Which multimeter is good for professional electricians?
Pointer multimeter measurement error, conversion rate is slow, but the measurement of capacitor charging and discharging display intuitive, AC voltage block using half-wave rectification (diode rectification) so the pointer multimeter AC voltage block measurement error is large because of the AC voltage block using half-wave rectification, so that the pointer multimeter AC voltage block measurement is the average value of the alternating current, because the measured AC signal is after the divider resistor divider after half-wave rectification out is DC current, reflecting the average value of alternating current, pointer multimeter input impedance is not as high as digital multimeter input impedance, sensitivity is not as high as digital multimeter sensitivity. Rectified out of DC current, reflecting the average value of AC power, pointer multimeter input impedance is not as high as the input impedance of the digital multimeter, sensitivity is not as high as the sensitivity of the digital multimeter, but the professional electrician or recommended MF-47 pointer multimeter, the new MF-47 circuit design, the resistance block and the current block were retrofitted with varistors to do the over-voltage protection elements, some MF-47, MF-47 It is not suitable to measure AC power for a long time, and it is easy to burn the voltage divider of the lowest AC voltage block and the rectifier diode in the rectifier, which causes large measurement error of AC voltage block or the failure of all AC voltage blocks. (Burning the voltage divider of the lowest AC voltage block, i.e., 38.3K resistor connected to the AC 10V block, will lead to the failure of all AC voltage blocks. Failure, and generally burned AC voltage block in the rectifier of the two rectifier diodes in one of the AC voltage block will appear in the AC voltage block measurement error or AC voltage block failure) or that is to say, the gear switch contact is poor, or the gear switch short-circuit caused by the burning of the voltage divider resistor or burning rectifier diode caused by the failure of the AC voltage block, because now the gear switch is a PCB switch.
Multimeter maintenance of some experience, you can measure the AC power, but it is not suitable for a long time. Mainly to determine whether the 220V or 380V voltage is normal, but if frequent or prolonged measurement of alternating current, then the MF-47 AC voltage block voltage divider resistor as well as rectifier diode will have impact, I have written in the above MF-47 pointer multimeter AC voltage block faults are prone to.
