Download HP 3478A Digital Multimeter

RMS measurements are made by calculating the instantaneous square of the input
signal, averaging it and taking the square root of the result. This provides a DC
voltage that is proportional to the RMS value of the waveform. A DC voltage
measurement is then made by the A/D converter.
It should be noted that the AC voltmeter accuracy is specified only for inputs greater
than 10% of full scale. Hence the specified range is 30 millivolts to 300 volts. The
300 millivolt range is useful for lower accuracy readings down to 1 millivolt. Up to
several hundred counts of residual offset may be seen on the 5 Yz digit display with
the input shorted.
Command
F2
Selects the AC Volts mode (also H2)
fl SENSE
INPUT
14 WIRE I
12 WIRE I
~HI
300V~
MAX
~LO
3A;::::;
MAX
ALLTERM
~500Vpk
~
A
MAX
...J....
=
3A/250V
FUSE
3478-2-5
Figure 2-5. Voltage Measurements
33