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Fluke 8808A Digital Multimeter

Model: 8808 | UPC: 095969340137

Fluke 8808A Digital Multimeter-


Downloads: datasheet manual

Fluke 8808A Digital Multimeter

Model: 8808

5.5 digit multimeter, .01 %; Dual display.

5.5 digit multimeter, .01 %; Dual display.

This product has been discontinued. Click here for the replacement model(s).


Fluke 8808A Offers

Features

  • Dual display
  • Dedicated dc leakage current measurement
  • 2x4 ohms 4-wire measurement technique
  • Six dedicated buttons for fast access to instrument setups
  • Hi/Lo limit compare for Pass/Fail testing

Fluke 8808 Specifications

Technical Specifications
Display

VFD multi segment display, dual readings
Resolution

5.5 digits
V dc
Ranges 200 mV to 1000 V
Max. resolution 1 uV
Accuracy 0.015 + 0.003
V ac
Ranges 200 mV to 750 V
Max resolution 1 uV
Accuracy 0.2 + 0.05
Frequency 20 Hz to 100 KHz
Resistance
2x4 Wire Yes
Ranges 200 Ω to 100 MΩ
Max resolution 1 mΩ
Accuracy 0.02 + 0.003
A dc
Ranges 200 µA to 10 A
Max resolution 1 nA
Accuracy 0.02 + 0.005
A ac
Ranges 20 mA to 10 A
Max resolution 100 uA
Accuracy 0.3 + 0.06
Frequency 20 Hz to 2 kHz
Frequency
Ranges 20 Hz to 1 MHz
Max resolution 0.1 mHz
Accuracy 0.01 %
Math Functions
dB/dBm Yes
Advanced Functions

Limit compare test, with pass and fail indicators
Interfaces

RS-232, USB with optional adapter
Programming Languages/Modes

Simplified ASCII, Fluke 45 remote command emulation
General Specifications
Weight

2.1 kg (4.6 lbs)
Size (HxWxD)

88 mm x 217 mm x 297 mm (3.46 in x 8.56 in x 11.7 in)
Safety

Designed to comply with EN 61010-1:2001, ANSI/ISA 61010-1 (S82.02.01):2004, UL 61010-1:2004, AN/CSA C22.2 No. 61010.1:2004
Warranty

One year
Click here for complete specifications on the Fluke 8808

What's included with the Fluke 8808


  • Meter
  • TL71 test leads
  • Line cord
  • Spare line fuse
  • Statement of cal practices
  • WEEE information sheet
  • Warranty statement
  • Getting Started guide (English, French, German, Spanish, Italian, Simplified Chinese, Japanese)
  • CD Rom with user manual (English)

Multimeter measurements on adjustable speed drives

In the past, motor repair meant dealing with traditional three-phase motor failures that were largely the result of water, dust, grease, failed bearings, misaligned motor shafts, or just plain old age. But motor repair has changed in a big way with the introduction of electronically controlled motors, more commonly referred to as adjustable speed drives (ASDs). These drives present a unique set of measurement problems that can vex the most seasoned pro. Thanks to new technology, now for the first time you can take accurate electrical measurements with a DMM during the installation and maintenance of a drive and diagnose bad components and other conditions that may lead to premature failure.

Troubleshooting philosophy

Technicians use many different methods to troubleshoot an electrical circuit, and a good troubleshooter will always find the problem - eventually. The trick is tracking it down quickly and keeping downtime to a minimum. The most efficient troubleshooting procedure begins at the motor and then works systematically back to the electrical source, looking for the most obvious problems first. A lot of time and money can be wasted replacing perfectly good parts when the problem is simply a loose connection. As you go, take care to take accurate measurements. Nobody takes inaccurate measurements on purpose, but it's easy to do, especially when working in a high energy, noisy environment like an ASD. Likewise, choosing the right test tools for troubleshooting the drive, the motor, and the connections is of utmost importance. This is especially true when taking voltage, frequency and current measurements on the output side of the motor drive. But until now, there hasn't been a digital multimeter on the market able to accurately measure ASDs. Incorporates a selectable low pass filter* that allows for accurate drive output measurements that agree with the motor drive controller display indicator. Now, technicians won't have to guess whether the drive is operating correctly and delivering the correct voltage, current or frequency for a given control setting.

Drive measurements

Input side measurements

Any good quality True RMS multimeter can verify proper input power to an ASD. The input voltage readings should be within 1% of one another when measured phase to phase with no load. A significant unbalance may lead to erratic drive operation and should be corrected when discovered.

Output side measurements

On the flip side, a regular True RMS multimeter can't reliably read the output side of a pulse width modulated (pwm) motor drive, because the ASD applies pulse width modulated nonsinusoidal voltage to the motor terminals. A True RMS DMM reads the heating effect of the non-sinusoidal voltage applied to the motor, while the motor controller's output voltage reading only displays the rms value of the fundamental component (typically from 30 Hz to 60 Hz). The causes of this discrepancy are bandwidth and shielding. Many of today's True RMS digital multimeters have bandwidths out to 20 kHz or more, causing them to respond not only to the fundamental component, which is what the motor really responds to, but to all of the high frequency components generated by the pwm drive. And if the DMM isn't shielded for high frequency noise, the drive controller's high noise levels make the measurement discrepancies even more extreme. With the bandwidth and shielding issues combined, many True RMS meters display readings as much as 20 to 30% higher than what the drive controller is indicating. With the incorporated selectable low pass filter, allows troubleshooters to take accurate voltage, current and frequency measurements on the output side of the drive at either the drive itself or the motor terminals. With the filter selected, the readings for both voltage and frequency (motor speed) should agree with the associated drive control display indications, if available. The low pass filter also allows for accurate current measurements when used with Hall-effect type clamps. All of these measurements are especially helpful when taking measurements at the motor location when the drive's displays are not in view.

