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Fluke 789 User Manual Download Page 37

ProcessMeter

Loop Power Supply Mode

29

Loop Power Supply Mode

The Loop Power Supply Mode can be used for powering
up a process instrument (transmitter). While in Loop
Power Mode, the meter acts like a battery. The process
instrument regulates the current. At the same time, the
meter measures the current that the process instrument is
drawing.

The meter supplies loop power at a nominal 24 V dc. An
internal series resistance of 250

Ω

can be switched in for

communication with HART and other smart devices by
pressing

J

(Blue). Pressing

J

(Blue). again switches out

this internal resistance.

When loop power is enabled, the meter is configured to
measure mA and > 24 V dc is sourced between the mA
and A jacks. The mA jack is the common and the A jack is
at > 24 V dc. Connect the meter in series with the
instrument current loop as Figure 10 shows.

32

30

28

26

24

22

20

0

4

8

12

16

20

24

Loop voltage w/ 250

Loop voltage w/o 250

Voltage (V)

Current (mA)

anw020f.eps

Figure 9. Loop Power Voltage vs. Current

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Summary of Contents for 789

Page 1: ...cessMeter Users Manual August 2002 Rev 2 11 09 2002 2009 Fluke Corporation All rights reserved Specifications are subject to change without notice All product names are trademarks of their respective companies ...

Page 2: ...ice center to obtain return authoriza tion information then send the product to that Service Center with a description of the problem THIS WARRANTY IS YOUR ONLY REMEDY NO OTHER WARRANTIES SUCH AS FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSED OR IMPLIED FLUKE IS NOT LIABLE FOR ANY SPECIAL INDIRECT INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES ARISING FROM ANY CAUSE OR THEORY Since some states or c...

Page 3: ...asuring Electrical Parameters 18 Input Impedance 18 Ranges 18 Testing Diodes 18 Displaying Minimum Maximum and Average 19 Using AutoHold 19 Compensating for Test Lead Resistance 20 Using the Current Output Functions 20 Source Mode 20 Simulate Mode 22 Producing a Steady mA Output 24 Manually Stepping the mA Output 25 Auto Ramping the mA Output 26 ...

Page 4: ... Power Up Options 27 Loop Power Supply Mode 29 Battery Life 31 Maintenance 31 General Maintenance 31 Calibration 31 Replacing a Fuse 34 If the Meter does not Work 34 Replacement Parts and Accessories 35 Specifications 39 ...

Page 5: ...ch Positions for Measurements 9 4 Rotary Function Switch Positions for mA Output 11 5 Rotary Function Switch Position for Loop Supply 11 6 Pushbuttons 13 7 Display 16 8 mA Output Adjust Pushbuttons 25 9 mA Stepping Pushbuttons 26 10 mA Step Values 26 11 Power Up Options 28 12 Typical Alkaline Battery Life 31 ...

Page 6: ...789 Users Manual iv ...

Page 7: ...tions for Measurements 8 4 Rotary Function Switch Positions for mA Output 10 5 Pushbuttons 12 6 Elements of the Display 15 7 Sourcing Current 21 8 Simulating a Transmitter 23 9 Loop Power Voltage vs Current 29 10 Connections for Supplying Loop Power 30 11 Replacing the Batteries and Fuses 33 12 Replacement Parts 36 ...

Page 8: ...789 Users Manual vi ...

Page 9: ...missing contact the place of purchase immediately Contact a Fluke distributor for information about DMM digital multimeter accessories To order replacement parts or spares see Table 13 near the end of this manual Contacting Fluke To contact Fluke call one of the following telephone numbers Technical Support USA 1 800 44 FLUKE 1 800 443 5853 Calibration Repair USA 1 888 99 FLUKE 1 888 993 5853 Cana...

Page 10: ...equipment under test International symbols used on the meter and in this manual are explained in Table 1 XWWarning To avoid possible electric shock or personal injury Do not use the meter if it is damaged Before using the meter inspect the case Look for cracks or missing plastic Pay particular attention to the insulation surrounding the connectors Make sure the battery door is closed and latched b...

