Bar Graph; Autorange With "Floor - Fluke 78 User Manual

78
Users Manual

Bar Graph

The bar graph shows readings relative to the full scale
value of a measurement range.
For example, if the meter is in the "4V" range, the scale
goes from 0-4, and each number on the bar graph scale
represents 1 V. If the meter is in the "40V" range, the
scale goes from 0-40, and each number on the scale rep-
resents 10 V.
The range is indicated by a number at the right of the bar
graph; polarity is indicated by a plus (+) or minus (-) sign
at the left. See Figure 3.
The bar graph turns off when the meter is measuring
RPM, duty cycle, dwell, temperature or frequency in the
VDC mode. When measuring frequency in the VAC mode
the meter displays frequency on the digital display and
shows the voltage of the input signal on the bar graph.
This allows you to see if a hazardous AC voltage is pres-
ent.
Some examples of digital readings and their equivalents
on the bar graph are shown in Figure 4.
12

Autorange with "Floor"

For most applications, simply select a function and make
the measurement. The meter "autoranges" to the best
range for the input signal and displays a reading. Most
functions have more than one range (see
SPECIFICATIONS). The range is shown at the right of the
bar graph.
In MIN MAX autorange is disabled. (See "How to
Use MIN MAX ....")
Each range has a "floor". The meter autoranges above the
floor but not below it. To determine the floor, short the test
leads; the floor is shown at the right of the bar graph.
When using Fluke accessories (like a dc current clamp or
pressure sensor), you may want to lock the meter in a mil-
livolt range in which 1 mV equals 1 unit of measurement
(e.g., for pressure measurements, 1 mV could equal 1
psi). See "How to Lock the Meter in a Measurement
Range".
Note