How to Use Multimeter ?
How to Use Multimeter ?
A multimeter is a very useful instrument for an electrician. Every now and then electrical personnel need it for profession. A trained electrician or an educated Electrical Engineer isn’t the lone user of a multimeter. For household purposes one can use it; an electronics hobbyist may also use it for his purposes and so on.
Let’s talk about the analog multimeter first. An analog multimeter has a graduated dial on which a pointer moves to indicate the measured value of the variable. Well, the variables are voltage, current and resistance which are measured with this meter. You have to select the variable on the meter before making any measurement.
A rotary selector switch is there below the dial to make the selection. You can see different positions of the selector switch with markings of Voltage (AC/DC), Ampere (AC/DC) and Ohms. Sorry man, I haven’t mentioned yet what is ampere and ohm. These are the measuring units for electrical current and resistance respectively.
Voltage (AC/DC) may have several ranges of measurement. Similar the case is for ampere. So before going to measure any of these parameters, it would be better if you have some idea about the value of the parameter which you are going to measure. If you have the idea, you should select a range well above the estimate.
We can have an example here. Our domestic electricity voltage is 110V or 240V. If you know it to be 110V, for measuring it you can select a range of 200V on the meter. But if you have any confusion, it’s wise to select a range higher than 240V.
The very first reading will help you to be confirmed of it. In case you find it to be close to 110V, you can now select the 200V range and you may get a more accurate measurement. Any higher range selection is not harmful for the instrument. But having selected a range lower than the measured value, may damage the instrument. If you select a much higher range, the instrument is safe but the measurement is less accurate.
Volt is the unit of potential difference between two points. So when you like to find out a voltage, you actually desire to find the potential difference between two points. Hence you have to make contact of the test leads with the two points of interest. Well, you have to push the other ends of the test leads into the correct sockets on the meter first. Take the two test leads on two hands and make contact with two target points with the tips of the leads. Take care not to touch the open tips with yourfingers. The two targets should be clean of dirt and foreign material. Otherwise you may not get a correct result.
For getting an accurate result in measurement you must view the pointer avoiding any parallax. You know what parallax is? Let me explain. Your eye must be perfect vertical with the dial when you look at the pointer. In any other angle you’ll add some error to the reading. Some manufacturers add a strip of mirror along the side of the scale that helps to get a parallax free view.
Measuring unit of electrical current is ampere. So ampere is a flow (of electrons). For measuring the flow the instrument must be placed in the path of flow. So you have to make a room for the meter to place in the flow path. The following diagrams would make it clear to you.
Fig.1 shows the circuit of which you like to measure the current. Fig.2 shows how to connect the meter in the circuit to get the same current passing through it. You have to keep in mind that before measuring a current you must select ampere (AC/DC) and the proper range on the multimeter. The meter is shown here to be placed after the switch and before the lamp. But it’s immaterial to place here or anywhere in the current path. This is termed as a series connection.
Resistance measurement is another vital function of a multimeter. If you want to measure the resistance value of a lamp you just take it out of the socket, set your meter at Ohm and touch the two terminals of it with the test leads of the meter. You get a result. If the value is very low in comparison with the range you may choose a lower range to get a more correct measurement. If you have to measure the resistance of a tiny resistive element on a printed circuit, you have to disconnect its at least one terminal from the circuit. Otherwise you won’t get the correct value.
The difference in making measurement with an analog meter and a digital one is very a little. It’s rather simple to measure with a digital meter. There is no chance of any parallax. Otherwise it’s all the same.
From the very name it’s clear that a multimeter is an instrument with several functions. A multimeter is used for measuring electrical parameters like voltage, current, ohm and some more. Once people used to call it an AVO meter from the first letters of the three major items of its concern.
For an electrician or an Electrical Engineer a multimeter is a very important tool. To start working regarding a new installation or maintenance an electrician has to be sanguine about the line voltage available. There is no way to confirm this without a meter. A voltmeter may serve the purpose. But in the next step he or she would require to measure a current flow. Then he will need an ampere meter also. At one time he would have to measure a circuit resistance. He will ask for an ohmmeter for that. So he would need three measuring instruments.
A multimeter would serve all the three purposes. It’s a compact, handy instrument and very much portable. Some brand products are so small; you can take it in your pocket even. However it’s such an instrument an electrician can’t think of an hour without it.
In addition to the measurement of above three parameters a multimeter is designed to test transistors.
