Fluke 717, 718, 725, 753, 754 Service Guide

Transmitter Calibration

754

DOCUMENTING PROCESS CALIBRATOR

with the Fluke 750 Series

Documenting Process Calibrator

Application Note

The precision sourcing and measurement
capabilities of the rugged Fluke Documenting
Process Calibrator (DPC) make it an ideal choice
for the calibration of process instrumentation.
The following examples show how to address trans­mitter calibrations quickly and effectively using the
Fluke 753 or 754 Documenting Process Calibrators.

Calibrating a 2 Wire Thermocouple
Transmitter with the Fluke 750 Series
Documenting Process Calibrators

The transmitter in this example is a 2 wire trans­mitter (needs loop power). The input stimulus for
this device is from a type K thermocouple with an
input range of 100 °C to 300 °C at 0 % and 100 %.
The output drawn against loop power is 4-20 mA
at 0 % and 100 % with a tolerance of 0.25 %. The
steps below show how to: 1) perform a three point
ascending (3↑) As Found (pre-adjustment) test at
0-50-100 %, and Tag the results, 2) adjust the
zero and span (span = 100 %) of the transmitter,
then 3) perform a three point ascending As Left
(post-adjustment) test at 0-50-100 %, Tag those
results and review them in memory.

Rosemount 444

1. Connect a type K mini­connector into the “TC” input
of the DPC and connect to
the thermocouple input of
the transmitter (Figure 1). It
is necessary that you use the
correct type of mini-connec­tor for this connection to the
DPC.

2. Connect the center two ter­minals of the DPC to the con­nections on the transmitter
where loop power is applied
(Figure 1).

Note: If you prefer to use house
loop power rather than supplying
loop power from the DPC, connect
these two leads in series with the
loop supply to the transmitter.

3. Once your connections are
made, starting from the DPC
power up state (or measure
screen), select the “mA” but­ton to measure milliamps
(Figure 2).

Figure 2.

4. Next depress the “MEAS/
SOURCE” button; now you are
in the source screen.

Since you want to source a

thermocouple, press “TC/RTD”
once. Press ENTER to select
TC. Use the down arrow to
move the cursor to “K” and
then press “ENTER.” Select
“Linear T” and press ENTER.
The DPC will respond with
????? asking for a tempera­ture to source. Depress “100”
and “ENTER” (Figure 3).

Figure 3.

Figure 1.

TEST DC PWR

++

––

Fluke DPC

5. Next press the “MEAS/
SOURCE” button once and
you will be in the split screen
mode (Figure 4).

Figure 4.

Note: Skip to step 7 if you are
measuring current in series using
the house loop power source
mentioned in step (2).

6. Next, depress the “SETUP”
button on the DPC. The cursor
should begin on loop power.
Depress “ENTER,” down
arrow until the DPC cursor
is on Enabled and depress
“ENTER.” Next depress the
“Done” softkey (Figure 5).

Figure 7.

8. Select “Auto Test,” and watch
the DPC take 0 %, 50 % and
100 % measurements of cur­rent (4, 12 and 20 mA nomi­nal) while sourcing 100 °C,
200 °C and 300 °C.

9. Once the DPC has completed
this evaluation, it will display
the post test summary screen
with the SOURCE, MEASURE
and ERROR columns. Failures
in the error column will be
in reverse video (Figure 8).
Depress “Done.”

0.25 %. As long as the error
exceeds .25 % the error win­dow in the measure half of
the screen will be in reverse
video. Adjust the zero on the
transmitter until the error is
less than 0.25 %. Next, select
“Go to 100 %” and adjust the
transmitter span in the same
way. You may also “Go to
50 %” to check linearity at
mid-span.

12. After adjustment is complete,
select “As Left,” “Done” and
“Autotest.” Watch the 0-50­100 % evaluations. If the
adjustment was successful,
all the errors in the post run
summary should be in normal
video (or less than .25 %)
(Figure 10).

Figure 5.

7. At this point depress
“As Found” and select
“Instrument” and press
“ENTER,” then fill in the
template, use the default
“Delay=0 seconds.”)

Figure 6.

Depress “DONE.” You should

now see the split screen and
are presented with soft key
choices of “Abort,” “Auto
Test,” and “Manual Test”
(Figure 7).

Figure 8.

10. Now you are presented with
the Tag entry screen (Figure 9).

Figure 9.

Press the “ENTER” key to edit

the entries. Depress “Done”
when complete until the split
screen reappears with the
soft key options of “As Left,”
“Adjust,” “Save” and “More
Choices” on the display of the
DPC.

11. At this point, select “Adjust”
and the DPC will source 0 %
and measure for 4 mA to

Figure 10.

13. Select “Done,” “Done,” and
“Done” again and you are
done!

To review your results
in memory, select the “More
Choices” soft key, the “Review
Memory” soft key and move your
cursor to the applicable result and
press enter. Select “As Found”
or “As Left,” then “ENTER” and
review the setup for the test,
select “Next Page” for the results,
and press “Tag” for its associated
label. Select “Done” and “Done”.
Move your cursor to the applicable
“As Left” result and press “ENTER”
and review the test setup, select
“Next Page” for the results, and
press “Tag” for its associated
label. When you are finished
reviewing results, press “Done”
until right-most soft key label
changes to “More Choices.”

2 Fluke Corporation 750 Series Documenting Process Calibrators

3 and 4 Wire RTD Sourcing for the Fluke 750 Series

754

DOCUMENTING PROCESS CALIBRATOR

TEST DC PWR

++

––

Fluke DPC

C-2

C-1

S-3

S-2

S-4

S-1

Documenting Process Calibrators

One of the most frequently asked application questions pertaining to
the 750 Series Documenting Process Calibrators is, “How do I hook
up the test leads to the DPC to source 3 and 4 wire RTDs?” For 3 and
4 wire RTD measurement, the DPC has embedded hookup diagrams
that easily show you how to connect the DPC. However, for 3 and 4
wire RTD source, the DPC does not offer that assistance.

The example shown below (Figure 11) depicts the hookup for a 3
and 4 wire Rosemount 444 RTD Transmitter. You will need an addi­tional pair of TL22 test leads and AC20 industrial test clips to complete
all the connections necessary for this application. In order to double
the available connections to the source terminals on the DPC, you also
will need to utilize the short black jumpers supplied with the Docu­menting Process Calibrator.

1. Make the RTD source

connections, S1, S2, S3 and
S4 (omit S3 and S4 for 2 wire
RTDs and S4 for 3 wire RTDs;
S4 is only needed for 4 wire
RTD sourcing).

2. Next, connect the loop power

and current measurement
connections, C1 and C2.

Figure 11.

3. Once the connections are
made as per the diagram in
Figure 11, enable the loop
24 volt power from the setup
screen, source the pertinent
RTD for the specific transmit­ter being evaluated, and set
the measure mode to mA.

4. At this point, enter the split
screen mode of the DPC and
perform the As Found, Adjust
and As Left tests as you did
in the previous thermocouple
transmitter example.

Fluke Corporation 750 Series Documenting Process Calibrators 3