Use of digital multimeter_Digital multimeter tutorial
This is the most commonly used function of the electric pen, that is, hold the electric pen in the correct posture and touch the conductor with the pen tip. If the electric pen lights up, it proves that there is voltage in the circuit, and if the light does not light up, it proves that there is no voltage in the circuit.
But in actual use, you need to pay attention, you can't judge whether the circuit is normal or not only by the light of the electric pen. For example, both the normal neutral wire and the disconnected neutral wire in the unused state cannot light up the electric pen, but the former is a normal phenomenon, and the latter is a fault. For another example, both the live wire under normal conditions and the wrongly connected neutral wire can light up the electric pen, but the former is a normal phenomenon, while the latter is a malfunction.
Measuring in-phase or out-of-phase of phase wires
Circuits that do not distinguish between wire colors will definitely cause headaches during maintenance. The single-phase circuit is okay, but if you encounter a three-phase circuit, it is really a big headache!
However, the electric pen has a magical function, which can easily help you measure the in-phase or out-of-phase of the phase wires.
When measuring, hold an electric pen in each hand and stand on an insulating object. Touch the two electric pens to the two wires at the same time. If the brightness of the two electric pens is low, it means that the two lines measured at this time are in phase (both are phase lines). If the brightness of the two electric pens is high, it means that the two lines measured at this time are out of phase (one phase line and one neutral line).
With this method, three phase lines and one neutral line in a three-phase circuit can be quickly screened out.
Distinguish between alternating current and direct current
First of all, it is distinguished from the brightness. The brightness of the electric pen when measuring alternating current is significantly higher than that of direct current.
The second is to distinguish from the position of the brightness of the electric pen. The luminous body of the electric pen is called a neon tube, which is in the shape of a long strip. When measuring alternating current, the entire neon tube glows; when measuring direct current, only one end of the neon tube glows.
Measure the positive and negative poles of direct current
We said in the previous paragraph that only one end of the neon tube lights up when measuring direct current. At this time, the positive and negative poles of the power supply can be judged by the position of the neon tube emitting light.
When measuring the positive pole of the power supply, the end of the neon tube near the tip of the pen lights up; when measuring the negative pole of the power supply, the end of the neon tube away from the tip of the pen lights up.