Page 11: ...k hazard When using the probes keep fingers behind the finger guards on the probes Connect the common test lead before connecting the live test lead When disconnecting test leads disconnect the live test lead first WCaution To avoid possible damage to meter or to equipment under test Disconnect the power and discharge all high voltage capacitors before testing resistance or continuity Use the prop...

Page 12: ...ted and licensed by TÜV Product Services CAT III IEC Overvoltage Category III Category III equipment is designed to protect against transients in equipment in fixed equipment installations such as distribution panels feeders and short branch circuits and lighting systems in large building Conforms to relevant Australian standards CAT IV IEC Overvoltage Category IV CAT IV equipment is designed to p...

Page 13: ...tions referenced in the previous paragraph The sections following Using the Current Output Functions contain information about the power up options and battery and fuse replacement instructions Later use the Product Overview to refresh your memory about the various functions and features that can be used mA mA mA mA mV V V A LOOP POWER 250 HART OFF mA A COM V Rotary Switch 0 RANGE HOLD REL MIN MAX...

Page 14: ...re 3 and Table 3 describe the input functions of the first six rotary function switch positions Figure 4 and Tables 4 and 5 describe the output functions of the last three rotary function switch positions Figure 5 and Table 6 describe the functions of the pushbuttons Figure 6 and Table 7 explain what all the elements of the display indicate 1 3 4 2 mA A COM V CAT IV 600 V anw001f eps Figure 2 Inpu...

Page 15: ...use Output for dc current to 24 mA Output for loop power supply B mA d Input for current to 30 mA Fused with a 440 mA fuse Common for dc current output to 24 mA Common for loop power supply Output for transmitter simulation to 24 mA Use in series with an external loop supply C V Input for voltage to 1000 V Ω continuity and diode test D COM Common for all measurements Common for transmitter simulat...

Page 16: ...789 Users Manual 8 mA mA mA mA mV V V A LOOP POWER 250 HART OFF 2 3 4 1 6 5 anw002f eps Figure 3 Rotary Function Switch Positions for Measurements ...

Page 17: ... auto range H Toggles AutoHold r Toggles relative reading sets a relative zero point C T Default Measure dc V h Frequency counter Same as above D U Default Measure dc mV h Frequency counter Same as above E V Default Measure Ω G for continuity J Blue D test Same as above except diode test has only one range F W High test lead in cA Measure A dc J Blue selects ac High test lead in dmA Measure mA dc ...

Page 18: ...789 Users Manual 10 mA mA mA mA mV V V A LOOP POWER 250 HART OFF 2 3 1 anw008f eps Figure 4 Rotary Function Switch Positions for mA Output ...

Page 19: ...TPUT Y onp Test leads in SOURCE Source repeating 0 100 0 slow ramp Test leads in SIMULATE Sink repeating 0 100 0 slow ramp J Blue cycles through Fast repeating 0 100 0 ramp o on display Slow repeating 0 100 0 ramp in 25 steps n on display Fast repeating 0 100 0 ramp in 25 steps pon display Slow repeating 0 100 0 ramp on display Table 5 Rotary Function Switch Position for Loop Supply No Position De...

Page 20: ...789 Users Manual 12 6 7 0 RANGE HOLD REL MIN MAX STEP COARSE FINE SpanCheck Hz 100 3 2 1 9 10 8 4 5 anw003f eps Figure 5 Pushbuttons ...

Page 21: ...mA C F Span Check mA Output Sets mA output to 100 value 20 mA D X M STEP Measuring Selects a MIN MAX or AVG action mA Output Adjusts mA output up to the next higher 25 step E X R COARSE Measuring Selects a fixed range hold for 1 second for auto range mA Output Adjusts output up 0 1 mA F X H FINE Measuring Toggles AutoHold or in MIN MAX recording suspends recording mA Output Adjusts output up 0 001...

Page 22: ... test function D Rotary function switch in OUTPUT Y onp position cycles through Slow repeating 0 100 0 ramp on display Fast repeating 0 100 0 ramp o on display Slow repeating 0 100 0 ramp in 25 steps p on display Fast repeating 0 100 0 ramp in 25 steps pon display Rotary function switch in loop supply position Switch in out 250 Ω series resistor I COARSE r W Measuring Toggles relative reading sets...

