7½ Digit Multimeter User's Manual Section 5:
Measuring DC voltage with high accuracy
DMM7510-900-01 Rev. C / September 2019 5-3
To prevent electric shock, test connections must be configured such that the user cannot
come in contact with test leads or any device under test (DUT) that is in contact with the
conductors. It is good practice to disconnect power before connecting DUTs. Safe installation
requires proper shields, barriers, and grounding to prevent contact with test leads.
There is no internal connection between protective earth (safety ground) and the LO
terminals of the DMM7510. Therefore, hazardous voltages (more than 30 V
RMS
) can appear on
LO terminals. This can occur when the instrument is operating in any mode. To prevent
hazardous voltage from appearing on the LO terminals, connect the LO terminal to protective
earth (safety ground) if your application allows it. You can connect the LO terminal to the
chassis ground terminal on the front panel or the chassis ground screw terminal on the rear
panel. Note that the front-panel terminals are isolated from the rear-panel terminals.
Therefore, if you are using the front-panel terminals, ground to the front-panel LO terminal. If
using the rear-panel terminals, ground to the rear-panel LO terminal. Failure to follow these
guidelines can result in injury, death, or instrument damage. Failure to recognize and observe
normal safety precautions could result in personal injury or death.
High-accuracy DC voltage measurements
This application demonstrates how to use the DMM7510 to make a high-accuracy DC voltage
measurement. You can make the measurement from the front panel or over the remote interface
using SCPI code or TSP code. For information about setting up remote communications, see
Remote
communications interfaces (on page 3-1).
For this application, you will:
• Restart the instrument.
• Select the DC voltage function.
• Set the integration rate to 10 power line cycles (PLCs). At 60 Hz line frequency, 10 PLCs provide
an aperture of 166.7 ms.
• Set the input impedance to Auto.
• Turn on autozero. This enables the instrument to optimize the accuracy of readings by checking
reference measurements.
• Enable a repeating filter with a count of 100. This reduces noise error because the results are
more stable when the measurements are averaged.
• Generate readings from the front panel or the remote interface.
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