Taking safe measurements

Before taking any electrical measurements, be sure you understand how to take them safely. No test instrument is completely safe if used improperly, and many test instruments are not appropriate for testing adjustable speed drives. Also make sure to use the appropriate personal protective equipment (PPE) for your specific working environment and measurements. If at all possible, never work alone.

Safety ratings for electrical test equipment

ANSI and the International Electrotechnical Commission (IEC) are the primary independent organizations that define safety standards for test equipment manufacturers. The IEC 61010 second edition standard for test equipment safety states two basic parameters: a voltage rating and a measurement category rating. The voltage rating is the maximum continuous working voltage the instrument is capable of measuring. The category ratings depict the measurement environment expected for a given category. Most three-phase ASD installations would be considered a CAT III measurement environment, with power supplied from either 480V or 600V distribution systems. When using a DMM for measurements on these high energy systems, make sure it's rated at a minimum for CAT III 600V and preferably for CAT IV 600V/CAT III 1000V. The category rating and voltage limit are typically found on the front panel, at the input terminals. Dual-rated CAT IV 600V and CAT III 1000V. Refer to the ABC's of DMM Safety* from Fluke for additional information on category ratings and taking safe measurements.

How to take measurements

Now let's put the multimeter to the test. The measurements in the following procedure are designed to be made on a 480 volt 3 phase drive control at the control panel terminal strips. These procedures would also be valid for lower voltage 3 phase drives powered by either single or 3 phase supply voltages. For these tests the motor is running at 50 Hz.

Input voltage

To measure the ac voltage supply to the input side of the drive at the drive:

  • Select the ac voltage function.
  • Connect the black probe to one of the three phase input terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase input terminals and record the reading.
  • Leaving the black probe on the reference phase now move the red probe to the third phase input and record this reading.
  • Make sure there's no more than a 1% difference between these two readings.

Input current

Measuring the input current generally requires a current clamp accessory. In most cases, either the input current exceeds the maximum current measurable by the current function, or it isn't practical to "break the circuit" to take an in-line series current measurement. Regardless of clamp type, insure that all readings are within 10% of each other for proper balance.

Transformer type clamp (i200, 80i-400, 80i-600A)

  • Connect the clamp to the common and 400 mA input jacks.
  • Select the mA/A AC function.
  • Place the clamp around each of the input supply phase cables in succession, recording each of the readings as they are taken. Since these clamps output one milliamp per amp, the milliamp readings shown on the display are the actual phase current readings in amps.

Hall Effect type (AC/DC) clamp (i410,i-1010)

  • Connect the clamp to the common and V/W input jacks.
  • Select the AC voltage function.
  • Press the yellow button to enable the low pass filter. This allows the meter to reject all of the high frequency noise generated by the drive controller. Once the low pass filter is enabled, the meter will be in the 600 mV manual range mode.
  • Place the clamp around each of the input supply phase cables in succession, recording each of the readings as they are taken. Since these clamps output one millivolt per amp, the millivolt readings shown on the display are the actual phase current readings in amps.

Figure 1. Output voltage reading without using the low pass filter.


Figure 2. Output voltage reading with low pass filter enabled.

Output voltage

To measure the AC output voltage at either the drive or the motor terminals:

  • Plug the black test lead into the common jack and the red test lead into the V/W jack.
  • Select the AC voltage function.
  • Connect the black probe to one of the three phase output voltage or motor terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase output voltage or motor terminals.
  • Press the yellow button to enable the low pass filter. Now record the reading.
  • Leaving the black probe on the reference phase, now move the red probe to the third phase output voltage or motor terminal and record this reading.
  • Make sure that there's no more than a 1% difference between these two readings (see Figure 2). The readings should also agree with the controller display, panel if available.
  • If the low pass filter isn't enabled, the output voltage readings may be 10 to 30% higher, as on a regular DMM (see Figure 1).

Figure 3. Output frequency (motor speed) without the low pass filter.


Figure 4. Output frequency (motor speed) using the low pass filter.

Motor speed (Output frequency using voltage as a reference)

To determine motor speed, simply take a frequency measurement while using the low pass filter. The measurement can be made between any two of the phase voltage or motor terminals.

  • Plug the black test lead into the common jack and the red test lead into the V/W jack.
  • Select the ac voltage function.
  • Connect the black probe to one of the three phase output voltage or motor terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase output voltage or motor terminals.
  • Press the yellow button to enable the low pass filter.
  • Press the Hz button. The displayed reading in hertz will be the motor speed (see Figure 3). This measurement couldn't be made successfully without the low pass filter (see Figure 4).

Output current

TAs with input current, measuring the output current generally requires a current clamp accessory. Once again, regardless of clamp type, insure that all readings are within 10% of each other for proper balance.

