Is the voltage measured by multimeter in series or parallel?
The multimeter measures the voltage in parallel and the current in series, whether it is AC or DC. The internal resistance of the multimeter is close to infinity, so if the multimeter is connected in series with the voltage range, there is actually no current in the circuit or the current is particularly 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 will not affect the work of the following electrical appliances.
However, if the current gear is selected to be connected in parallel in the circuit, such as in the case of the subject, if the voltage gear is replaced by the current gear and connected in parallel at both ends of the 220V power supply, it will be quite dangerous, and it will be short-circuited directly, which may burn out the multimeter or the line.
The voltage range is relatively safe to measure, and even if it is connected in series in the circuit, it will not be as harmful as the situation that the current range is wrong. We originally want to measure some data with a multimeter, so we must think about how to measure it before measuring.
Whether it is series connection or parallel connection, we must first understand the principle of measuring AC voltage by multimeter. The multimeter meter can only measure DC voltage, that is, it can only measure DC voltage, so why can it measure AC voltage? That is because there is a rectifier circuit inside the multimeter, and the unilateral conductivity of the diode is used to change AC signal into DC signal, so it can measure AC voltage. That is to say, the multimeter AC gear is a parallel circuit to measure household 220V voltage.
Principle of AC voltage measurement: When measuring AC voltage with multimeter, because there is a half-wave rectifier circuit inside the multimeter, when measuring AC voltage, it will be rectified into DC voltage and then passed through two meters, and finally the AC voltage will be measured according to the magnitude of DC, and the AC voltage displayed by the multimeter is not the instantaneous value of AC, but the average value within a period of time, that is, the effective value. In fact, the multimeter is not only that simple, but also the signal is amplified by an operational amplifier, and the final result is displayed on the screen after sampling and analog-to-digital conversion.
When measuring the household voltage of 220V, it is only necessary to select the range of AC gear, which is explained by Fluke digital multimeter below. The black and red probes are inserted in corresponding positions and directly connected to the zero live wire of the commercial power, so it is not necessary to distinguish which is the live wire and which is the zero wire, and the voltage can be read directly.
