Best Things You Must Know About Multimerers

Digital Multimeter | All The Best Things You Must Know About Multimeters

Analog multimeters were manufactured in the early twentieth century. The most common forms measured by this multimeter were d.c. and a.c. voltage, resistance, and d.c. current. These meters were known as volt-ohm-milliammeters or VOMs. After the commercial manufacturing of digital voltmeters in 1955, digital measurement and display technologies developed in parallel with digital integrated circuit technology until finally, in the late 1960s, portable digital versions of the VOM appeared. This form of multimeter has since been known as the digital multimeter.

Construction and Working

It shows the basic flow of information from the analog input signal through the various analog signal conversion circuits which convert the measured quantity to a d.c. voltage equivalent. Then the ADC translates this d.c. signal to digital form and the display system shows the resultant value with appropriate annunciation, such as measurement units of the original input signals. Thus, a digital multimeter is made up of the following three basic elements:

  •  signal conditioning
  • Analog-to-digital conversion (ADC)
  • Numeric digital display

A.C. or d.c. voltage, A.C. or d.c. current, and resistance are the most common parameters to be measured by a digital multimeter. Now digital multimeters are also being used to measure additional functions such as frequency, temperature, etc. To measure these parameters, first, these inputs must be switched and conditioned to present an equivalent d.c. voltage of the appropriate range to the analog-to-digital converter (ADC) or a sealed input to the counting circuits. The basic functioning of elements such as signal conditioning, ADC, and digital displays have already been explained in detail in Section 3.3 while describing digital voltmeter (DVM).

For d.c. voltage measurement by digital multimeter, a wide range of d.c. voltage inputs are scaled to the limited range of the ADC. A resistive divider and switching are generally used for this function.

For a.c. voltage measurement by digital multimeter, the signal is scaled and then converted to a d.c. equivalent value before sending it to the ADC. The methods of this conversion are already explained in Section 3.2 while describing analog electronic voltmeter (EVM).

For d.c. and a.c. current measurements by digital multimeter, it is necessary to convert the current at the input to a voltage for use by the ADC. This is done through a series of switched resistors, called shunts. A small-valued resistor through a series of switched resistors called shunts. A small-valued resistor in the input is placed in series with the current to be measured. Ohm’s law (V = IR) defines the small voltage proportional to the input current which is then measured. AC current measurement uses the same method except that the voltage across the shunt is routed through in a.c.-d.c. voltage converter before going to the ADC.

For resistance measurement, it is necessary to create a voltage proportional to the resistance because the ADC measures only d.c. volts. The digital multimeter input circuit must provide a d.c. current flowing through the resistor and then measure the resulting voltage. Many digital multimeters provide a calibrated constant current source for this purpose. Many others use reference resistors in series with the resistor being measured, and then measure the unknown and reference voltage drops. When combined with the known reference resistor values, this voltage-ratio technique also yields the desired resistance value.

Best Things You Must Know About Multimerers

What Constitutes A Good Multimeter

Advantages of Digital Multimeter (digital multimeter)

Following are the advantages of digital multimeters (digital multimeter):

  • digital multimeters offer high measurement accuracy.
  • These instruments have a high input impedance.
  • They are smaller in size.
  • These meters eliminate observational, parallax, and approximation errors.
  • The measured output of these instruments can be directly fed to a computer for further analysis and use.

digital multimeters can be evaluated on

  • a variety of features, such as accuracy, resolution, reading rates, and measurement ranges
  • additional functions, such as frequency, period, temperature, minimum/maximum, and diode test
  • math capabilities, such as relative, percent, or standard deviation readings.

Construction and Working

A basic block diagram of a virtual multimeter is shown in Fig.3.15. All digital multimeters and virtual multimeters share the same architecture. The architecture is divided into three main components namely, front-end signal conditioning. Analog-to-digital (A/D) converter, and processor, and display. Like traditional digital multimeters, virtual multimeters have front-end analog measurement circuitry to interface to real-world signals.

The A/D converter inside the virtual multimeter converts analog input signals to digital values. It is the primary component that affects reading speed, resolution, accuracy, and normal-mode rejection. Sophisticated virtual multimeters are multi-slope integrating A/D circuits or sigma-delta A/D converts to achieve high resolution and accuracy. A hardware A.C. conversion circuit is built on the dedicated multimeter boards in the signal-conditioning front end to convert A.C. signals to D.C. voltages to be measured by the A/D converter.