Transformer type clamp (i200, 80i-400, 80i-600A)

  • Connect the clamp to the common and 400 mA input jacks.
  • Select the mA/A ac function.
  • Place the clamp around each of the output phase cables in succession, recording each of the readings as they're taken. Since these clamps output 1 milliamp per amp, the milliamp readings shown on the display are the actual phase current readings in amps.

Figure 5. Output current reading without using the low pass filter.


Figure 6. Output current reading with low pass filter enabled.

Hall Effect type (AC/DC) clamp (i410,i-1010)

  • Connect the clamp to the common and V/W input jacks.
  • Select the ac voltage function.
  • Press the yellow button to enable the low pass filter. This allows the meter to reject all of the high frequency noise generated by the drive controller. Once the low pass filter is turned on, the meter will be in the 600 mV manual range mode.
  • Place the clamp around each of the output phase cables in succession, recording each of the readings as they are taken (see Figure 6). Since these clamps output 1 millivolt per amp, the millivolt readings shown on the 87-V display are the actual phase current readings in amps. This measurement would not be possible without the low pass filter (see Figure 5).

Motor speed (Output frequency using current as a reference)

For motors that pull at least 20 amps of running current, motor speed can be determined by taking a frequency measurement with current clamps. Until now, noise issues have prevented accurate readings using hall effect type clamps. Here's how the low pass filter makes it possible.

Motor speed using a Hall Effect type (AC/DC) clamp (i410,i-1010)

  • Connect the clamp to the common and V/W input jacks.
  • Select the ac voltage function.
  • Press the yellow button to enable the low pass filter. This allows the meter to reject all of the high frequency noise generated by the drive controller. Once the low pass filter has been turned on, the meter will be in the 600 mV manual range mode.
  • Place the clamp around one of the output phase cables. Verify that the multimeter is reading a current of at least 20 amps (20 mV in the display).
  • Press the Hz button. The readings now display the motor speed as a frequency measurement.

Motor speed using a transformer type clamp (i200, 80i-400, 80i-600A)

  • Connect the clamp to the common and 400 mA input jacks.
  • Select the mA/A AC function.
  • Place the clamp around one of the output phase cables. Verify that the multimeter is reading a current of at least 20 amps (20mA in the display).
  • Press the Hz button. The readings now display the motor speed as a frequency measurement.

DC Bus measurements

A healthy dc bus is a must for a properly operating motor drive. If the bus voltage is incorrect or unstable, the converter diodes or capacitors may be starting to fail. The DC bus voltage should be approximately 1.414 times the phase to phase input voltage. For a 480 volt input, the DC bus should be approximately 679 VDC. The DC bus is typically labeled as DC+, DC- or B+, Bon the drive terminal strip. To measure the DC bus voltage:

  • Select the dc voltage function.
  • Connect the black probe to either the DC- or B- terminal.
  • Connect the red probe to the DC+ or B+ terminal. The bus voltage should agree with the example mentioned above and be relatively stable. To check the amount of ac ripple on the bus, switch the 7V's function switch to the vac function. Some small drives don't allow external access to the DC bus measurement without disassembling the drive. If you can't access the DC bus, use the peak min max function on the multimeter to measure the dc bus voltage via the output voltage signal.
  • Plug the black test lead into the common jack and the red test lead into the V/½ jack.
  • Select the AC voltage function.
  • Connect the black probe to one of the three phase output voltage or motor terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase output voltage or motor terminals.
  • Press the MIN MAX button.
  • Press the (Peak min max) button.
  • The displayed reading in Peak min max will be the DC bus voltage.

Click on a category to view a selection of compatible accessories with the Fluke 8808A Digital Multimeter.

Fluke 80CK-M type K Male Mini-Connectors 80CK-M
Yellow connectors with isothermal screw terminal. Pack of 2.





Fluke 80PK-1 Bead Probe 80PK-1
A K type thermocouple ideal for general purpose applications.




Fluke 80PK-22 SureGrip™ Immersion Temperature Probe 80PK-22
Compatible with any temperature measuring instrument that accepts K type thermocouples and features a miniature connector input. Additionally, this immersion temperature probe is for use in liquid and gels, and can also be used as a general-purpose probe.




Fluke 80PK-24 SureGrip™ Air Temperature Probe 80PK-24
A K type thermocouple probe ideal for use in air and non-caustic gas measurements. Additionally, this air temperature probe features a bead protected by perforated baffle.




Fluke 80PK-25 SureGrip™ Piercing Temperature Probe 80PK-25
A K type thermocouple probe that is suitable for the food industry, liquids, and gel.




Fluke 80PK-26 SureGrip Tapered Temperature Probe 80PK-26
Features a tapered tip, making this tapered temperature probe ideal for use in air, non-caustic gas, and surface applications.




Fluke 80PK-27 SureGrip™ Industrial Surface Temperature Probe 80PK-27
Compatible with any temperature measuring instrument that accepts type K thermocouples features a miniature connector input and a cold reference junction compensation. Additionally, this industrial surface temperature probe is ideal for surfaces in rugged environments.




