Fluke 787 Measuring Electrical Parameters, Input Impedance, Ranges, Measuring a Composite Signal

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ProcessMeter

Measuring Electrical Parameters

Measuring Electrical Parameters

The proper sequence for taking measurements is as follows:

1.Plug the test leads into the appropriate jacks.

2.Set the rotary knob.

3.Touch the probes to the test points.

The meter normally automatically selects the lowest range that will measure the applied input signal (Auto showing on the display). Press Kif you want to lock the range. Each time you press K, the meter selects the next higher range.

If you have locked the range, the meter resumes auto ranging when you change to another measurement function or you press Kand hold it for 1 second.

Input Impedance

For the voltage measurement functions, input impedance is 10 MΩ. See the specifications for more information.

Ranges

A measurement range determines the highest value the meter can measure. Most meter measurement functions have more than one range (see the Specifications).

Measuring a Composite Signal

Because the input is dc-coupled, to meaure an ac voltage or frequency with a dc bias, you must manually select the range specified in Table 7. For example, to measure 100 mV ac with 20 V dc superimposed, select the 4 V range.

Table 7. Range Requirements for Measuring a

Composite Signal

Being in the right range is important:

If the range is too low, the display shows OL (overload).

If the range is too high, the meter will not be displaying its most accurate measurement .

Range (ac)

400.0mV 4.000 V

40.00V

400.0V

1000 V

Max. Allowable AC + DC

3V 30 V

300V

400V

1000 V

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Contents 787 Limited Warranty & Limitation of Liability Table of Contents Index 787Read Safety Information before you use the meter IntroductionContacting Fluke 787 Safety InformationProcessMeter Symbol Meaning International Symbols MeaningFluke 787 ProcessMeter How to Get StartedInput/Output Jacks Getting Acquainted with the MeterInput/Output Jacks Measurement Functions Source Current FunctionSimulate Transmitter Function Rotary Switch Positions for Measurements Pushbutton Actions FunctionsRotary Switch Positions for mA Output Default Function Pushbuttons Functions PushbuttonsCoarse PushbuttonElements of the Display Display Meaning ElementDisplay Element MA, DC, mV, AC Or kΩ, kHz Auto 400100030 Measuring Electrical Parameters Measuring a Composite SignalInput Impedance RangesDisplaying Minimum, Maximum, and Average Testing DiodesCompensating for Test Lead Resistance Using TouchHoldSource Mode Using the Current Output FunctionsSourcing Current Changing the Current Span Simulate ModeSimulating a Transmitter MA Output Adjust Pushbuttons AdjustmentProducing a Steady mA Output MA Stepping Pushbuttons Manually Stepping the mA OutputAuto Ramping the mA Output MA Step Values Value for each span setting To 20 mAPower-Up Options Power-Up OptionsPushbutton Default Action TakenUsing the Holster and Flex-Stand Battery LifeMaintenance General MaintenanceUsing the Holster and Flex-Stand Replacing the Battery Replacing the BatteryReplacing a Fuse Replacing a Fuse If the Meter does not WorkReplacement Parts and Accessories Description Replacement PartsFluke PN or Model no QuantityMP8 Resolution SpecificationsDC Volts Measurement Range V dcRange mV dc Resolution 400.0 Accuracy % of Reading + Counts DC Millivolts MeasurementAC Volts Measurement DC Current Measurement AC Current MeasurementRange Resolution Ohms MeasurementMeasurement Current Frequency Counter Accuracy Frequency Counter SensitivityInput Range Minimum Sensitivity rms Sinewave 5 Hz to 5 kHz Source mode General SpecificationsSimulate Mode Diode Test and Continuity TestCertifications CSA, UL, TÜV Index Knob positions, 9 Pushbuttons Loop supply, external Index 787