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.

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.

1378

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.

Table 8. 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.

The following table lists the functions and ranges supported for waveform acquisitions:

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 Current1 20 mA, 200 mA, 1 A
AC Current1 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/Period2 1 Hz - 500 kHz / 2 µs - 1 s
Capacitance 300 pF, 1 nF, 10 nF, 100 nF, 1 µF, 10 µF, 100 µF, 1,000 µF, 10,000 µF
Inductance 10 µH, 100 µH, 1 mH, 10 mH, 100 mH, 1 H, 5 H

1To 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.

2Frequency/Period voltage ranges are the same as AC voltage ranges.

The following table lists the available NI 4072 input resistance selections. NI calibrates the NI 4072 for full accuracy with all input resistances shown.

Waveform Function Ranges Coupling
Voltage Waveform 100 mV, 1 V, 10 V, 100 V, 300 V AC or DC
Current Waveform1 20 mA, 200 mA, 1 A DC
1To 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.
Note   The default input resistance for each range is italicized.

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 Calibration Executive, refer to the NI Calibration Solutions Web site. All NI measurement devices receive NIST-traceable calibration before shipping.