Fluke 80PK-3A Surface Temperature Probe 80PK-3A
Compatible with any temperature measuring instrument that accepts type K thermocouples and features a miniature connector input. Additionally, this surface temperature probe is ideal for measuring the temperature of flat or slightly convex surfaces, with an exposed junction to allow direct contact with the surface being measured.




Fluke 80PK-8 Pipe Clamp Temperature Probe 80PK-8
Uses Type-K thermocouple for fast temperature and superheat measurements of pipe surfaces. Designed to reliably measure the temperature of pipes ¼" (6 mm) to 1⅜" (35 mm) in diameter, at temperatures between -20 and 300°F (-29 and 149°C), while retaining a long service life.




Fluke 80PK-9 General Purpose Probe 80PK-9
Featuring a general purpose type-K thermocouple probe for surface, air and non-caustic gases. It has a measuring range of -40 to 260°C.




Fluke 80PK-EXT Extension Wire Kit 80PK-EXT
Extension kit for type K thermocouple wires. Includes 3m of thermocouple wire and a pair of male/female mini-connectors.




Fluke 80T-150U Universal Temperature Probe 80T-150UA
A self-contained temperature-to-voltage converter, this probe is designed to provide a direct temperature reading when it is connected to any high impedance DMM capable of 1 mV resolution, and at least a 300-count full-scale readout capability.




Fluke 80TK Thermocouple Module 80TK
Thermocouple converter that accepts the output of any K-type thermocouple and converts it to 1 mV per degree (Celsius or Fahrenheit).




Fluke TL220 Suregrip Industrial Test Lead Set TL220
Includes the Fluke AC220, Fluke TP220, and Fluke TL224.




Fluke TL223 SureGrip™ Electrical Test Lead Set TL223
Designed for your comfort so you can focus on taking accurate measurements, this handy all-in-one kit comes equipped with a SureGrip alligator clip set, slim-reach test probes (flat bladed), and SureGrip silicone test lead set.




Fluke TL238 SureGrip™ Test Lead Set for High Energy Environments TL238
Designed for high energy environments, this kit comes equipped with the TP238, TP280, and TL224.




Fluke TL71 Premium Right Angle Test Lead Set TL71
Comfort grip probes with flexible silicone-insulated, right-angle test leads. They are heat and cold resistant, with a safety rating of CAT II 1000 V, 10 A.




Fluke TL76 Test Lead Set TL76
Pair of red, black silicone test leads with right angle shrouded 0.16" (4 mm) banana plugs.




Fluke TL80A Basic Electronic Test Lead Set TL80A
1 meter long silicone test lead set, alligator clip and probe tip extender in a soft carrying case.




Fluke TL81A Deluxe Electronic Test Lead Set TL81A
Works with Digital Multimeters that accept safety shrouded, standard diameter, banana connectors. Includes a quad-fold nylon pouch.




Fluke TL910 Electronic Test Probe Set TL910
One pair (red, black) of leads with very small tips to access hard to reach electronic test points.




Fluke TL225 SureGrip™ Stray Voltage Adapter Test Lead Kit TL225
Designed to assure that the meter has a low input impedance that eliminates stray voltage. Additionally, this stray voltage adapter test lead kit is compatible with all modern meters with standard input spacing.




Fluke TLK291 Fused Test Probe Set TLK291
Compatible with a variety of Fluke multimeters and test leads, this fused test probe set provides firm and secure contact.








Fluke 80K-15 High Voltage Probe 80K-15
Designed to extend the voltage measuring capability of an AC/DC voltmeter to 15,000 V peak AC or DC Overvoltage Category I. The probe provides high accuracy when used with a voltmeter having 10 MΩ input impedance. Intended for low energy applications.




Fluke 80K-40 High Voltage Probe 80K-40
Designed to extend the voltage measuring capability of an AC/DC voltmeter to 40,000 V peak AC or DC Overvoltage Category I. The probe provides high accuracy when used with a voltmeter having 10 MΩ input impedance. Intended for low energy applications.




Fluke 80K-6 KV High Voltage Probe 80K-6
Designed to extend the voltage measuring capability of an AC/DC voltmeter to 6000 V peak AC or DC Overvoltage Category I. The probe provides high accuracy when used with a voltmeter having 10 MΩ input impedance. Intended for low energy applications.




Fluke TLK287 Electronics Master Test Lead Set TLK287
Comes equipped with precision electronic probes with multiple spring loads sharp tips that are designed to maximize contact with SMD test points. Additionally, this master test lead set also comes with modular test leads and lead-probe combinations ideal for long lead applications.








Fluke Y8846D Rack Mount Kit Y8846D
Mounting kit for the Fluke 8845A and 8846A. Includes everything you need to mount two meters on a 19in rack.




Fluke Y8846S Rack Mount Kit Y8846S
Mounting kit for the Fluke 8845A and 8846A. Includes everything you need to mount one meter on a 19in rack.




Fluke PV350 Pressure Vacuum Module PV350
Compatible with a variety of digital multimeters, this pressure vacuum module measures vacuum to 76 cm Hg and pressure to 3447 kPa (500 psig).




Fluke FVF-UG FlukeView Forms Software Upgrade FVF-UG
Software Upgrade to FlukeView Forms Version 3.0. Includes users manual, registration card, and software license agreement.