Selecting Type and Range
As it’s manufactured to measure and test different items, it has got a selector switch to select for the desired one. A multimeter is designed to measure both A.C and D.C voltages. It has got different voltage ranges to choose. So for measuring a voltage you have to select the voltage type and range.
Similar the case is about measuring a resistance. You have to choose the range. Electrical current measurement is a bit tricky. The meter is to be connected in series for that. Otherwise you won’t get the measurement. Rather you would ruin the equipment.
Hence before measuring a voltage you must choose from A.C and D.C and at the same time you have to select a range. If you select a very high range your result will be less accurate. But you can change the range for accurate result. In case you select a range lower than actual, the meter may be damaged. So select the correct one or a higher one.
Before measuring a current flow you have to discontinue the circuit in which you like to measure the current and connect the meter in between to complete the circuit. If you connect the meter between two points having a potential difference, that will blow the safety fuse or even may damage the meter. So you should be very careful about it.
Resistance measurement is rather simple as you have to switch off the power or at least isolate the part of which you desire to measure the resistance. You may also detect continuity of a circuit with resistance measurement selected. This is a very useful thing for an electrician.
Some Words of Advice
Once multimeters were analog and a pointer moved to show the measured result. Now it’s digital and of course it’s much easier to read the value. A multimeter needs D.C. power for its functioning. Normally a battery is used for the purpose. As the battery gets discharged gradually it needs replacement. Replace the battery at proper time. Otherwise leakage of battery may damage the circuits of the meter itself.
Buy a good multimeter, use it properly, replace the battery at correct time and work safely.
Digital Multimeter Buying Guide
When you plan to purchase a Multimeter, there are a few things you need to take into consideration. Obtaining the proper information will allow you to have the correct knowledge to get the proper multimeter that you are paying for. Some examples of things you should know would be the cost, what brand would be your best option, how to use it, and what you should look for when purchasing one. Figuring out want you want and need in a multimeter before you buy one will make actually getting one much easier.
First of all, the pricing on a Multimeter varies on the brand and what features you want to go with it. You could spend anywhere between $50.00 and $450.00. If you buy one that is not calibrated you can get it cheaper, but to keep it at a factory’s accuracy you have to get it calibrated at least once a year and that’s going to cost you around $50.00 or so.
You will probably not find one that is calibrated under 100 dollars. If you can live without it and go with a cheaper model, that’s fine but you will have to replace it once it becomes inaccurate. Also you can have a hand held model, which would be the inexpensive route to go, or if you would prefer a bench top model, that could bring you up to a $1,000. Bench top multimeters tend to be extremely expensive.
Secondly, you will need to know a little bit about what the device has to offer. All digital multimeters have an LCD screen that will display a decimal readout. Digital variants tend to be alot more accurate by at least 5% compared to an analog. It lets you measure things like AC or DC voltage, resistance and current. Many of the more common features that come along with a digital multimeter would be dB ratings, auto ranging, Adjustable sample rating, Removable data storage, Triggering and Data Acquisitions. You can also get added features such as transistor test, Auto continuity and the capability of measuring temperature.
Also, there are many different ways that you can use it. The word multi implies that you can get more than one measurement. Some examples of what you can use your multimeter on, depending on the type of features your multimeter has, would be Batteries, motors, components, power sources and switches. To find out the complete list of what all you can use your multimeter on both indoors and out would be to check your service manual that you receive when you buy it.
On another note, you need to be sure to know if the unit you plan to buy has auto ranging. Having a multimeter with auto range gives you a device that is very flexible and allows you to be able to select a wide range of voltages. It works wonders on detecting computer malfunctions as well as wiring systems and so many more things.
Brands and Quality
Also, There are many different brands that you can choose from that provide high quality digital multimeters. Different brands carry different prices so you will have to shop and compare to find the proper multimeter that you need that in is the budget that you can afford. A few examples of brands of multimeters are Fluke, Aligent, Wavetek/Metermen, B+K Precision, Beckman and HP and Extech. These are all very reputable brands of multimeters. They provide you with high quality products that offer you the best possible results. It is advised for you to research each brand and they’re manufactures before hand to gain a better knowledge base, as well as look at some reviews from previous customers of theirs. There are many other multimeter brands available out there as well.
In summary, There are many different options out there available to you, with a little bit of research and a set budget before you jump in to buy, will save you major amounts of money. With a digital multimeter you will be able to do some of the handy work yourself, which in return will save you money by not having to get a electrician, technician or mechanic coming in and doing it for you.
