How to judge the three wires of fire, zero and ground by digital multimeter
How to judge the three wires of fire, zero and ground by digital multimeter
Insert the black test lead of the digital multimeter into the "COM" hole, the red test lead into the "V/Ω" hole, switch the gear to the maximum range of AC voltage, hold the tip of the black test lead with the left hand, and touch the tested circuit with the tip of the red test lead with the right hand (do not Touch the tip of the pen), at this time the multimeter will display a certain voltage value, the judgment method is as follows:
The line with the highest displayed voltage value is the live wire, and the specific value is uncertain, generally tens to hundreds of volts. After the live wire is found, the remaining two wires are the neutral wire and the ground wire. Because there is a potential difference between the zero wire and the ground wire, there will be a small numerical display when measuring the neutral wire, and the displayed value is always when measuring the ground wire. Zero, so that you can judge the zero line and the ground line.
To sum up, according to the above method, we can easily identify the live wire and the neutral wire. Now there are still digital multimeters with the live wire identification function, that is, the HV live wire gear. The operation method is the same as above, and the one that displays HV is the live wire. , does not display HV's ie neutral or ground.
May I ask how to check the ignition coil on the car with a multimeter?
1. The multimeter can only measure its on-off and resistance values for reference. However, most ignition coil faults are inter-turn short circuits (high-voltage breakdown), which cannot be measured with a multimeter. You can also use battery power to instantly connect the input terminal (primary), and the output terminal will have a high-voltage output (secondary).
2. The multimeter can measure the resistance of the two high-voltage terminals, but it cannot judge the failure of the ignition coil.
3. The voltage value between the terminals of the independent ignition coil plug is different due to the different coils, so it cannot be judged whether the ignition coil is good or bad.
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1. Any coil has a secondary coil and a primary coil. The coils used on the distributor are all output by a high-voltage head, and then distributed to each cylinder.