Fluke FlukeView Forms Software with cable (FVF-SC2) FVF-SC2
For use with the Fluke 180 Series, 789, 1550B, 1550C, 1555, 53-2-B, 54-2-B and 1653.




Customer Reviews for the Fluke 8808

Ask a question about Fluke 8808A Digital Multimeter

Fluke 8808A Offers

Features

  • Dual display
  • Dedicated dc leakage current measurement
  • 2x4 ohms 4-wire measurement technique
  • Six dedicated buttons for fast access to instrument setups
  • Hi/Lo limit compare for Pass/Fail testing

Fluke 8808 Specifications

Technical Specifications
Display

VFD multi segment display, dual readings
Resolution

5.5 digits
V dc
Ranges 200 mV to 1000 V
Max. resolution 1 uV
Accuracy 0.015 + 0.003
V ac
Ranges 200 mV to 750 V
Max resolution 1 uV
Accuracy 0.2 + 0.05
Frequency 20 Hz to 100 KHz
Resistance
2x4 Wire Yes
Ranges 200 Ω to 100 MΩ
Max resolution 1 mΩ
Accuracy 0.02 + 0.003
A dc
Ranges 200 µA to 10 A
Max resolution 1 nA
Accuracy 0.02 + 0.005
A ac
Ranges 20 mA to 10 A
Max resolution 100 uA
Accuracy 0.3 + 0.06
Frequency 20 Hz to 2 kHz
Frequency
Ranges 20 Hz to 1 MHz
Max resolution 0.1 mHz
Accuracy 0.01 %
Math Functions
dB/dBm Yes
Advanced Functions

Limit compare test, with pass and fail indicators
Interfaces

RS-232, USB with optional adapter
Programming Languages/Modes

Simplified ASCII, Fluke 45 remote command emulation
General Specifications
Weight

2.1 kg (4.6 lbs)
Size (HxWxD)

88 mm x 217 mm x 297 mm (3.46 in x 8.56 in x 11.7 in)
Safety

Designed to comply with EN 61010-1:2001, ANSI/ISA 61010-1 (S82.02.01):2004, UL 61010-1:2004, AN/CSA C22.2 No. 61010.1:2004
Warranty

One year
Click here for complete specifications on the Fluke 8808

What's included with the Fluke 8808


  • Meter
  • TL71 test leads
  • Line cord
  • Spare line fuse
  • Statement of cal practices
  • WEEE information sheet
  • Warranty statement
  • Getting Started guide (English, French, German, Spanish, Italian, Simplified Chinese, Japanese)
  • CD Rom with user manual (English)

Multimeter measurements on adjustable speed drives

In the past, motor repair meant dealing with traditional three-phase motor failures that were largely the result of water, dust, grease, failed bearings, misaligned motor shafts, or just plain old age. But motor repair has changed in a big way with the introduction of electronically controlled motors, more commonly referred to as adjustable speed drives (ASDs). These drives present a unique set of measurement problems that can vex the most seasoned pro. Thanks to new technology, now for the first time you can take accurate electrical measurements with a DMM during the installation and maintenance of a drive and diagnose bad components and other conditions that may lead to premature failure.

Troubleshooting philosophy

Technicians use many different methods to troubleshoot an electrical circuit, and a good troubleshooter will always find the problem - eventually. The trick is tracking it down quickly and keeping downtime to a minimum. The most efficient troubleshooting procedure begins at the motor and then works systematically back to the electrical source, looking for the most obvious problems first. A lot of time and money can be wasted replacing perfectly good parts when the problem is simply a loose connection. As you go, take care to take accurate measurements. Nobody takes inaccurate measurements on purpose, but it's easy to do, especially when working in a high energy, noisy environment like an ASD. Likewise, choosing the right test tools for troubleshooting the drive, the motor, and the connections is of utmost importance. This is especially true when taking voltage, frequency and current measurements on the output side of the motor drive. But until now, there hasn't been a digital multimeter on the market able to accurately measure ASDs. Incorporates a selectable low pass filter* that allows for accurate drive output measurements that agree with the motor drive controller display indicator. Now, technicians won't have to guess whether the drive is operating correctly and delivering the correct voltage, current or frequency for a given control setting.

Drive measurements

Input side measurements

Any good quality True RMS multimeter can verify proper input power to an ASD. The input voltage readings should be within 1% of one another when measured phase to phase with no load. A significant unbalance may lead to erratic drive operation and should be corrected when discovered.

Output side measurements

On the flip side, a regular True RMS multimeter can't reliably read the output side of a pulse width modulated (pwm) motor drive, because the ASD applies pulse width modulated nonsinusoidal voltage to the motor terminals. A True RMS DMM reads the heating effect of the non-sinusoidal voltage applied to the motor, while the motor controller's output voltage reading only displays the rms value of the fundamental component (typically from 30 Hz to 60 Hz). The causes of this discrepancy are bandwidth and shielding. Many of today's True RMS digital multimeters have bandwidths out to 20 kHz or more, causing them to respond not only to the fundamental component, which is what the motor really responds to, but to all of the high frequency components generated by the pwm drive. And if the DMM isn't shielded for high frequency noise, the drive controller's high noise levels make the measurement discrepancies even more extreme. With the bandwidth and shielding issues combined, many True RMS meters display readings as much as 20 to 30% higher than what the drive controller is indicating. With the incorporated selectable low pass filter, allows troubleshooters to take accurate voltage, current and frequency measurements on the output side of the drive at either the drive itself or the motor terminals. With the filter selected, the readings for both voltage and frequency (motor speed) should agree with the associated drive control display indications, if available. The low pass filter also allows for accurate current measurements when used with Hall-effect type clamps. All of these measurements are especially helpful when taking measurements at the motor location when the drive's displays are not in view.