Page 23: ...ProcessMeter Getting Acquainted with the Meter 15 12 13 15 14 3 4 5 6 8 7 11 2 1 17 16 9 10 anw004f eps Figure 6 Elements of the Display ...

Page 24: ... on F B Lights when the battery is low G q Lights when the meter is transmitting or receiving over the IR port H Numerals Show the input or output value IK lI Lights when AutoHold is on J D Lights in diode test function K I Lights when MIN MAX recording is held L N MAX MINAVG MIN MAX recording status indicators N MIN MAX recording is on MAX the display is showing the maximum recorded value MIN the...

Page 25: ... Range the range is fixed N 400100030 mV The number plus the unit and multiplier indicate the active range O o np One of these lights in mA ramping or step output rotary function switch position Y o np slow continuous 0 100 0 ramping 40 seconds o fast continuous 0 100 0 ramping 15 seconds n slow ramp in 25 steps 15 seconds step p fast ramp in 25 steps 5 seconds step P 250 Ω HART Lights when 250 Ω ...

Page 26: ...the meter will not be displaying its most precise measurement The meter normally selects the lowest range that will measure the applied input signal Auto Range showing on the display Press R to lock the range Each time R is pressed the meter selects the next higher range At the highest range it returns to the lowest range If the range is locked the meter resumes auto ranging when it is changed to ...

Page 27: ...old M for 1 second to erase stored measurements and exit If MIN MAX recording is on continuously for over 40 hours minimum and maximum readings are still recorded but the displayed average no longer changes In MIN MAX recording press H to suspend recording press H again to resume recording Using AutoHold Note MIN MAX recording must be off to use AutoHold Warning To avoid possible electric shock do...

Page 28: ...t for testing 0 20 mA and 4 20 mA current loops Choose source mode in which the meter supplies the current simulate mode in which the meter regulates current in an externally powered current loop or loop supply mode where the meter powers an external device and measures the loop current Source Mode Source mode is selected automatically by inserting the test leads into the SOURCE and jacks as shown...

Page 29: ...rrent Output Functions 21 mA mA mA mA mV V V A LOOP POWER 250 HART OFF mA A COM V 0 RANGE HOLD REL MIN MAX STEP COARSE FINE SpanCheck Hz 100 789 PROCESSMETER 40 20 0 100 80 60 CAT IV 600 V anw010f eps Figure 7 Sourcing Current ...

Page 30: ... 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...

Page 31: ...tions 23 mA mA mA mA mV V V A LOOP POWER 250 HART OFF mA A COM V 0 RANGE HOLD REL MIN MAX STEP COARSE FINE SpanCheck Hz 100 789 PROCESSMETER dc V Power Supply 40 20 0 100 80 60 COM 24V CAT IV 600 V anw011f eps Figure 8 Simulating a Transmitter ...

Page 32: ...n Table 8 Select either sourcing or simulating by choosing the SOURCE or SIMULATE output jacks If the meter cannot deliver the programmed current because the load resistance is too high or the loop supply voltage is too low dashes appear on the numeric display When the impedance between the SOURCE jacks is low enough the meter will resume sourcing Note The STEP pushbuttons described Table 9 are av...

Page 33: ...eter begins sourcing or simulating 0 Use the pushbuttons to step the current up and down in 25 increments as shown in Table 9 See Table 10 for mA values at each 25 step Select either sourcing or simulating by choosing the SOURCE or SIMULATE output jacks If the meter cannot deliver the programmed current because the load resistance is too high or the loop supply voltage is too low dashes appear on ...

Page 34: ...each span setting Step 4 to 20 mA 0 to 20 mA 0 4 000 mA 0 000 mA 25 8 000 mA 5 000 mA 50 12 000 mA 10 000 mA 75 16 000 mA 15 000 mA 100 20 000 mA 20 000 mA 125 24 000 mA 120 24 000 mA Auto Ramping the mA Output Auto ramping gives the ability to continuously apply a varying current stimulus from the meter to a transmitter while hands remain free to test the response of the transmitter Select either...

