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A multimeter is a type of electronic instrument that electronic technicians and engineers frequently use. It’s also known as a VOM (volt-ohm-milliampere) and is a multi-measurement electronic measuring device.
They’re used by electricians to troubleshoot electrical problems in motors, power supplies, appliances, circuits, and wiring systems. DIYers can also learn how to use multimeters to take basic measurements around the house.
It is used to measure voltage, current, and resistance, which are the three basic electrical characteristics. It can also be used to determine whether two points in a circuit are electrically connected. They can be used for everything from simple testing like battery voltage measurement to fault detection and complex diagnostics, and they come in both analog and digital configurations.
Types of Multimeter
- Analog Multimeter: A moving coil meter and a pointer that indicates the scale reading make up the analog multimeter, also known as a VOM (Volt-Ohm-Milliammeter). A coil wound around a drum and placed between two permanent magnets makes up a moving coil meter. It has the advantages of being inexpensive, not requiring a battery, and being able to measure fluctuations in readings.
- Digital Multimeter: The Digital Multimeter’s internal circuitry includes signal conditioning and an analog to digital converter, as well as an LCD and a knob for selecting different variations of the three electrical characteristics. Its benefits include a direct display of the measured value, high accuracy, and the ability to read both positive and negative values.
- Fluke Multimeter: The Fluke digital multimeter can be customized to include a variety of collaboration features. It usually has a large display and is used to measure voltage and electrical resistance. It is primarily used to calibrate currents, volts, and other electrical units.
- Clamp Multimeter: Electricity flow is measured using a clamp digital multimeter. When the probes measure volts, this multimeter’s clamp feature measures amps. While measuring, the appropriate feature is used.
- Autoranging Multimeter: The auto-ranging multimeter is the easiest to use of all the digital multimeters, but it is also the most expensive. It has fewer positions and a knob in the center. This instrument can be used for simple projects, and it is highly recommended for beginners as well as home electricians.
Benefits of Multimeter
- The electrical output can be used to send and receive data with other devices.
- There is no effect from loading due to the high input impedance.
- A clear reading can be obtained at greater viewing distances.
- The display of the output can be done automatically.
- It can auto-polarize.
- These are less expensive because of the integrated technology.
Limitations of Multimeter
- The LCD is primarily powered by an external source, such as a battery because the LCD becomes dim and difficult to read when the battery is depleted.
- The meter must be used following the manufacturer’s specifications and the category rating; otherwise, the meter will be damaged, resulting in the loss of equipment.
- The multimeter’s limit is 1V, so if it’s exceeded, it’ll be damaged.
- Power supply and isolation requirements
- Testing for continuity and resistance
- Determining the frequency
- Testing the switch
- A faulty power cable can be identified.
- Testing the batteries
- An outlet can be tested.
- It’s used for environmental and temperature control.
- Diode testing
- AC/DC measurement
- Voltage measurement (AC/DC)
- Old incandescent light bulbs can be tested.
- Measurement of time and frequency
How to Test an Earth Rod with a Multimeter?
Switch the multimeter dial selector to AC voltage measurement. Multimeters can measure voltage, current, and resistance, among other things. In an analog meter, set the dial to the letter “V” with wavy lines for AC power. Turn the dial selector on a digital multimeter until AC voltage is reached. To get an accurate reading, set the voltage on the meter to the highest value.
Insert the red and black probes into the multimeter’s respective ports. To test your outlet, connect the red probe to the port labeled “V,” “,” or “+,” and plug the black lead into the port labeled “COM” or “-.”
Begin taking a reading while the probes are in an outlet’s live and neutral ports. Place the red probe’s tip in the outlet’s neutral port, which is the smaller slot in the outlet socket. Then insert the black probe’s other end into the alive port, which is the larger slot in the outlet. Now, on the multimeter, check the voltage reading and save it. This is your first reading.
When you’ve inserted the multimeter leads into the live and earthing ports, start checking the voltage. Now carefully remove the red lead from the neutral port and place it in the earthing port, which is usually a circular hole on the top or bottom of the outlet. To see the voltage measurements, begin by checking the reading on the multimeter. This is your second reading, so save the previous ones to compare.
Calculate the total leakage on your outlet and see if it’s under 2 volts. Leakage is defined as the total number of volts transferred from your earthing port to the outlet. Subtract the first reading from the second reading from the (live to neutral) ports (live to earthing).
After that, subtract the number of volts from your third reading (neutral to earthing). If the number is greater than 2 V, your earthing is defective. Aside from that, the outlet is perfectly safe to use.
As an example,
Assume your initial reading was 230 V.
231 V was the second reading.
0.5 V was the third reading.
(231-230) + 0.5 = 1.5 V is the formula.
Since it is less than 2.0 V, this indicates that the earthing is perfect.
Tips for testing earth rods
- If you already have home earthing, your reading will be the same, or with a difference of only 5 volts, when compared to the previous reading.
- Furthermore, the reading between the live and earthing ports should be zero or close to it. This indicates that your house outlet does not have any earthing.
- If your outlet lacks an earthing port, it is not connected and therefore does not need to be earthed.
How to Test an Earth Rod with a Multimeter?
The earth rod is a safeguard for human safety that provides consistent and long-term protection. Simply follow the instructions above to test an earth rod with a multimeter.
- Is it true that earthing keeps you safe from EMFs?
Low-frequency electric and magnetic fields of 100,000 Hertz or less are effectively diverted by earthing.
Electromagnetic fields from A/C electrical wiring and most household appliances can be shielded by it. Unfortunately, no research has been conducted on earthing and mobile phones, or other higher frequency electromagnetic fields such as Wi-Fi and smart meters.
- Is the grounding slot on a power outlet active?
Yes, just like the “hot” slot in an electrical outlet, the grounded slot is “live” in the sense that it is designed to conduct the power used by devices plugged into it. It’s also grounded at the service panel, just like the grounding slot in a three-slot receptacle, if done correctly.