The Fluke 1587 works as a regular – although high-end – true-RMS multimeter, but is also a digital 1 Kv insulation tester. Regardless of the added funcionality it is larger than the average DMM.
Needless to say, this is a rather expensive unit built with professional users in mind. It should offer plento of versatility for both maintanance and troubleshooting tasks. This being a DMM from Fluke, the 1587 is a reliable professional tool; durable yet as simple to use as you’d expect from a high quality device.
This insulation multimeter should be a practical tool when working on generators, switches, motors and cables, as well as most industrial and elecrical jobs. Also included in the package are:
- Test leads
- Alligator clips
- Remote probe
- K-type thermocouple
… and considering the rather steep price it should come as no surprise tha batteries are in fact included (uses regular AA batteries). Manuals, including a digital edition, are also in the box.
The 1587 is delivered in a robust hard case and comes with a 3 year warranty.
The Simpson 260-8 is an analog multimeter with the provisions of measuring Voltage, Ohms and Milli-amperes. The manufacturer has named it a VOM. Each of the functions has a different scale and there is a mirror on the dial. Thus parallax is reduced and a better accuracy of the measurement is ensured.
Functions on the VOM
In fact, this instrument has the three major functions of voltage, current and resistance. DC voltage is measurable in nine ranges of 250mV, 1, 2.5, 10, 25, 50, 250, 500 and 1000V. AC voltage may be measured in 2.5, 10, 25, 50, 250, 500 and 1000V ranges. Accuracy varies between 2 and 3%. You can measure DC ampere in six ranges with the meter. The ranges available are 50µA, 1, 10, 100, 500mA and 10A. Well, there is no provision for AC ampere here.
Resistance measurement with the meter is possible in three ranges. The ranges are R X 1, R X 100 and R X 10K. Most interesting thing is, you can measure audible signal on the instrument in decibels.
Well designed different scales are there on the dial of the instrument that helps read any measurement accurately. Parallax is minimized by the mirror on the dial. There are two knobs to select function and range. Another knob to adjust zero on resistance measurement is also there on the meter.
- Operation is simple
- Tri colored marking of dial makes it easy to read
- Jacks are safe as reverse is recessed
- Strong outer casing for longer lasting
- Portable and workable both in field and work shop
- Test leads are long and probes are threaded for extension
In the digitally flourishing present time, an analog instrument is surprising. Still, its simplicity and ruggedness may be interesting to some users.
Ex 320 DMM is a miniature multimeter
The Ex 320 DMM is a miniature multimeter with eight of the most essential functions and non-contact voltage detector. It’s so small that you can hide it in your palm. At the same time it would serve your purposes of fault detection in electrical circuitry.
- Automatic range selection
- Basic accuracy is 0.5%
- Built in non-contact voltage sensor (NCV) with beeper and LED indicator
- Large LCD display at a high contrast
- Maximum hold and data hold action
- Auto Power off
Non-contact voltage detection is a good safety feature. Before going to work on a system you are made aware of the presence of voltage. Maximum hold enables you to see the maximum value of a pulsating data. You can hold any data to watch later.
Voltage measurement on the DMM starts at 0.1mV and terminates at 600V. This is true for both AC and DC volts. 0.1 µA is the lowest ampere range to be measured on this meter and the highest ampere range covered is 10 A. Resistance measuring range of this instrument is 0.1Ω to 20 MΩ. Diode and continuity test is there on the meter.
The DMM weighs only 260 grams. So you can easily carry it anywhere you like. The holster of the meter is strong enough to protect it. It has a tilt stand to place the meter at a convenient angle. The Multimeter is supplied with test leads and two AAA batteries.
Fluke 77-4 Automotive
The Fluke 77-4 (or 77-IV) is simply a yet-again-improved model in the Fluke 70 series instruments. Fluke 77-4 manages most industrial needs of electrical and electronic testing. The term ‘automotive’ in its title is really quite superfluous information, since this is just one of the many potential uses for this meter. Like any other Fluke item it’s well built and looks nice. At the same time you can hold it comfortably. The screen is big and brightly lit for easy monitoring in low light corners.
Fluke 77-4 measures and tests all common variables in electrical and electronic concern. Voltage measurement is wide enough, from 1 mV to 1000 V for DC and AC. Current range is 10 A in both cases. Resistance and capacitance ranges are similarly broad enough to serve most of the purposes of a professional electrician. One must agree that 50 MΩ and 9999 µF are sufficient for most of the measurements.
