The principle of electropen detection for luminescence is that there is a certain potential difference between the charged object and the earth. When the potential difference exceeds a certain value, the neon bubble will emit light, and if it falls below a certain value, it will not emit light. The voltage measurement range of an ordinary low-voltage test pen is generally between 60-500V, and neon bubbles below 60V may not emit light. When the voltage is higher than 500V, it is not possible to use a low-voltage test pen for testing, otherwise insulation breakdown may occur, causing a risk of electric shock to the human body.

Because the zero wire is short circuited but the live wire is connected, a circuit is formed between the charged body, test pen, human body, and the earth during the electricity measurement, so the neon bubbles in the test pen will emit light. When measuring the live wire, there is a voltage of around U=220V between the live wire and the ground, and the human body resistance is generally very small.

Usually only a few hundred to several thousand ohms, while the resistance inside the measuring pen is usually around a few megaohms. The current through the measuring pen is very small, usually less than 1 milliampere. When such a small current passes through the human body, it is not harmful to people. When such a small current passes through the neon bubble of the measuring pen, the neon bubble will emit light.

Function 1: Electricity testing, using a metal head to touch an object. If it emits light, the object will be charged, and if it does not emit light, it will not be charged.

Function 2: It can be used for low-voltage nuclear phase measurement to determine whether any wires in the circuit are in phase or out of phase.

Function 3: It can be used to distinguish between alternating current and direct current. When using a test pen for testing, if both poles in the neon bubble of the test pen emit light, it is an alternating current; If only one of the two poles emits light, it is direct current.

Function 4: It can determine the positive and negative poles of direct current. Connect the test pen to a DC circuit for testing, and the electrode with the neon bubble shining is the negative electrode, while the electrode without the neon bubble shining is the positive electrode.

Function 5: It can be used to determine whether the DC is grounded. In a DC system with insulation to ground, standing on the ground can be used to contact the positive or negative poles of the DC system with a measuring pen. If the neon bubble of the measuring pen is not lit, there is no grounding phenomenon. If the neon bubble lights up, it indicates grounding. If it lights up at the tip of the pen, it indicates positive grounding. If it shines on the finger end, it is negative grounding.