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18
Operation
2.3 Measurement of DC Volts
The 918B can measure dc voltages of between 0.2 and 1000 volts.
For measurement of dc voltage, the current input is not used.
CAUTION
Do not exceed
±
25 volts peak, with respect to earth
ground, on the (-) voltage input. The 918B is designed to operate
with the (-) input connected to earth ground or circuit neutral.
Procedure
1.
Switch the unit into the dc voltage mode by first pressing the
"SHIFT" key, then pressing "Vdc".
2.
Plug the supplied test probes into the voltage input terminals,
with the red wire connected to the (+) terminal and the black
wire connected to the (-) terminal.
3.
Connect the black lead to the circuit neutral or ground, or the
point to be used as the reference for the measurement.
4.
Connect the red test lead to the voltage to be measured. The
voltage present between the two test leads will be indicated on
the front panel display.
Voltage Ranges
For the voltage input, the 918B has four different operating ranges.
Depending on the level of voltage applied to the input, the
instrument may automatically switch between ranges. This range
switching is internal, and may or may not be evident in the display.
Automatic range switching can be defeated, using range hold. Refer
to section 3.1, "Automatic and Manual Range Selection", for a
description of the internal ranges, the display ranges, auto-ranging
operation, and range hold operation.