The A.C. converter may be either an averaging type or a True-rms (Trms) converter. Both averaging and Trms converters will give the same output for sine waves, but signals other than sine waves produce an error when measured with an average-based meter. For irregular waveforms, a Trms converter gives more accurate results. virtual multimeters built with general-purpose A/D boards, do not have specialized hardware A.C. conversion circuitry. Rather, they use software-specialized hardware A.C. conversion circuitry. Rather, they use software-based Trms A.C. conversion algorithms that execute on the computer itself.

virtual multimeters and digital multimeters offer a variety of measurement ranges. Common measurement ranges include 20 mV, 200mV, 2 V, 25 V, and 250 V front-end signal conditioning amplifiers and attenuators scale the input signal for a particular range setting. By scaling the input signal as close to the full range as possible, virtual multimeters/digital multimeters get the greatest resolution and accuracy.

Digital Fluke Multimeters

Fluke multimeters are known for their dependability and at Signal Test you can find a variety of digital Fluke multimeters designed to help handle your specific needs. From classic, general-purpose Fluke multimeters to those designed to help in the process of troubleshooting, Signal Test stocks the Fluke multimeters to help get the job done right. In addition to the many Fluke multimeters you can find at Signal Test, you can also find accessories to complement the Fluke multimeters we offer. From fuses to alligator clips you will find all of the accessories you need to customize our Fluke multimeters to your specifications.

More on Signal Test and Fluke Multimeters

From Fluke multimeters and Fluke instruments to HVAC supply, as an industrial supply leader, Signal Test sells the products every business and institution needs to keep its facilities and equipment up and running. We help customers get the job done by offering the broadest product selection in the industry. At Signal Test we understand that whether you are ordering Fluke multimeters or HVAC supplies, how important it is to get what you want when you want it.
Please take the time to visit our home page and browse through the Fluke multimeters and other quality products we sell.

Fluke 87 Multimeter — An Introduction

The Fluke 87 Multimeter is a versatile precision tool for use in the field, in laboratories, or in the home.  In this day and age, analog multimeters generally can’t compete with digital multimeters on cost and features. Consequently, most of the points made in this post assume the digital configuration. Basic multimeters measure voltage, resistance, and current. The Fluke 87 device also measures temperature, frequency, and amperage. Multimeters are often used to troubleshoot electronic problems by individually testing which components have stopped functioning or are functioning sub-optimally.

Fluke 87 Multimeter Applications

This state-of-the-art tool has a wide variety of applications that allows the electrician to test quickly and accurately unknown voltage levels and other vital information. The  Fluke 87-5  provides both auto and manual ranging for optimum flexibility. The Fluke 87 Multimeter is the world’s most popular industrial handheld digital multimeter. It is the standard against which all other digital multimeters are judged, and is known as reliable and dependable. It is an integral part of many industrial and commercial safety programs.

The Fluke Corporation started in 1948, is the world leader in the manufacture, distribution, and service of electronic test tools and software. The Fluke 87 Multimeter is one of their most popular instruments for measuring a wide range of electric and electromechanical performance variables.

Digital multimeters (DMMs) have made measuring the working condition of any electrical appliance or device very easy. Unlike, their analog counterpart, digital multimeters can be operated by anyone with a little guidance. And the display readings are in numbers, whereas analog multimeters indicate the value with a needle over a scale.

The Fluke 87 True RMS Digital Multimeter is a “must-have” tool for many. Its features ensure maximum safety and efficiency. This unit can perform precise voltage, resistance, amperage, and frequency measurements on virtually any electrical appliance, installation, or line voltage up to 1000 Volts and spike voltage up to 8000 Volts.

The Fluke 87 Multimeter has improved testing functions, trouble-shooting characteristics, resolution, and precision to diagnose and resolve performance issues on motor drives, in plant automation, power distribution, and various electronics equipment. The Fluke 87 sets a new benchmark for digital multimeters, delivering accuracy, many features, ease-of-use, safety, extreme durability, and reliability. It is extremely well-designed and built to last, with a brilliant record for durability and reliability. It has a large digit display with a bright two-level backlight.

