Is the multimeter measuring voltage in AC mode connected in series or parallel?
The multimeter measures voltage in parallel and current in series, whether it is AC or DC. The internal resistance of the multimeter in the voltage range is close to infinity, so if the voltage range is selected and the multimeter is connected in series in the circuit, there is actually no current or the current is very small, so no data can be measured. For the current range, the internal resistance is close to 0, so connecting it in series in the circuit does not affect the operation of subsequent electrical appliances.
But if the wrong current mode is selected and connected in parallel in the circuit, such as the situation asked by the main question, if the voltage mode is changed to the current mode and connected in parallel at both ends of the 220V power supply, it is quite dangerous. It will directly short-circuit and may burn out the multimeter or circuit.
The voltage range is relatively safe to measure, and even when connected in series in a circuit, it will not cause as much harm as if the current range is connected incorrectly. We use a multimeter to measure some data, so we must think about how to measure it before measuring.
Whether it is in series or parallel, the first thing to understand is the principle of measuring AC voltage with a multimeter. The multimeter head can only measure DC voltage, which means it can only measure DC voltage. So why can it measure AC voltage? It is because the multimeter has a rectifier circuit inside, which uses the unidirectional conductivity of the diode to convert the AC signal into a DC signal. Therefore, it can measure AC voltage. That is to say, when measuring the 220V voltage in the AC range of a multimeter, it is a parallel circuit.
Principle of AC voltage measurement: When measuring AC voltage with a multimeter, there is a half wave rectification circuit inside the multimeter. When measuring AC voltage, the AC voltage is rectified into DC voltage and then passed through two meters. Finally, the AC voltage is measured based on the size of the DC current. Moreover, the AC voltage displayed on the multimeter is not the instantaneous value of AC current, but the average value over a period of time, that is, the effective value. In fact, the inside of a multimeter is not that simple. It also needs to go through an operational amplifier to amplify the signal, sample it, perform analog-to-digital conversion, and finally display the result on the screen.
When measuring the 220V voltage of a household, simply select the AC range and use a Fluke digital multimeter to explain. Insert the black and red probes into the corresponding positions and directly connect them across the mains neutral wire. There is no need to distinguish which wire is the live wire and which wire is the neutral wire, and the voltage can be read directly