Taking safe measurements

Before taking any electrical measurements, be sure you understand how to take them safely. No test instrument is completely safe if used improperly, and many test instruments are not appropriate for testing adjustable speed drives. Also make sure to use the appropriate personal protective equipment (PPE) for your specific working environment and measurements. If at all possible, never work alone.

Safety ratings for electrical test equipment

ANSI and the International Electrotechnical Commission (IEC) are the primary independent organizations that define safety standards for test equipment manufacturers. The IEC 61010 second edition standard for test equipment safety states two basic parameters: a voltage rating and a measurement category rating. The voltage rating is the maximum continuous working voltage the instrument is capable of measuring. The category ratings depict the measurement environment expected for a given category. Most three-phase ASD installations would be considered a CAT III measurement environment, with power supplied from either 480V or 600V distribution systems. When using a DMM for measurements on these high energy systems, make sure it's rated at a minimum for CAT III 600V and preferably for CAT IV 600V/CAT III 1000V. The category rating and voltage limit are typically found on the front panel, at the input terminals. Dual-rated CAT IV 600V and CAT III 1000V. Refer to the ABC's of DMM Safety* from Fluke for additional information on category ratings and taking safe measurements.

How to take measurements

Now let's put the multimeter to the test. The measurements in the following procedure are designed to be made on a 480 volt 3 phase drive control at the control panel terminal strips. These procedures would also be valid for lower voltage 3 phase drives powered by either single or 3 phase supply voltages. For these tests the motor is running at 50 Hz.

Input voltage

To measure the ac voltage supply to the input side of the drive at the drive:

  • Select the ac voltage function.
  • Connect the black probe to one of the three phase input terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase input terminals and record the reading.
  • Leaving the black probe on the reference phase now move the red probe to the third phase input and record this reading.
  • Make sure there's no more than a 1% difference between these two readings.

Input current

Measuring the input current generally requires a current clamp accessory. In most cases, either the input current exceeds the maximum current measurable by the current function, or it isn't practical to "break the circuit" to take an in-line series current measurement. Regardless of clamp type, insure that all readings are within 10% of each other for proper balance.

Transformer type clamp (i200, 80i-400, 80i-600A)

  • Connect the clamp to the common and 400 mA input jacks.
  • Select the mA/A AC function.
  • Place the clamp around each of the input supply phase cables in succession, recording each of the readings as they are taken. Since these clamps output one milliamp per amp, the milliamp readings shown on the display are the actual phase current readings in amps.

Hall Effect type (AC/DC) clamp (i410,i-1010)

  • Connect the clamp to the common and V/W input jacks.
  • Select the AC voltage function.
  • Press the yellow button to enable the low pass filter. This allows the meter to reject all of the high frequency noise generated by the drive controller. Once the low pass filter is enabled, the meter will be in the 600 mV manual range mode.
  • Place the clamp around each of the input supply phase cables in succession, recording each of the readings as they are taken. Since these clamps output one millivolt per amp, the millivolt readings shown on the display are the actual phase current readings in amps.

Figure 1. Output voltage reading without using the low pass filter.


Figure 2. Output voltage reading with low pass filter enabled.

Output voltage

To measure the AC output voltage at either the drive or the motor terminals:

  • Plug the black test lead into the common jack and the red test lead into the V/W jack.
  • Select the AC voltage function.
  • Connect the black probe to one of the three phase output voltage or motor terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase output voltage or motor terminals.
  • Press the yellow button to enable the low pass filter. Now record the reading.
  • Leaving the black probe on the reference phase, now move the red probe to the third phase output voltage or motor terminal and record this reading.
  • Make sure that there's no more than a 1% difference between these two readings (see Figure 2). The readings should also agree with the controller display, panel if available.
  • If the low pass filter isn't enabled, the output voltage readings may be 10 to 30% higher, as on a regular DMM (see Figure 1).

Figure 3. Output frequency (motor speed) without the low pass filter.


Figure 4. Output frequency (motor speed) using the low pass filter.

Motor speed (Output frequency using voltage as a reference)

To determine motor speed, simply take a frequency measurement while using the low pass filter. The measurement can be made between any two of the phase voltage or motor terminals.

  • Plug the black test lead into the common jack and the red test lead into the V/W jack.
  • Select the ac voltage function.
  • Connect the black probe to one of the three phase output voltage or motor terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase output voltage or motor terminals.
  • Press the yellow button to enable the low pass filter.
  • Press the Hz button. The displayed reading in hertz will be the motor speed (see Figure 3). This measurement couldn't be made successfully without the low pass filter (see Figure 4).

Output current

TAs with input current, measuring the output current generally requires a current clamp accessory. Once again, regardless of clamp type, insure that all readings are within 10% of each other for proper balance.