Most digital multimeters are accurate to 1% for DC ranges and 2% for AC ranges. The highly advanced Fluke 87-5 is accurate to .05% DC. By way of comparison, analogue multimeters are generally accurate only up to 2.5% or higher. True-RMS AC voltage and current provide accurate measurements on non-linear signals. True RMS responding multimeters like the Fluke 87 Multimeter Series 5 measure the “heating” potential of an applied voltage.  Unlike an “average responding” measurement, a True RMS measurement is used to determine the power dissipated in a resistor.  The dissipated power is exactly proportional to the square of the measured True RMS voltage, independent of the wave shape, This is critical for precise testing on non-linear signals. On the 87-5, a selectable filter also ensures accurate voltage. An input alert sounds like an audible warning against the incorrect use of the input jacks. The Fluke 87 Multimeter is a very capable tool, well suited to industrial and commercial use, though also perfect for use at home.

People who perform installation, repair, and maintenance work on appliances, commercial washers, and dryers, inverters, transformers, furnaces, heaters, air conditioners, etc., require safe working conditions. A substantial number of serious accidents occur when the worker does not know with certainty when the electricity is off. An easy and safe way to make sure the electricity is off is to use the Fluke 87 Multimeter.

The Fluke 87 Multimeter is a versatile True-RMS meter that’s perfect for professional or around-the-house use. This meter offers auto- and manual-ranging for maximum flexibility, and it also offers an annual bar graph for quick-changing or unstable signals. The Fluke 87-5 has a removable holster with a built-in probe and test-lead storage. For added convenience, it arrives ready to go with TL75 test leads and a nine-volt battery, which generally provides up to 400 hours of use. Battery replacement does not cause loss of stored information. It comes with a soft case for storage when not in use.

The Fluke 87 Multimeter is probably the best multimeter in its price range. And the most expensive models can cost well over $500. This Series-5 digital multimeters (including the 87-8/E, 83-5, and 87 -5) have superior troubleshooting characteristics, measurement functions, power distribution, resolution, and accuracy to troubleshoot more complications in electronics, electro-mechanical accessories and equipment, and plant automation devices. The Series 5 multimeters are similar to the classic Series-3, but with substantially more convenience, problem-solving power, impact protection, and safety. The Series 5 comes with a lifetime warranty.

Fluke 87 Multimeter – Some features:

The Fluke 87 Multimeter’s ideal operating temperature range is from -4 to +130 degrees Fahrenheit, although it can be safely stored from -40 to +160 degrees. While it functions in humidity up to 90 percent, it should be stored in  70 percent humidity or less.

The Fluke 87 measures 1.25 x 3.41 x 7.35 inches and weighs 12.5 oz. The multimeter comes with a holster that also acts as a stand for the Fluke 87. This holster increases the size of the tool to 2.06 x 3.86 x 7.93 inches and the weight to 22 oz.

The Fluke 87 Multimeter measures a maximum of 1000 volts for both AC and DC. The maximum resolution when measuring voltage is .1 millivolts. The accuracy is +/- .05 percent for DC readings and +/-.7 percent for AC readings.

The Fluke 87 has a range of 1 nanofarad to 5 microfarads for capacitance readings and .5 Hertz to 200 kiloHertz for frequency readings.

The Fluke 87 Multimeter measures a maximum of 40 megawatts of resistance with an accuracy of plus or minus .2 percent. The maximum resolution for resistance readings is .1 watts.

The Fluke 87 Digital Multimeter measures a maximum current of 10 amps for both AC and DC. The maximum resolution when measuring current is .1 microamps. The accuracy is plus or minus .2 percent for DC readings and plus or minus 1. percent for AC readings.

The Fluke 87 Multimeter is often considered one of the best multimeters in the industry.  Fluke is a company that has been making electronic measurement devices since 1948. Fluke products are well known for their high-quality construction and many useful features.

A built-in thermometer lets you carry one less tool.

Other relevant features include auto and manual ranging, built-in thermometer, optional magnetic holder, and removable holster with built-in probe and test-lead storage. The Fluke 87 Multimeter can withstand dangerous and unpredictable volt spikes up to 8000 V caused by load switching and faults on industrial circuits.

Fluke 87 Multimeter: History of The Digital Meter

Multimeters were invented in the early 1920s as radio receivers and other vacuum tube electronic devices became more common. The invention of the first multimeter is attributed to British Post Office engineer, Donald Macadie who became dissatisfied with having to carry many separate instruments required for the maintenance of the telecommunications circuits. Macadie invented an instrument that could measure amperes (amps), volts and ohms so the multifunctional meter was then named Avometer. The meter comprised a moving coil meter, voltage and precision resistors, and switches and sockets to select the range.

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