User Manual

True-rms Digital Multimeter
How to Make Measurements
17
When you measure voltage, the Product puts
approximately 10-MΩ (10,000,000 Ω) impedance in
parallel with the circuit. This loading effect can cause
measurement errors in high-impedance circuits. In most
cases, the error is negligible (0.1 % or less) if the circuit
impedance is 10 kΩ (10,000 Ω) or less.
For better accuracy when you measure the dc offset of an
ac voltage, measure the ac voltage first. Record the ac
voltage range, then manually select a dc voltage range
equal to or higher than the ac range. This procedure has
better accuracy of the dc measurement because the input
protection circuits are disabled.
Zero Input Behavior of True-rms Meters
True-rms meters accurately measure distorted
waveforms, but when the input leads are shorted together
in the ac functions, the Product shows a measurement
between 1 and 30 counts. When the test leads are open,
the measurements can change from interference. These
offset measurements are common. They do not change
the ac measurement accuracy of the Product for the
specified measurement ranges.
Unspecified input levels are:
• AC voltage: below 3 % of 600 mV ac, or 18 mV ac
• AC current: below 3 % of 60 mA ac, or 1.8 mA ac
• AC current: below 3 % of 600 μA ac, or 18 μA ac