Transformer type clamp (i200, 80i-400, 80i-600A)

  • Connect the clamp to the common and 400 mA input jacks.
  • Select the mA/A ac function.
  • Place the clamp around each of the output phase cables in succession, recording each of the readings as they're taken. Since these clamps output 1 milliamp per amp, the milliamp readings shown on the display are the actual phase current readings in amps.

Figure 5. Output current reading without using the low pass filter.


Figure 6. Output current reading with low pass filter enabled.

Hall Effect type (AC/DC) clamp (i410,i-1010)

  • Connect the clamp to the common and V/W input jacks.
  • Select the ac voltage function.
  • Press the yellow button to enable the low pass filter. This allows the meter to reject all of the high frequency noise generated by the drive controller. Once the low pass filter is turned on, the meter will be in the 600 mV manual range mode.
  • Place the clamp around each of the output phase cables in succession, recording each of the readings as they are taken (see Figure 6). Since these clamps output 1 millivolt per amp, the millivolt readings shown on the 87-V display are the actual phase current readings in amps. This measurement would not be possible without the low pass filter (see Figure 5).

Motor speed (Output frequency using current as a reference)

For motors that pull at least 20 amps of running current, motor speed can be determined by taking a frequency measurement with current clamps. Until now, noise issues have prevented accurate readings using hall effect type clamps. Here's how the low pass filter makes it possible.

Motor speed using a Hall Effect type (AC/DC) clamp (i410,i-1010)

  • Connect the clamp to the common and V/W input jacks.
  • Select the ac voltage function.
  • Press the yellow button to enable the low pass filter. This allows the meter to reject all of the high frequency noise generated by the drive controller. Once the low pass filter has been turned on, the meter will be in the 600 mV manual range mode.
  • Place the clamp around one of the output phase cables. Verify that the multimeter is reading a current of at least 20 amps (20 mV in the display).
  • Press the Hz button. The readings now display the motor speed as a frequency measurement.

Motor speed using a transformer type clamp (i200, 80i-400, 80i-600A)

  • Connect the clamp to the common and 400 mA input jacks.
  • Select the mA/A AC function.
  • Place the clamp around one of the output phase cables. Verify that the multimeter is reading a current of at least 20 amps (20mA in the display).
  • Press the Hz button. The readings now display the motor speed as a frequency measurement.

DC Bus measurements

A healthy dc bus is a must for a properly operating motor drive. If the bus voltage is incorrect or unstable, the converter diodes or capacitors may be starting to fail. The DC bus voltage should be approximately 1.414 times the phase to phase input voltage. For a 480 volt input, the DC bus should be approximately 679 VDC. The DC bus is typically labeled as DC+, DC- or B+, Bon the drive terminal strip. To measure the DC bus voltage:

  • Select the dc voltage function.
  • Connect the black probe to either the DC- or B- terminal.
  • Connect the red probe to the DC+ or B+ terminal. The bus voltage should agree with the example mentioned above and be relatively stable. To check the amount of ac ripple on the bus, switch the 7V's function switch to the vac function. Some small drives don't allow external access to the DC bus measurement without disassembling the drive. If you can't access the DC bus, use the peak min max function on the multimeter to measure the dc bus voltage via the output voltage signal.
  • Plug the black test lead into the common jack and the red test lead into the V/½ jack.
  • Select the AC voltage function.
  • Connect the black probe to one of the three phase output voltage or motor terminals. This will be the reference phase.
  • Connect the red probe to one of the other two phase output voltage or motor terminals.
  • Press the MIN MAX button.
  • Press the (Peak min max) button.
  • The displayed reading in Peak min max will be the DC bus voltage.

Click on a category to view a selection of compatible accessories with the Fluke 8808A Digital Multimeter.

Fluke 80CK-M type K Male Mini-Connectors 80CK-M
Yellow connectors with isothermal screw terminal. Pack of 2.





Fluke 80PK-1 Bead Probe 80PK-1
A K type thermocouple ideal for general purpose applications.




Fluke 80PK-22 SureGrip™ Immersion Temperature Probe 80PK-22
Compatible with any temperature measuring instrument that accepts K type thermocouples and features a miniature connector input. Additionally, this immersion temperature probe is for use in liquid and gels, and can also be used as a general-purpose probe.




Fluke 80PK-24 SureGrip™ Air Temperature Probe 80PK-24
A K type thermocouple probe ideal for use in air and non-caustic gas measurements. Additionally, this air temperature probe features a bead protected by perforated baffle.




Fluke 80PK-25 SureGrip™ Piercing Temperature Probe 80PK-25
A K type thermocouple probe that is suitable for the food industry, liquids, and gel.




Fluke 80PK-26 SureGrip Tapered Temperature Probe 80PK-26
Features a tapered tip, making this tapered temperature probe ideal for use in air, non-caustic gas, and surface applications.




Fluke 80PK-27 SureGrip™ Industrial Surface Temperature Probe 80PK-27
Compatible with any temperature measuring instrument that accepts type K thermocouples features a miniature connector input and a cold reference junction compensation. Additionally, this industrial surface temperature probe is ideal for surfaces in rugged environments.




Fluke 80PK-3A Surface Temperature Probe 80PK-3A
Compatible with any temperature measuring instrument that accepts type K thermocouples and features a miniature connector input. Additionally, this surface temperature probe is ideal for measuring the temperature of flat or slightly convex surfaces, with an exposed junction to allow direct contact with the surface being measured.




