NI 4072
The NI 4072 is a 6½ digit DMM for the PXI bus. The NI 4072 can take capacitance and inductance measurements and can acquire waveforms at 1.8 MS/s. For more information about the NI 4072 specifications, refer to Related Documentation for the NI 4072 specifications document.
This topic contains the following subsections:
Impedance
The NI 4072 uses a 2-wire, AC-current technique to measure capacitance and inductance. A current source (Isrc) is supplied to the device under test (DUT), and the NI 4072 determines the measured voltage (Vm), as shown in the following figure.
With a known current and voltage, the NI 4072 determines the capacitance or inductance of the DUT if the residual serial impedance (Zs) and the stray parallel impedance (Yp) are small or negligible compared to the DUT. If (Zs) and (Yp) introduce a significant error into the measurement, the NI 4072 can measure the error and reduce it using compensation techniques. For more information, refer to the OPEN/SHORT Compensation section.
For the measurement ranges for the capacitance and inductance modes on the NI 4072, refer to Related Documentation for the NI 4072 specifications document.
Interconnects and Cables
The front of the NI 4072 module has five connectors—four banana plug connectors and one 9-pin mini–circular DIN connector. The four banana plug connectors are high-voltage, safety-agency approved signal connectors. The 9-pin DIN connector labeled AUX I/O is a digital signal connector, which carries triggers and SCXI communication signals. For an illustration of the front panel connectors and wiring instructions, refer to Front Panel Connections topic for the NI 4072.
The input connectors on the NI 4072 are gold-plated, low-thermal copper for best low-voltage performance. The insulator material is a Lexan compound, optimized for low leakage over the full environmental operating range.
For use with the NI 4072, NI recommends selecting a cable with characteristics similar to the Belden 83317E, which is available at www.belden.com. Tape-wrapped polytetrafluoroethylene (PTFE) insulation guarantees low leakage. Copper conductors with silver plating perform very well for low-voltage measurements because of their low thermal characteristics. Use a cable with at least 90% shielding effectiveness.
Belden #83317E Teflon Insulated Cable
| Type of Insulator | AWG | Conductor Material | Resistance per Foot | Capacitance per Foot |
|---|---|---|---|---|
| TFE | 26 | Silver-plated copper, stranded | 39 mΩ | 35.5 pF |
Operation
The NI 4072 can operate as a DMM and can acquire waveforms up to 1.8 MS/s. The following table lists the functions and ranges supported by the NI 4072 while in DMM mode.
| DMM Function | Ranges |
|---|---|
| DC Voltage | 100 mV, 1 V, 10 V, 100 V, 300 V |
| AC Voltage | 50 mV, 500 mV, 5 V, 50 V, 300 V |
| DC Current* | 20 mA, 200 mA, 1 A |
| AC Current* | 10 mA, 100 mA, 1 A |
| 2-Wire Resistance | 100 Ω, 1 kΩ, 10 kΩ, 100 kΩ, 1 MΩ, 10 MΩ, 100 MΩ |
| 4-Wire Resistance | 100 Ω, 1 kΩ, 10 kΩ, 100 kΩ, 1 MΩ, 10 MΩ |
| Diode | 10 V at 1 µA / 10µA / 100µA; 4.5 V at 1 mA |
| Frequency/Period | 50 mV, 500 mV, 5 V, 50 V, 300 V |
| Capacitance | 300 pF, 1 nF, 10 nF, 100 nF, 1 µF, 10 µF, 100 µF, 1,000 µF, 10,000 µF |
| Inductance | 10 uH, 100 uH, 1 mH, 10 mH, 100 mH, 1 H, 5 H |
| * To measure current outside of the normal range on the NI 4072, you must use a current shunt module (CSM). Refer to Measuring Current for more information. | |
The following table lists the functions and ranges supported for waveform acquisitions:
| Waveform Function | Ranges | Coupling |
|---|---|---|
| Voltage Waveform | 100 mV, 1 V, 10 V, 100 V, 300 V | AC or DC |
| Current Waveform* | 20 mA, 200 mA, 1 A | DC |
| * To measure current outside of the normal range on the NI 4072, you must use a current shunt module (CSM). Refer to the Measuring Current section for more information. | ||
Additional Features
- Self-Calibration
- Auto Zero
- Configuring Auto Range
- Offset Compensated Ohms
- ADC Calibration
- Input Resistance
- Configuring Measurement Timing
- Aperture Time
- DC Noise Rejection
- Waveform Acquisitions
- Single Point Acquisitions
- Generating Measurement Complete
- Scanning Switch Modules
Replacing the Fuse
The NI 4072 is equipped with a F 1.25 A 250 V Fast–Acting fuse designed to help protect the DMM and your test system. For instructions on replacing the fuse, refer to Related Documentation for the NI Digital Multimeters Getting Started Guide.
Calibrating the NI 4072
Calibration maximizes the accuracy of a DMM. To ensure accuracy, you must perform calibration. NI recommends that you externally calibrate every two years. Refer to the NI 4070/4072 6½ Digit FlexDMM Calibration Procedure at the NI Calibration Solutions Web site for information on externally calibrating the NI PXI/PCI-4070/4072. For information on calibrating the NI 4072 using National Instruments Calibration Executive, refer to the NI Calibration Solutions Web site. All NI measurement devices receive NIST-traceable calibration before shipping.