Well, milliampere measurement for AC and DC is also present in the meter. A beeper is incorporated to indicate continuity and diode test result.
The following features differentiate this instrument from equivalent meters of other brands.
- Big display with backlit
- Records Min and Max
- Auto and manual range selection
- Safety Classes of CAT III and CAT IV are met
- Ergonomic outer casing
- Hands are free with a magnetic hanger (optional)
- Indicates over range and wrong lead connection, better safety
This DMM is sold as an automotive instrument, but it is also a general purpose multimeter for field and shop use. It meets almost all requirements of a professional user. At the same time it’s quite safe for the amateur who requires a top-quality device.
Fluke 233 Remote Display
The Fluke 233 is a digital multimeter from the professionals’ favored brand with all necessary functions present. The special feature is a removable display that you take off the meter and then works through a wireless link. Sometimes it may be a lot safer and/or more convenient to work in this mode.
AC/DC voltage and current ranges are 1000 V and 10 A and accuracies vary from 0.25% to 1.50%. Resistance measurement ranges from 0.1 Ω to 40.0 MΩ. You can measure a capacitor as low as 1.0nF and a maximum of 9999 µF with this instrument. Frequency and temperature (400°C) measurement opportunity is there on it. 5 Hz to 50 kHz frequencies are within reach of this meter.
- True RMS of AC parameters
- Built in thermometer
- Display is workable from a distance of 10 m
- The magnetic display can be fixed on any convenient position
- Auto power off saves battery
- Records Min/Max and average values
- Diode and continuity test is possible
- Large, bright screen
- 3 years warranty
The unique wireless, separable display allows you to connect the meter cautiously and watch the display from a safe distance. Thus you remain completely safe even in a risky situation. It’s rather like doing the work of two people alone. As you fix the display unit on the DMM it transforms in to a good conventional multimeter. Like all products from Fluke, the quality is second to none, and for those that have need of this extra safety measure, the 233 is clearly an interesting product.
Fieldpiece SC53 (Clamp, Dual Display)
In a single meter you’ll have two readings of ampere and volts on the SC53. One display is dedicated to ampere and the other you can choose yourself. Non-contact voltage measurement is of course a vital advantage of this DMM. While you are measuring a current with this instrument, you can simultaneously measure another parameter like capacitance, resistance, voltage or temperature. So you get the work done faster.
In addition to voltage, current and resistance, the SC53 measures capacitance and temperature. Voltage ranges available here are 4, 40, 400 and 600 volts. This is true for both AC and DC systems. The accuracy level for DC voltage is ±.5%. This is a bit worse for AC.
Ampere ranges measurable with the meter are 40 and 400A and accuracy is ±2.0%. Capacitor measuring ranges are 4, 40, 400µF, 4mF and correctness is varied by ±3.0%. The SC53 measures temperature up to a maximum value of 400°F and its accurate by ±1.0%.
You can test continuity of a circuit as well with this meter. A beeper is there to indicate a maximum of 25Ω path resistance.
The DMM SC53 has quite a lot of advantages over competitors’ equivalent clamp meters, including the most obvious:
- Dual display
- Non-contact voltage (NCV) function
- Direct AC ampere (400A) measurement
- Temperature measurement
- Typical jaw to operate with one hand
- Data hold function
The package with Fieldpiece SC53 contains the clamp meter, vinyl test leads, 3 lithium-ion batteries, operating manual and a carrying case ANC4. So you can start working immediate after you receive the consignment. An NCV function alerts you before you go in contact with a live circuit. Above all, this Clamp meter is designed with better safety features for field use and it should be highly convenient to use in the field. Even a novice should be able to use it safely.clamp
Extech MN36 Mini Multimeter
The MN36 is an auto ranging mini multimeter. Small or not, it has all basic functions of a professional multimeter. It is so small that you can comfortably keep it in the pocket of your trousers. It’s well shaped to hold and operate easily.
Extech’s MN36 measures AC/DC voltages and AC/DC amperes. The highest voltage range on this instrument is 600V for both AC and DC. Lowest range for DC is 400 mV and for AC it’s 4V. Maximum ampere range is 10 A and minimum is 400 µA in both the cases.
Resistance measuring ranges start from 400Ω and finish at 40 MΩ. Capacitance, frequency and temperature measuring ranges of the meter are also very much convenient for an electrician’s use. K-type thermocouple is included in supply with the instrument that measures temperature as high as 1400°F (750°C).
