Response Times - Fluke 45 User Manual

45
Users Manual
CIRCUIT
The lead from the internal measuring circuitry of the meter to the COM binding post (on
the front panel) is the same for both voltage and current measurements. The resistance of
this lead is approximately .003 . If current is being measured, therefore, a voltage drop
will occur in the resistance that is common to both circuits. This internal resistance, when
added to the external resistance of the lead from the COM input terminal will affect the
accuracy of the voltage reading. For instance, if the external lead resistance is .007 , the
"total" common resistance is .010 . If there is 1 A of current, the voltage reading would
be affected by
Depending on the circumstances, this may be significant.
If you want to measure dc voltage on an input signal in the primary display and dc
current in the secondary display, proceed as follows:
1. Turn the meter on.
2. Press
3. Press
4. Connect the leads to the test circuit as shown in Figure 4-2 and read the

Response Times

Response time is the time between a change in an input and when that change is displayed.
The meter's response time depends on many factors: the measurement function selected,
number of measurements being made (single measurement when only the primary display is
used, or two measurements when both the primary and secondary display are used), the input
4-4
LOAD
Figure 4-2 DC Voltage and DC Current Measurement on Input Signal
(1 A x.01 ) = .01 V or 10 m V.
to select the dc voltage function for the primary display.
, then press
measurements on the displays. Although current will be displayed as negative, it is in
fact positive when interpreted according current flow convention.
V
10A
600V CAT I !
1000V CAT I
100
COM
mA
FUSE F1
V
A
500 mA
F 250V
FUSED
V A
V
to select the dc current function for the secondary display.
45 DUAL DISPLAY MULTIMETER
REL dB
REF# REF
AUTO
FREQ
HOLD MN MX
COMP HI LO THRESH ADDR
POWER
2ND
A
CAL
ENABLE
2ND
LOCAL
RATE
BAUD
aam17f.eps