What happens if you measure ac voltage with dc multimeter

Home
Measuring equipment
Cross line lasers
360-degree line lasers
Multimeters
Cable locators
Tape measures

Table of Contents Show

1. What's a multimeter?
2. What type of power source are you going to measure?
3. Measure electrical voltage
4. Measure electrical power
5. Measure electric resistance
6. Other functions
Do you have any feedback for us about this page?
Can I measure AC voltage with DC multimeter?
Why can't we use a multimeter to measure AC current?
Why we Cannot use DC voltmeter in an AC circuit?

A multimeter is a device that you can use to measure a number of electrical quantities and functions. That's all well and good, but what exactly do you measure? And what do you need the information for? We'll take you through the basics of electricity and multimeters, so you can get to work with them.

1. What's a multimeter?
Type of power source
Electrical voltage
Electric power
Electrical resistance
Other functions

1. What's a multimeter?

Electricity and electrical circuits are very important in our daily lives. To install, maintain, and repair them, you need equipment to work with them. That's where multimeters come in. Think of them as an electronic tape measure for measurements on electronic circuits. You make these kind of measurements when you want to investigate if there are issues with the electrical cable or if you want to check if you've connected the sensor to the lamp correctly. Or maybe electricity is a hobby for you. There are multimeters with various functions, but they mainly measure voltage, power, and resistance.

2. What type of power source are you going to measure?

Before you start measuring, you need some information. Are you dealing with a direct current (DC) source or an alternating current (AC) source? With direct current, the direction of the voltage is constant, like with an exchangeable battery or battery. An AC power source has a variable direction, like the sockets in your home. Most appliances you have at home have a function which converts AC voltage to DC voltage. That means that if you're going to make measurements in your lamp or television, you're dealing with direct current. Direct current is often indicated by a straight or dotted line above or beside the V. You can recognize alternating current by its wavy line.

3. Measure electrical voltage

If you have a fault in your circuit, you'll usually first use your multimeter to check the voltage. Always connect the black measuring needle to the COM input and the red to the V input, which often says 'Ω' or 'mA' as well. Choose the highest possible range, so you don't overload the multimeter. Touch the circuit with the measuring needles in such a way that you have a device between the measuring needles. In other words, switch the multimeter in parallel with the measuring object. Look at the measured value while carefully considering the unit of measurement. If necessary, adjust it downward until you see the correct value.

4. Measure electrical power

For power measurements, you must connect the multimeter in series with the power circuit. This means that you need to open the circuit and place the meter in between. First, switch off the power supply to the circuit. Then connect the black test needle to the COM input and the red one to the ampere input. Carefully check the measured value which is usually expressed in amperes or milliamp) and the measurement function (direct or alternating current). Once you have closed the circuit again, turn on the power supply. Sometimes , you don't have the option to open the circuit. In that case, you can include the conductor with an ammeter or power clamp. and don't need to open the circuit.

5. Measure electric resistance

You can measure the resistance when the circuit is de-energized. The first thing you need to do is turn off the power supply. Then you can set the multimeter to resistance measurement (Ω). Connect the black measuring needle to the COM input and the red one to the Ω input. Now touch the tips of the resistance to be measured with the tips of the measuring needles, for example in a lamp. View the measurement result and make sure that you've selected the correct unit of measurement (ohm, kilo ohm, or mega ohm).

6. Other functions

Maybe you want to measure other things besides voltage, power, and resistance. There are several more functions available on a multimeter, such as finding out the charge state of batteries or checking if your measuring circuit is closed. Or maybe you want to measure the temperature of an object. Since none of these are standard functions of a multimeter, you can choose the best multimeter for you by using our selection tool with these functions.

Do you have any feedback for us about this page?

Optional

We only use your feedback to improve the website, we won't respond.

Article by:

James Multimeter Expert.

Can I measure AC voltage with DC multimeter?

With a digital meter that auto-senses polarity, you will get a negative accurate reading if you have a DC setting and measure DC with the polarity reversed. It will show zero or an error if the polarity is reversed and it isn't auto-sensing. AC will display as zero voltage on a DC setting, regardless of the polarity.

Why can't we use a multimeter to measure AC current?

As an analogue multimeter does not contain any active electronics, the diode rectifier used to rectify the alternating waveform has a certain turn on voltage and this will affect the low voltage end of some scales. Some meters may not be able to measure AC current, or they will have very restricted ranges.

Why we Cannot use DC voltmeter in an AC circuit?

DC measurement instruments measure the average value. In AC current, the average value is zero as the current oscillates. Therefore DC instruments can not measure the Ac current.