Page 35: ... J Blue to cycle through the four waveforms Note At any time during auto ramping the ramp can be frozen simply by moving the rotary function switch to the mA position Then the COARSE FINE and STEP adjust pushbuttons can be used to make adjustments Power Up Options To select a power up option hold down the pushbutton shown in Table 11 while turning the rotary function switch from OFF to any on posi...

Page 36: ...4 20 mA range Disable beeper G Enabled Disables beeper Disable auto power off J Blue Enabled Disables the feature that turns off the meter power after 30 minutes of inactivity Auto power off is disabled regardless of this option if MIN MAX recording is on Display test show firmware version H Disabled Display HOLD as long as button is pushed then shows firmware version ...

Page 37: ...An internal series resistance of 250 Ω can be switched in for communication with HART and other smart devices by pressing J Blue Pressing J Blue again switches out this internal resistance When loop power is enabled the meter is configured to measure mA and 24 V dc is sourced between the mA and A jacks The mA jack is the common and the A jack is at 24 V dc Connect the meter in series with the inst...

Page 38: ...d TEST DC PWR Black mA mA mA mA mV V V A LOOP POWER 250 HART OFF mA A COM V 0 RANGE HOLD REL MIN MAX STEP COARSE FINE SpanCheck Hz 100 789 PROCESSMETER CAT IV 600 V anw009f eps Figure 10 Connections for Supplying Loop Power ...

Page 39: ...pical Alkaline Battery Life Meter Operation Hours Measuring any parameter 140 Simulating Current 140 Sourcing 12 mA into 500 Ω 10 Maintenance This section provides some basic maintenance procedures Repair calibration and servicing not covered in this manual must be performed by qualified personnel For maintenance procedures not described in this manual contact a Fluke Service Center General Mainte...

Page 40: ... as follows Refer to Figure 11 Use four AA alkaline batteries 1 Remove the test leads and turn the meter OFF 2 With a standard blade hand screwdriver turn each battery door screw counterclockwise so that the slot is parallel with the screw picture molded into the case 3 Lift off the battery door 4 Remove the meter s batteries 5 Replace with four new AA alkaline batteries 6 Reinstall the battery do...

Page 41: ...ProcessMeter General Maintenance 33 F2 F1 anw037 eps Figure 11 Replacing the Batteries and Fuses ...

Page 42: ...4 Ω the fuse is good An open means that fuse F2 is blown If a fuse is blown replace it as follows Refer to Figure 11 as necessary 1 Remove the test leads from the meter and turn the meter OFF 2 With a standard blade hand screwdriver turn each battery door screw counterclockwise so that the slot is parallel with the screw picture molded into the case 3 Remove either fuse by gently prying one end lo...

Page 43: ...vice Center for information and price Replacement Parts and Accessories Warning To avoid personal injury or damage to the meter use only the specified replacement fuse 440 mA 1000 V fast blow Fluke PN 943121 Note When servicing the meter use only the replacement parts specified here Replacement parts and some accessories are shown in Figure 12 and listed in Table 13 Many more DMM accessories are a...

Page 44: ...789 Users Manual 36 18 26 17 22 23 30 27 19 29 28 24 25 20 21 9 4 12 5 6 8 10 7 3 2 16 15 14 13 11 1 anw005f eps Figure 12 Replacement Parts ...

Page 45: ...P8 Decal Top Case 1623923 1 D MP6 Keypad 1622951 1 E MP5 Top Shield 1622924 1 F MP47 Top Shield Contact 674853 1 G MP4 Contact Housing 1622913 1 H MP28 31 RSOB Contact 1567683 4 I F1 F2 Fuse 440 mA 1000 V fast blow 943121 2 J H7 8 PCB Screw 832220 2 K MP9 Bottom Shield 1675171 1 L MP12 IR Lens 658697 1 M MP40 41 LCD Connectors Elastomeric 1641965 2 N MP7 Backlight Bracket 1622960 1 O P1 LCD Displa...

Page 46: ...r 948609 2 V MP13 Tilt Stand 659026 1 W MP15 Accessory Mount with Probe Holders 658424 1 X MP2 Access Door Battery Fuse 1622870 1 Y MP46 Shock Absorber 674850 1 Z MP16 18 Battery Contacts Dual 666435 3 a MP19 Battery Contact Positive 666438 1 b H3 6 Case Screws 1558745 4 c MP21 Calibration Label 948674 1 d MP22 Calibration Keypad 658689 1 Not shown TL71 Test Leads 1274382 1 set of 2 Not shown AC72...

