Can the NI PXI-4072 FlexDMM & LCR Meter Perform Impedance Measurements?Hardware: Modular Instruments>>Digital Multimeters (DMM)>>PXI-4072
Problem: I have a circuit that is comprised of inductive, capactive, and resistive elements. Can I use the NI 4072 to perform an overall impedance measurement of this circuit? Solution: No, the NI 4072 is designed to measure these circuit elements seperately. Furthermore, to ensure measurement accuracy, the load that is measured should be as close to purely inductive, capacitive, or resisitve as possible. Resistance measurements The NI 4072 makes resistance measurements using a constant-current technique. A current is supplied to the resistance under test, and the DMM measures the resulting voltage as represented in the following figure.  Capacitance/Inductance measurements The 4072 uses a multi-tone AC current source as the excitation signal necessary to measure capacitance and inductance. The current waveform is a very stable, harmonically limited square wave which is applied to the device.  When the current and voltage are known, the NI 4072 calculates the capacitance or inductance using FFT peak analysis. If the residual series impedance (Zs) and the stray parallel admittance (Yp) introduce a significant error in the measurement, the NI 4072 can measure the magnitude of the error and reduce it using cable compensation techniques. For further information regarding the test signals and model used to measure capacitive and inductive circuit elements, see the NI Digital Multimeters Help under the Devices » NI 4072 » DMM Measurements » Capacitance/Inductance section. For more information regarding cable compensation, see the Devices » NI 4072 » DMM Measurements » Capacitance/Inductance » OPEN/SHORT Compensation section. Related Links: NI Digital Multimeters Help Attachments:  
Report Date: 09/27/2006 Last Updated: 03/28/2008 Document ID: 41QG9ALA |
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