What comes to your mind when you here the word multimeter?I guess a lot of things are triggered in your head.For me when I hear this word multimeter, I relate it to many, which is many meters.
What is a multimeter?
A multimeter is an electrical measuring instrument or device that can measure several electrical and electronics functions in one unit. A typical multimeter can measure voltage, current, and resistance. Nowadays, multimeters can measure frequency, capacitance and many other electrical and electronics parameters.
Types of multimeters
Basically there are two types of multimeters. A multimeter can either be digital or analogue.The aim of this post is not to go into the details of how a multimeter operates. Therefore, I will limit the discussion to using the multimeter. To enable you to obtain correct measurements, that will help you to make the right diagnosis.
Things to consider when using a multimeter.
In order for you to use a multimeter safely. You should know the three basic parts of a multimeter that will help you to measure a desired electrical quantity. Below is a list of the three basic parts of a multimeter that will help you to use a multimeter.
- The display.
- Selector Knob/Dial.
This is where the value of a measured quantity is displayed or shown. It can be current in amperes ,voltage in volts , resistance in ohms or frequency in Hertz.
The sole function of the selector knob, is to allow you the user of a multimeter. To navigate through the different functions or meters of the instrument. For example, if you want to measure voltage. You use the selector knob to select the voltmeter on the multimeter.
The probs are the two leads cables that help you to measure the selected component. It can be voltage, current and any desired electrical function you would want to measure. Probs are a connecting link between the multimeter and the device you want to measure.
Safety tips to follow when using a multimeter.
Safety is everyone’s responsibility but ultimately it is in your hands. Therefore,here are the safety tips you should follow when using a multimeter.
- Work on de-energized circuits whenever possible.
- On live circuits, use protective gear.
- Use insulated tools.
- Wear safety glasses or use a face shield.
- Wear insulated glove,remove jewelry and watches.
- Stand on an insulated mart.
- Wear flame-resistant clothing.
- When making measurements on live circuits. Use the three-point test method especially when checking to see if a circuit is dead. First test a known live circuit.
- Second test the target circuit.Third test the live circuit again this verifies that your meter worked properly before and after the measurement.
- When you are measuring current, connect the multimeter in series with the component or device you are measuring.
- When you are measuring voltage, connect the multimeter in parallel with the component or device you are measuring.
- Make sure you switch off power to a circuit when you are measuring resistance.
BELOW IS VIDEO ON SAFETY WITH MULTIMETERS BY FLUKE
Basic terms to understand when using a multimeter
2.FREQUENCY: Is the rate of change of direction of alternating current (AC) in a second.
3.CAPACITANCE: This is the ability of a capacitor to hold electric charge. The unit of capacitance is the farad.
4.RESISTANCE: This is the opposition to the flow of electric current in a circuit.
5.VOLTAGE:Is the potential difference between two points in a circuit and it is measured in volts. Voltage is responsible for circulating electric current through the circuit. Or I can say it is the pressure that pushes current or forces current to move through an electric circuit.
6.CURRENT: Is the rate of movement of charge in an electric circuit and it is measured in Amperes.
7.LOAD: In an electric circuit, a load is any component or device that draws current in that circuit. In practice, a load can be a television set, electric cooker, air conditioner, electric bulb. And any appliance that is connected in a circuit.
8.POWER SOURCE: You will agree with me that nowadays, you have a lot of alternative sources of power. This is simply a source where an appliance or device can draw its current or voltage. For its smooth operation. The common sources of power are Electric grid, solar, Stand by generators and batteries. Below is a video of how to use a multimeter by RAW.
How to measure continuity
Mostly, a continuity test is done to find out, if your conductor, circuit breaker, or any other device. Like a cooker, element has a broken path. That is, it can not allow an electric current to pass through it.
When the device that you are measuring is okay. And it has a resistance of fewer than 30 ohms, a buzzer will sound. And when it is okay and it has a higher value of resistance. A certain value of resistance will be shown on the display screen of the multimeter.
Should the device be faulty, on the display screen, OL will be displayed or 1.This is dependent on the brand of the multimeter that you are using to carry out your continuity test.
How to measure current.
Why do you want to measure current? There could be a lot of reasons for doing this. Here are a few reasons why you might want to carry out a current test.
- You can do it just for fun, you want to know how much current a device is taking from the supply.
- You want to verify that the current that is supplied to a particular device is correct. That is, the current is not more or less than the specified amount of current needed for the smooth operation of a device or Equipment.