Features worth mentioning
The instrument comes with a good number of features worth pointing out, such as the following:
- Large and bright digital display
- Very small in dimension and weight
- Well protected in rubber holster
- Auto range selection
- Data hold option is present
- Power source is simple two AAA batteries
- Continuity and diode test is possible
The DMM is supplied with test leads and two AAA batteries for operation. Yes, the temperature probe is also included. So you get a handy, mini multimeter at a very competitive price. At the same time it will serve you well in solving electrical and electronic system problems.
Klein MM2000 HVAC True RMS
The Klein MM2000 is another good digital instrument from Klein Tools and a more advanced version of the MM1000 from the same manufacturer. It competes with other high-end meters like the Fluke 179. It’s a true RMS multimeter with an extensive feature set. Its shape and color combination is a bit different compared to competing meters. Brilliant black at the center and orange ends present an attractive look, if such things were important. Due to flattened ends it is comfortable to hold in your hand.
It has all the common functions of an electrician’s multimeter. Voltage, current and resistance are obviously present on it. In addition, it measures capacitance, frequency/duty cycle and temperature. The ranges of the parameters are convenient for most industrial purposes.
The meter’s voltage range is 1000 and current range is 10A on this instrument. 40MΩ is the highest range of resistance measurement. Well, you can measure µA even as low as 0.1 with this multimeter. Maximum range of capacitor measurement on this meter is 4000µF.
The temperature measuring range of the instrument is wide enough, from -58 to 1832°F.
- True RMS value
- Bright backlit display
- Graphic display (bar graph)
- Low impedance measurement
What you get
When you purchase an MM2000 HVAC true RMS DMM you get the following:
- The DMM
- Thermocouple for temperature measurement
- One set of batteries
An MM2000 can probably serve you just as well as similar and more expensive instruments from competitor brands.
Klein Tools MM1000
The Klein MM1000 is a digital multimeter with an auto ranging feature; it provides most of the essential functions an electrician has to encounter. It seems to be well built in size and shape. The ribs on the two sides of the meter facilitate a stronger grip.
This DMM measures AC/DC voltage and current, resistance, capacitance, frequency and duty cycle. The instrument also operates on micro amperes and temperature. The range for voltage is 1000 and ampere is 10. The highest resistance it can handle is 40MΩ and lowest micro ampere it can measure is 0.1µA. Highest capacitance range of this meter is 4000µF. Yes, you can test diodes and continuity also with this tool.
The multimeter possesses the following salient features:
- Auto ranging in measuring voltages
- Backlit, brighter display
- Bargraph can measure fast changing parameters
- Flame detectors can be checked with µA range
- Rubber mold casing makes it drop proof
- Better safety with CAT IV
Buying an MM1000 also gets you the thermocouple for temperature measurement. Test leads and the battery required for the instrument are also supplied along with the meter. So you get a ready-to-use instrument for testing and diagnosis of electrical problems.
Extech EX505-K Industrial MultiMeter
Ex 505-K is a digital multimeter kit designed for industrial use. The double molded outer shell of the meter makes it water protected and drop proof. It carries all necessary functions required by an industrial electrician. K-type temperature element is also included in the DMM.
The Ex505 is a true RMS instrument. A high contrast backlit display enables you to read a measurement anywhere in an industrial environment. Voltage range for both AC and DC is 1000 and current ranges are 10 A in either case.
The meter measures resistance up to 40 MΩ and capacitance range is 200µF. Measuring range of frequency is 10 MHz. Temperature as high as 1382°F is possible to measure with the DMM. You can test continuity and diode on this instrument. Basic accuracy is 0.5%.
The instrument kit contains the following:
- CAT IV 600V safety grade heavy duty multimeter
- DV 25 model dual range AC voltage detector
- TL 808 CAT III 1000 V test lead kit ( 8 pieces)
- Heavy duty test leads
- Type K thermocouple and connection adaptor
- Magnetic hanger for hands free operation
- Soft case to accommodate all the items
So you basically have all the accessories for electrical and electronic testing and measurement in a well organized manner in the nice, soft case.
The rugged design and IP 67 class of the DMM makes it water proof and drop proof (2 meters). This True RMS multimeter is very suitable for industrial use. Relative mode is present and data hold and auto power off features of the meter are of course also advantageous. The handy size and light weight (360g) of the meter makes it super value for the money.