Fluke 80PK-8 Pipe Clamp Temperature Probe 80PK-8
Uses Type-K thermocouple for fast temperature and superheat measurements of pipe surfaces. Designed to reliably measure the temperature of pipes ¼" (6 mm) to 1⅜" (35 mm) in diameter, at temperatures between -20 and 300°F (-29 and 149°C), while retaining a long service life.




Fluke 80PK-9 General Purpose Probe 80PK-9
Featuring a general purpose type-K thermocouple probe for surface, air and non-caustic gases. It has a measuring range of -40 to 260°C.




Fluke 80PK-EXT Extension Wire Kit 80PK-EXT
Extension kit for type K thermocouple wires. Includes 3m of thermocouple wire and a pair of male/female mini-connectors.




Fluke 80T-150U Universal Temperature Probe 80T-150UA
A self-contained temperature-to-voltage converter, this probe is designed to provide a direct temperature reading when it is connected to any high impedance DMM capable of 1 mV resolution, and at least a 300-count full-scale readout capability.




Fluke 80TK Thermocouple Module 80TK
Thermocouple converter that accepts the output of any K-type thermocouple and converts it to 1 mV per degree (Celsius or Fahrenheit).




Fluke TL220 Suregrip Industrial Test Lead Set TL220
Includes the Fluke AC220, Fluke TP220, and Fluke TL224.




Fluke TL223 SureGrip™ Electrical Test Lead Set TL223
Designed for your comfort so you can focus on taking accurate measurements, this handy all-in-one kit comes equipped with a SureGrip alligator clip set, slim-reach test probes (flat bladed), and SureGrip silicone test lead set.




Fluke TL238 SureGrip™ Test Lead Set for High Energy Environments TL238
Designed for high energy environments, this kit comes equipped with the TP238, TP280, and TL224.




Fluke TL71 Premium Right Angle Test Lead Set TL71
Comfort grip probes with flexible silicone-insulated, right-angle test leads. They are heat and cold resistant, with a safety rating of CAT II 1000 V, 10 A.




Fluke TL76 Test Lead Set TL76
Pair of red, black silicone test leads with right angle shrouded 0.16" (4 mm) banana plugs.




Fluke TL80A Basic Electronic Test Lead Set TL80A
1 meter long silicone test lead set, alligator clip and probe tip extender in a soft carrying case.




Fluke TL81A Deluxe Electronic Test Lead Set TL81A
Works with Digital Multimeters that accept safety shrouded, standard diameter, banana connectors. Includes a quad-fold nylon pouch.




Fluke TL910 Electronic Test Probe Set TL910
One pair (red, black) of leads with very small tips to access hard to reach electronic test points.




Fluke TL225 SureGrip™ Stray Voltage Adapter Test Lead Kit TL225
Designed to assure that the meter has a low input impedance that eliminates stray voltage. Additionally, this stray voltage adapter test lead kit is compatible with all modern meters with standard input spacing.




Fluke TLK291 Fused Test Probe Set TLK291
Compatible with a variety of Fluke multimeters and test leads, this fused test probe set provides firm and secure contact.








Fluke 80K-15 High Voltage Probe 80K-15
Designed to extend the voltage measuring capability of an AC/DC voltmeter to 15,000 V peak AC or DC Overvoltage Category I. The probe provides high accuracy when used with a voltmeter having 10 MΩ input impedance. Intended for low energy applications.




Fluke 80K-40 High Voltage Probe 80K-40
Designed to extend the voltage measuring capability of an AC/DC voltmeter to 40,000 V peak AC or DC Overvoltage Category I. The probe provides high accuracy when used with a voltmeter having 10 MΩ input impedance. Intended for low energy applications.




Fluke 80K-6 KV High Voltage Probe 80K-6
Designed to extend the voltage measuring capability of an AC/DC voltmeter to 6000 V peak AC or DC Overvoltage Category I. The probe provides high accuracy when used with a voltmeter having 10 MΩ input impedance. Intended for low energy applications.




Fluke TLK287 Electronics Master Test Lead Set TLK287
Comes equipped with precision electronic probes with multiple spring loads sharp tips that are designed to maximize contact with SMD test points. Additionally, this master test lead set also comes with modular test leads and lead-probe combinations ideal for long lead applications.








Fluke Y8846D Rack Mount Kit Y8846D
Mounting kit for the Fluke 8845A and 8846A. Includes everything you need to mount two meters on a 19in rack.




Fluke Y8846S Rack Mount Kit Y8846S
Mounting kit for the Fluke 8845A and 8846A. Includes everything you need to mount one meter on a 19in rack.




Fluke PV350 Pressure Vacuum Module PV350
Compatible with a variety of digital multimeters, this pressure vacuum module measures vacuum to 76 cm Hg and pressure to 3447 kPa (500 psig).




Fluke FVF-UG FlukeView Forms Software Upgrade FVF-UG
Software Upgrade to FlukeView Forms Version 3.0. Includes users manual, registration card, and software license agreement.




Fluke FlukeView Forms Software with cable (FVF-SC2) FVF-SC2
For use with the Fluke 180 Series, 789, 1550B, 1550C, 1555, 53-2-B, 54-2-B and 1653.




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