Input Protection

NI Digital Multimeters

Input Protection

The current-measuring circuit is protected with a fuse rated at F 3.15 A 250 V. The NI 4065 and NI 4071 can measure up to 3 A DC or 3 Arms with up to 4.2 A peak current (sine wave only). Higher currents will blow the fuse.

If you apply higher current level to a range, the input protection circuitry of the NI 4065 and NI 4071 automatically engage, and you receive an overrange warning.

Also, keep in mind that exposing the current measurement connectors to voltage sources while the DC or AC current functions are selected may trigger the input protection circuitry or even blow the fuse. Do not apply more than 150 mV to the 1 A and 3 A ranges, or more than 1 V to any of the other ranges.

For more information on fuse replacement, refer to Related Documentation for the NI Digital Multimeters Getting Started Guide.