Page 47: ...r Note Counts refers to the number of increments or decrements of the least significant digit DC Volts Measurement Range V dc Resolution Accuracy of Reading Counts 4 000 0 001 V 0 1 1 40 00 0 01 V 0 1 1 400 0 0 1 V 0 1 1 1000 1 V 0 1 1 Input impedance 10 MΩ nominal 100 pF Normal mode rejection ratio 60 dB at 50 Hz or 60 Hz Common mode rejection ratio 120 dB at dc 50 Hz or 60 Hz Overvoltage protect...

Page 48: ...V 0 1 mV 0 7 4 1 2 4 7 0 4 4 000 V 0 001 V 0 7 2 1 2 4 7 0 4 40 00 V 0 01 V 0 7 2 1 2 4 7 0 4 400 0 V 0 1 V 0 7 2 1 2 4 7 0 4 1000 V 1 V 0 7 2 1 2 4 7 0 4 Specifications are valid from 5 to 100 of amplitude range AC conversion true rms Maximum crest factor 3 between 50 and 60 Hz For non sinusoidal waveforms add 2 reading 2 f s typical Input impedance 10 MΩ nominal 100 pF ac coupled Common mode rej...

Page 49: ... 100 of amplitude range AC conversion true rms Maximum crest factor 3 between 50 and 60 Hz For non sinusoidal waveforms add 2 reading 2 f s typical Overload protection 440 mA 1000 V fast blow fuse DC Current Measurement Range Resolution Accuracy of Reading Counts Typical Burden Voltage 30 000 mA 0 001 mA 0 05 2 14 mV mA 1 000 A Note 0 001 A 0 2 2 1 5 V A Note 440 mA continuous 1 A 30 seconds maxim...

Page 50: ... Current Accuracy of Reading Counts 400 0 Ω 0 1 Ω 220 μA 0 2 2 4 000 kΩ 0 001 kΩ 60 μA 0 2 1 40 00 kΩ 0 01 kΩ 6 0 μA 0 2 1 400 0 kΩ 0 1 kΩ 600 nA 0 2 1 4 000 MΩ 0 001 MΩ 220 nA 0 35 3 40 00 MΩ 0 01 MΩ 22 nA 2 5 3 Overload protection 1000 V Open circuit voltage 3 9 V ...

Page 51: ...99 kHz 0 001 kHz 0 005 1 Display updates 3 times second at 10 Hz Frequency Counter Sensitivity Minimum Sensitivity rms Sinewave 5 Hz to 5 kHz Input Range AC DC approximate trigger level 5 of full scale 400 mV 150 mV 50 Hz to 5 kHz 150 mV 4 V 1 V 1 V 40 V 4 V 4 V 400 V 40 V 40 V 1000 V 400 V 400 V Usable 0 5 Hz to 20 kHz with reduced sensitivity 106 VHz max ...

Page 52: ...4 mA to 20 mA with overrange to 24 mA Accuracy 0 05 of span1 Compliance voltage 28 V with battery voltage 4 5 V Simulate Mode Span 0 mA or 4 mA to 20 mA with overrange to 24 mA Accuracy 0 05 of span1 Loop voltage 24 V nominal 48 V maximum 15 V minimum Compliance voltage 21 V for 24 V supply Burden voltage 3 V General Specifications Maximum voltage applied between any jack and earth ground 1000 V S...

Page 53: ... RF fields 3 V m Relative humidity 95 up to 30 C 75 up to 40 C 45 up to 50 C and 35 up to 55 C Vibration Random 2g 5 to 500 Hz Shock 1 meter drop test Safety The Meter complies with EN61010 1 2001 ANSI ISA S82 01 2004 CAN CSA C22 2 No 1010 1 2004 UL61010 1 Measurement Category III 1000V Pollution Degree 2 and Measurement Category IV 600V Pollution Degree 2 Certifications To 61010 1 2nd Edition Pow...

Page 54: ...789 Users Manual 46 ...

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