Is the voltage measured by the AC range of a multimeter in series or parallel
A 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. Therefore, 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 current level is mistakenly connected in parallel in the circuit, for example, in the situation asked by the questioner, if the voltage level is changed to the current level and connected in parallel at both ends of the 220V power supply, it is quite dangerous. If it is directly short circuited, it may burn out the multimeter or circuit.
The voltage range is also relatively safe to measure, and even if connected in series in a circuit, it will not cause as much harm as the current range being connected incorrectly. We use a multimeter to measure some data, so before measuring, we must think about how to measure it.
Whether it is 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 AC voltage be measured again? It is because the multimeter has a rectifier circuit inside, which uses the unidirectional conductivity of the diode to convert AC signal into DC signal, so it can measure AC voltage. In other words, the AC range of a multimeter can measure household 220V voltage, which is a parallel circuit.
Principle of AC voltage measurement: When measuring AC voltage with a multimeter, because there is a half wave rectification circuit inside the multimeter, when measuring AC voltage, the AC voltage is rectified to DC voltage and then passed through two meters. Finally, the AC voltage is measured based on the magnitude of DC voltage. Moreover, the AC voltage displayed on the multimeter is not the instantaneous value of AC power, but the average value over a period of time, which is the effective value. In fact, the internal components of a multimeter are not only simple, but also require an operational amplifier to amplify the signal, sample it, and perform analog-to-digital conversion, and the final result is displayed on the screen.
When measuring the 220V voltage in a household, simply select the AC range and use the Fluke digital multimeter as an example. Insert the black and red probes into the corresponding positions and directly connect them to the mains zero wire. There is no need to distinguish which one is a live wire and which one is a zero wire, and the voltage can be read directly
