Fluke 789, Руководство пользователя, Страница: 30 / 54

789
Users Manual
22
Simulate Mode
Simulate mode is so named because the meter simulates
a current loop transmitter. Use simulate mode when an
external dc voltage of 15 to 48 V is in series with the
current loop under test.
W
Caution
Set the rotary function switch to one of the
mA output settings BEFORE connecting the
test leads to a current loop. Otherwise, a low
impedance from the other rotary function
switch positions could be presented to the
loop, causing up to 35 mA to flow in the loop.
Simulate mode is selected automatically by inserting the
test leads into the SIMULATE
+
and
−
jacks as shown in
Figure 8. Simulate mode conserves battery life, so use it
instead of source mode whenever possible.
The display looks the same in source and simulate modes.
The way to tell which mode is in use is to see which pair
of output jacks is in use.
Changing the Current Span
The meter’s current output span has two settings (with
overrange to 24 mA):
•
4 mA = 0 %, 20 mA = 100 % (factory default)
•
0 mA = 0 %, 20 mA = 100 %
To find out which span is selected, short the OUTPUT
SOURCE
+
and
−
jacks, turn the rotary function switch to
OUTPUT
[
mA, and observe the 0 % output level.
To toggle and save the current output span in nonvolatile
memory (retained when the power is turned off):
1. Turn off the meter.
2. Hold down
R
while turning the meter on.
3. Wait at least 2 seconds, then release
R
.