Therefore, here is how you do your current test or measurement.using a multimeter.
The first thing that you should do is to cut off the current to the device that you want to measure current from. Then connect the multimeter in series with the device or equipment that you want to measure current from. This is done by putting your test leads or probs on the port marked 10A,20A or mA. The other lead is placed on the port marked com. Then you switch on the power. Observe or take the reading that is shown on the display screen of your multimeter.
There times when the current you want to measure is in the high range. What do you do? At this point that’s when you ask for a clamp meter, it is good and very efficient. A clamp meter enables you to measure high current ranges with easy.
How to measure voltage.
Before you measure the voltage.You need to determine the voltage that you want to measure. This can either be AC or DC voltage.AC is alternating current and DC is direct current. Direct current does not change its direction with time.
When you have decided on the voltage that you want to measure. You move the selector knob to either DC voltage setting or AC voltage setting.
Here are the steps you should take when measuring voltage.
- You need to power off the circuit. You do this in order to reduce the danger of a short circuit, especially when you are working on a three-phase system.
- Put the black probe lead into the socket labeled com on your multimeter
- Plug the red probe lead into the socket labeled V.In most multimeters, this socket is also marked with omega and diode symbols.
- Make sure your multimeter is connected in parallel with the load that you want to measure voltage.
- Touch the black probe against the first point you want to measure.
- Then you power the equipment.
- Touch the red probe against the second point that you want to measure.
- Then take the reading on the LCD display of your multimeter.
How to measure resistance
When you are measuring resistance . The prob, measuring lead is plugged into the multimeter the same way you plug it when you are measuring voltage.
Here are a few things you must consider when measuring resistance. You should always do resistance measurements on a dead circuit. That is, power off the equipment. If the component that you want to measure the resistance on is in a circuit. Remove it completely from the circuit or remove one leg from the circuit. This is done to prevent other components. That is connected in parallel with the component you are measuring, does not interfere with the readings.
You take one prob and touch one end of the resistor.Then touch the other end with the second prob.
Check the reading displayed on the LCD of your multimeter. If OL or 1 is displayed, then you need to extend the range. It is important to note that when doing a resistance test, always start with the lowest range. Then you increase until you find the ideal range.
Parallel and series circuits
It is important to state that in order for you to appreciate measuring instruments. You should know and understand the basic characteristics of a parallel and series circuit.
In a parallel connection, the voltage is the same across all devices connected in that circuit. Each device that is connected in a parallel circuit, draws a different current from the supply.That is the current divides.
In a series connection, the current that passes through all the connected devices is the same.While appliance or gadget draws its own voltage. The voltage divides in a series connection.
Fluke 1587/1400 FC 2-in-1 .Insulation Multimeter W /Clamp.
The fluke 1587/1400 2-in-1 insulation tester combines clamp and insulation resistance tester.
- PI/DAR measurements with trident graphs.
- Temperature compensation through fluke connect App.
- Fluke 1400 AC current clamp.
Let me show you how the above-projected features help you to do your insulation and current test.
PI. This is the polarisation index test. This is the ratio of the insulation resistance in megaohms after 10 minutes. Divided by the megaohm after 1 minute.
DAR: Dielectric absorption ratio, is a diagnostic test similar to polarisation index but takes the insulation resistance test usually measured at 30 seconds-1 minute divided by insulation resistance taken 15 seconds-30 seconds after the start of measurements. It is good to know that these tests are conducted in order to ascertain the state of insulation. That is in transformers, motors, and Generators.
The fluke 1587 insulation and clamp testers has fluke app-enabled feature that allows you to take mechanical, and thermal measurements. This feature also allows you save your measured quantity to cloud from your smartphone,tablet, laptop or desktop. As a result, you can share the readings that you have taken with your team in real-time without leaving the field.
The incorporated clamp meter is able to measure current from 1A AC to 400A AC.
Advantages of digital multimeters
- They are more accurate than analogue multimeters
- Digital multimeters, do not have reading and interpolation errors
- Parallax errors are eliminated
- Digital multimeters have auto-ranging feature, this takes the trouble of changing the range whenever you are doing or taking a new measurement.
- Digital multimeter display has no moving parts. This makes them be robust and have a longer lifespan.
Disadvantages of Digital multimeter.
- LCD display,depends on external power supply from the battery.This makes it difficulty to take reading when the battery loses its charge.Because the LCD,becomes Dim.
- They are expensive due to high manufacturing cost
If you have any questions,feel free to ask in the comments sections below.