What makes the Fluke 787 different
than the Fluke 87 ?
The main difference is the Source/Simulate current
modes. These modes provide either a mA Source mode (drawn from internal power) or a mA
Simulate mode (power supplied from an external loop supply with current flow controlled by
the 787). Also, to make room for the precision 30,000 count current calibration circuits
(and after extensive customer surveys) the following Fluke-87 features were changed:
Current resolution is now 1 mA, versus the 87’s 10 mA resolution.
Frequency to 20 kHz selectable via button control
No Capacitance or duty cycle functions
The peak-hold function was removed.
1 Amp max instead of 10A max current measurement
Display has % of Span reading in place of the 87 style bar graph
Removable battery door; no need for re-calibration after battery changes
Why should an Instrument Shop Supervisor buy a
Fluke 787?
Instrumentation technician productivity is the main
reason. With the Fluke 787, the technician has a loop calibrator as well as a DMM, to
instantly tackle almost any loop troubleshooting or calibration task. That means fewer
long walks back to the shop for additional tools. Another reason is lower ownership costs.
The 787 simply costs less to buy and own than a separate DMM and loop calibrator.
How does the price of the Fluke 787 compare to the
combined price of a separate DMM and Loop Calibrator?
Typically, the combined price of a professional
quality DMM and loop calibrator is 50% higher than the price of a single Fluke 787. Some
popular loop calibrators alone now exceed the price of a 787.
Why should Instrumentation Technicians choose the
Fluke 787?
The new 787 is the latest version of the 80 Series
DMM you already use and trust. The 787 has been optimized for use on 20 mA current control
loops, and offers these advantages over present tools:
1 mA resolution and 0.05% accuracy on mA source, simulate, or measure
Simultaneous viewing of both mA and % of span
Instantaneous 25% steps for mA source or simulate
Auto ramp and auto step of mA source or simulate
External battery door, for quick battery changes
Backlight, for use in all light conditions
Rugged reliability you expect from Fluke
What is the largest load the current Source /
Simulate mode can drive?
Any load that does not require more than 24 mA and
does not drop over 12 V. As an example , if you have a 1000 Ohm load then you can only put
12 mA through it (1000 Ohm X 12 mA = 12 V ) ; at 12 V/ 24 mA = 500 Ohms is the largest
load. In current simulate mode, using a 30 V supply, load figures change to 30V / 24 mA =
1250 Ohms.
When I change the battery do I have to
re-calibrate the 787 ?
No, thanks to the external battery door, the main
body of the 787 remains closed . This does not require re-calibrating the unit as may be
the case with some DMMs. The recommended calibration time for the 787 is 1 year. (Three
year warranty)
What are the step levels for the “%
step” , “Coarse, and “Fine”
in current output mode ?
When in the 4-20 mA mode, the STEP button
increments in 4 mA steps. When set to the 0 - 20 mA mode the increment level is 5 mA. In
all modes the COARSE and FINE adjustments are 0.1 mA steps and 1 mA steps
What ramp functions are available in the 787 ?
There are three basic ramp functions on the 787.
These functions operate in both current Source and Simulate mode. Two of the ramp
functions slew current output repeatedly, from zero to span and back to zero The Slow ramp
rate is a 60 second cycle , the Fast ramp rate is a 20 second cycle. A stair-step ramp
function is also available. Each step level is 25% of selected span ( 0-20 mA or 4-20 mA)
and pauses for 5 seconds at each level.
