications involving leakage current, breakdown, and resistance testing. The B is also excellent for electrochemistry applications such as high impedance, ion-selective electrodes and pH measurements, conductivity cells, and potentiometry.
Keithley 6514 Instruction Manual
Conductivity cells Potentiometry The Keithley Programmable Electrometer combines flexible interfacing capabilities with current sensitivity, charge measurement capabilities, resolution, and speed that are equal or superior to our earlier electrometers. Applications include measuring currents from light detectors and other sensors, beam experiments, and measuring resistances using a current source. The builds on the features and capabilities of the Keithley electrometers that preceded it. For example, like those instruments, a built-in constant current source simplifies measuring resistance. Two analog outputs-a 2V output and a preamp output-are available for recording data with stripchart recorders. Economical Component Testing Once, electrometers were simply considered too slow to keep up with the high throughput that production test applications demand.
Keithley 6514 静电计